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The diet of adult parasitoid wasps is vital for their survival and reproduction. However, the availability of food resources, such as plant nectar, can vary widely in cropping systems, potentially affecting parasitoid fitness and thereby biological control of pests. The egg parasitoid Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) is a potential biological control agent of the pistachio pest Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae). While H. pennsylvanicus is known to attack L. zonatus eggs in California, USA, parasitism rates in orchards are highly variable. Floral resource provisioning has the potential to enhance parasitoid longevity and thus improve parasitism rates, leading to reduced pest densities. Here, a combination of field and laboratory studies was used to assess the influence of flowering groundcovers on the reproductive fitness of H. pennsylvanicus and the abundance of L. zonatus. Evaluated groundcovers included oat (Avena sativa L.), cowpea (Vigna unguiculata L.), white mustard (Sinapis alba L.), and buckwheat (Fagopyrum esculentum Moench). Under laboratory conditions, buckwheat and mustard provided the greatest benefit to female H. pennsylvanicus longevity. However, females provided a buckwheat diet produced the greatest number of offspring over the course of their lifetime. In field trials, flowering groundcovers did not influence the abundance of H. pennsylvanicus nor parasitism rates on L. zonatus. While the availability of floral resources can improve the reproductive fitness of H. pennsylvanicus, the use of groundcovers in pistachio did not enhance biological control of L. zonatus. [ABSTRACT FROM AUTHOR]

The mealybug, Ferrisia gilli Gullan, attacks important crops such as almonds, grapes, and pistachios in California. In pistachios, F. gilli has 3 generations per year, and a single insecticide application timed to the presence of first instars of the first or second generation provided sufficient control. This strategy has, recently, become less effective, and here we tested the possible explanation that F. gilli life stages are smeared, with different life stages present concurrently, reducing the efficacy of a single pesticide application. We monitored F. gilli populations and their natural enemies in central California pistachio orchards from 2021 through 2022. We found the first generation of F. gilli was synchronous, but occurred 3 wk earlier than previously reported. Subsequent generations were smeared. Increased yearly temperatures are a likely explanation for the changes observed in phenology. Almost all natural enemies found were lacewings (n > 10,000). Parasitoids were recovered from pistachios in 2021 (n = 4) and 2022 (n = 164), most were hyperparasitoids. Based on these studies, recommendations are made to monitor F. gilli in early May rather than late May to better target insecticide applications for the first instars. [ABSTRACT FROM AUTHOR]

Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) is a polyphagous insect pest attacking a wide variety of crops. In California's Central Valley, it is now the dominant leaffooted bug on almonds, pistachios, and pomegranates. Leptoglossus zonatus pest status depends largely on overwintering adult survival and reproductive potential, which determines its population size in spring and early summer when nut crops are particularly susceptible to bug damage. Here, we investigated the overwintering reproductive biology of L. zonatus in laboratory and field experiments to gain information about its ovary development, time of mating, and the impact of low temperatures on egg hatch. With dissections of laboratory-reared L. zonatus, we established a baseline for ovarian development and determined that the size of the spermathecal reservoir is larger in mated than in unmated females. Dissections and behavioral experiments of field-collected material provided evidence of mating events before dispersal from overwintering sites. Laboratory trials showed that temperature significantly impacted L. zonatus egg hatch. Leptoglossus zonatus reproductive biology presented provides valuable information on its population dynamics and dispersal from overwintering sites, and will contribute to the development of monitoring and management tools. [ABSTRACT FROM AUTHOR]

California pistachios are threatened by several stink bug species (Hemiptera: Pentatomidae), including the native Thyanta pallidovirens (Stål) and Chlorochroa uhleri (Stål), as well as the invasive Nezara viridula (L.). In pistachio, control tactics often target specific life stages, which makes knowledge about life histories fundamental to successful IPM programs. For that purpose, life history parameters of these stink bug species were assessed. Nymphal development and survivorship at seven constant temperatures, upper and lower development thresholds, thermal constants, adult longevity and fecundity, and life table parameters were evaluated. No species completed development at 15°C or 35°C. For N. viridula, egg to adult development was fastest at 30°C, whereas for T. pallidovirens there was no significant difference between 27.5 and 30°C and C. uhleri development was similar between 25 and 30°C. Egg to adult survival was highest at 22.5°C and 27.5°C. The thermal requirements as degree-days (DD) to complete immature development were estimated to be 714.3, 370.4, and 434.8 for C. uhleri, T. pallidovirens, and N. viridula, respectively. For C. uhleri, life table calculations produced a value of 56.7 d for mean generation time (To), 24.89 for net reproductive rate (Ro) and 0.057 for the intrinsic rate of increase (r). Thyanta pallidovirens had a To of 39.9 d, a Ro of 81.10 and a r of 0.11. The results are discussed with respect to the improvement of IPM in California pistachios, and the information presented may contribute to the control of these pest species in other ecosystems. [ABSTRACT FROM AUTHOR]

The mealybug, Planococcus ficus (Signoret), is a primary vineyard pest in California and other grape-growing regions throughout the World. Mating disruption programs are commercially available to manage Pl. ficus , but widespread adoption has been limited, in part, by high costs compared with insecticide programs. To improve mating disruption economic effectiveness, different deployment technologies (passive, aerosol, and microencapsulated formulations) were individually examined. Adult male Pl. ficus captures in pheromone traps and categorical ratings of vine infestation or crop damage suggest that all deployment strategies lowered mealybug densities or damage. Using passive dispensers, deployment rates of 310 and 465 per ha lowered Pl. ficus crop damage similar to 615 per ha, a rate commonly used in commercial operations; reduced rates would lower product and deployment costs. Meso dispensers, containing more a.i. deployed at 35 per ha did not have a treatment impact, but a microencapsulated formulation and aerosol canisters lowered male flight captures and/or crop damage. Male mealybug flight activity was greatest from 0500–1100 hr, which coincided with temperatures >16° and <32°C. These restricted times and temperatures suggest programable dispensers might allow pheromone deployment to coincide only with flight patterns. A large field trial using passive dispensers found greater treatment separation after 3 yr of pheromone deployment. Discrepancies in results among vineyards may be related to Pl. ficus density, but combined results from all trials suggest that different deployment technologies can be used to impact Pl. ficus densities and damage, even at reduced rates, especially with continued use over multiple seasons. [ABSTRACT FROM AUTHOR]

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a polyphagous insect pest that has invaded much of the United States, including California. Despite model predictions that regions in California like the agriculturally important Central Valley are suitable, H. halys populations and the occurring crop damage are distinctly lower than in regions of the East Coast. To evaluate if this is due to low nymphal survival in the high temperature and intensive monoculture environment, H. halys nymphs were caged on four common Central Valley tree crops: almond, pistachio, peach, and grape, and compared to the well-established almond and pistachio pest Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae). Nymphal development showed that peach, almond, and pistachio can sustain H. halys as single host plants until adult eclosion, whereas grapes cannot. The addition of fruiting structures of almond, pistachio, and grape to H. halys caged on peach trees (= mixed diet) did not increase nymphal survival but did increase adult female size. Leptoglossus zonatus survival was higher than H. halys on pistachio, but not on the other crops. Overall, H. halys nymphal mortality in the field was high, with 92% in the mixed diet compared to 73% in the mixed diet control in the laboratory, indicating abiotic population pressures. Our results confirm peach as a good H. halys host plant and suggest that almond has a similar suitability, and while pistachios can support H. halys nymphal development, they seem less likely to facilitate population growth. [ABSTRACT FROM AUTHOR]

Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch disease, which affects wine grapes and leads to reduced crop yield and quality. While some virus spread can be attributed to the propagation of infected plant material, a greenhouse assay recently demonstrated that the threecornered alfalfa hopper (Membracidae: Spissistilus festinus Say) can transmit GRBV between grapevines. While S. festinus is not considered an economic pest of wine grapes, this species is present in California vineyards and their feeding can cause petiole girdling. Recent surveys have noted a correlation between S. festinus populations and GRBV-positive vines in vineyard areas adjacent to riparian habitat. Here, S. festinus populations were monitored over a 2-yr period at multiple vineyard sites adjacent to riparian habitats. At each site, insects were sampled from ground covers and the vine canopy at the vineyard edge and interior, and vines in both locations were evaluated for petiole girdling. Results indicate that there was no difference in abundance of S. festinus at the vineyard edge and interior. Populations in the vine canopy were highest in the late spring and early summer, and this was followed by the appearance of petiole girdling, indicating a key period of potential GRBV transmission. Furthermore, activity in the vine canopy appears to be amplified when the quality of ground covers is reduced as the season progresses. That said, overall populations of S. festinus were relatively low and additional work is needed to characterize the timing and efficiency of transmission under field conditions. [ABSTRACT FROM AUTHOR]

In 2018, we surveyed cannabis growers about their experiences with California's commercial cultivation legalization system. Our results suggest high rates of noncompliance with the new regulations. Of the respondents, 31% reported income from cannabis and had not applied for cultivation licenses, indicating a violation of state regulations. These findings highlight the need to further explore conditions that might incentivize growers to apply for cultivation licenses. Respondents' answers and comments indicate modifications to cannabis cultivation licensing programs might be needed to reduce compliance costs and regulatory inconsistencies and to overcome threats of legal repercussions from enhanced bureaucratic oversight. Growers characterized legalization as a process that excludes small growers, contributes to an increase in black market sales and undermines the economies in rural communities. More research is necessary, including on the socioeconomic and environmental contributions that unlicensed small cannabis growers make to rural regions. [ABSTRACT FROM AUTHOR]

The vine mealybug, Planococcus ficus, is a global pest of grapes, leading to lower yields and transmission of damaging viral pathogens. Insecticides are the predominate method of P. ficus management, but some pesticide options have been lost in many of the world's vineyard regions and other economically viable options are now critically needed. Mating disruption is commercially available for P. ficus , however recommended deployment rates can be costly. To reduce costs, the effectiveness of lower dispenser deployment rates should be fully explored. In 2018–2019, we tested a novel high-density passive dispenser at 494 dispensers per ha. In 2020–2022 variable rates of the high-density dispenser were tested and a novel meso passive dispenser at variable rates was also tested in separate trails. An insecticide was applied to all treatments in 2018–2019 and to two of four blocks in 2020. All trials occurred in central California, US. The high-density dispensers (494 dispensers per ha) reduced male P. ficus captures and crop damage in both years. High-density dispensers at variable deployment rates (62–370 dispensers per ha) and meso dispensers (62–270 dispensers per ha) reduced P. ficus trap captures, with increasing dispenser density decreasing trap captures. Crop damage, amount of P. ficus per grape cluster, was significantly reduced only in the second year of the meso trial. Mating disruption is an effective method of suppressing P. ficus and current recommend rates could be lowered, which would reduce costs for growers and increase adoption of this sustainable tactic. • Mating disruption dispensers reduced Planococcus ficus trap catches with little to no insecticide application. • Mating disruption dispensers caused season long trap shutdown in three of the six trial/years. • One dispenser application was enough to affect trap catches for the entire season. • Grape cluster infestations were only reduced by mating disruption in one year. [ABSTRACT FROM AUTHOR]

Abstract: Mechanisms responsible for the success or failure of agricultural diversification are often unknown. Most studies of arthropod pest management focus on enhancing natural enemy effectiveness. However, non‐crop plants can also change crop host quality by reducing or adding soil nutrients or water, and therefore improve or hamper pest suppression. Native perennial ground covers may provide food or habitat to natural enemies and, in terms of competition for soil nutrients or water, be more compatible with crop management than exotic annuals. We conducted a 3‐year vineyard study to examine the impacts of native perennial grasses on pests, natural enemies, crop plant condition and soil properties. We included three ground cover treatments: bare soil with a grower standard drip irrigation; native grasses with drip irrigation; and native grasses with drip irrigation as well as an additional flood irrigation to keep the grasses green and growing during the season. Numbers of leafhopper pests Erythroneura spp. decreased in both native grass treatments, where parasitism rates were higher. Vine petiole nitrate levels were lower in grass treatments, indicating competition for soil nitrogen, which is most often considered to be detrimental. Berry weight was higher in the irrigated treatment but did not differ between the bare soil and non‐irrigated grass treatment. Grape °Brix was similar in the bare soil and native grass treatments, suggesting native grasses did not compromise grape quality. In fact, leaf water stress was lower and soil moisture higher not only in the irrigated grass treatment but, at times, in the non‐irrigated grass treatment, compared with the bare soil treatment. Synthesis and applications. Our work shows that native grasses contribute to a reduction in vineyard leafhopper pests by reducing host quality through competition for soil nitrogen and providing food resources and/or habitat for natural enemies. Native grasses also improve soil water content and may be part of a water conservation program for perennial crops in dry climate regions. [ABSTRACT FROM AUTHOR]

Pachycrepoideus vindemiae (Rondani) and Trichopria drosophilae (Perkins) are among a few indigenous parasitoids attacking the invasive Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in North America. Both parasitoid species occur in California, whereas only P. vindemiae has been reported from Oregon. We compared the thermal performance of the California populations of P. vindemiae and T. drosophilae , and the Oregon population of P. vindemiae at eight constant temperatures (12.6–32.8°C). Both P. vindemiae populations could develop at all tested temperatures. T. drosophilae failed to develop at or above 29.6°C. This species was, however, able to develop at a diurnal temperature regime of 15–32°C, and survival was higher in older developmental stages. T. drosophilae was less tolerant to both low and high temperatures than P. vindemiae , whereas the Oregon P. vindemiae population was more cold-tolerant but less heat-tolerant than the California population in terms of offspring survival, development, and reproduction. To develop storage strategies for mass-cultured parasitoids, we compared the cold tolerance of immature P. vindemiae and T. drosophilae of the California populations at 12°C for 1, 2, or 3 mo, followed by a 23°C holding period. Successful development to the adult stage decreased as cold storage duration increased. Successful development, however, increased when cold storage was initiated during the older developmental stages for 1-mo exposure for both parasitoid species. The results are discussed with regards to parasitoid thermal adaptation and the potential use of P. vindemiae and T. drosophilae for biological control of spotted-wing drosophila. [ABSTRACT FROM AUTHOR]

Grape growers in California utilize a variety of biological, cultural, and chemical approaches for the management of insect and mite pests in vineyards. This combination of strategies falls within the integrated pest management (IPM) framework, which is considered to be the dominant pest management paradigm in vineyards. While the adoption of IPM has led to notable and significant reductions in the environmental impacts of grape production, some growers are becoming interested in the use of an explicitly non-pesticide approach to pest management that is broadly referred to as ecologically-based pest management (EBPM). Essentially a subset of IPM strategies, EBPM places strong emphasis on practices such as habitat management, natural enemy augmentation and conservation, and animal integration. Here, we summarize the range and known efficacy of EBPM practices utilized in California vineyards, followed by a discussion of research needs and future policy directions. EBPM should in no way be seen in opposition, or as an alternative to the IPM framework. Rather, the further development of more reliable EBPM practices could contribute to the robustness of IPM strategies available to grape growers. [ABSTRACT FROM AUTHOR]

Some diseases manifest as one characteristic set of symptoms to the host, but can be caused by multiple pathogens. Control treatments based on plant symptoms can make it difficult to effectively manage such diseases, as the biology of the underlying pathogens can vary. Grapevine leafroll disease affects grapes worldwide, and is associated with several viral species in the family Closteroviridae. Whereas some of the viruses associated with this disease are transmitted by insect vectors, others are only graft-transmissible. In three regions of California, we surveyed vineyards containing diseased vines and screened symptomatic plants for all known viral species associated with grapevine leafroll disease. Relative incidence of each virus species differed among the three regions regions, particularly in relation to species with known vectors compared with those only known to be graft-transmitted. In one region, the pathogen population was dominated by species not known to have an insect vector. In contrast, populations in the other surveyed regions were dominated by virus species that are vector-transmissible. Our survey did not detect viruses associated with grapevine leafroll disease at some sites with characteristic disease symptoms. This could be explained either by undescribed genetic diversity among these viruses that prevented detection with available molecular tools at the time the survey was performed, or a misidentification of visual symptoms that may have had other underlying causes. Based on the differences in relative prevalence of each virus species among regions and among vineyards within regions, we expect that region and site-specific management strategies are needed for effective disease control. [ABSTRACT FROM AUTHOR]

Aim The role of landscape variation in shaping invasion success remains unclear, particularly for exotic predators. We examined whether native and exotic predators responded similarly or differently to ecological change at the landscape scale. Location Vineyards and surrounding natural habitat in the Napa Valley, California, USA. Methods We surveyed spider communities in vineyards throughout the Napa Valley and used regression analysis to examine the effects of landscape context (proportion of vineyard monoculture and proportion of developed land surrounding vineyards) on spider species richness and on numbers and proportions of exotic spiders. We also compared spider composition and dominance of exotic spiders between vineyards and surrounding natural habitat using non-metric multidimensional scaling ( NMDS). Results The success of the dominant exotic spider Cheiracanthium mildei was contingent on landscape context, and increased with proportions of vineyard and developed land in the surrounding landscape. Spider species richness and native spider abundance followed an opposing pattern. Cheiracanthium mildei was relatively unsuccessful near and in oak woodland, the primary type of natural habitat surrounding vineyards. Main Conclusions Results show that anthropogenic landscape change can have contrasting effects on native and exotic predators and that landscape context can influence the relationship between habitat modification and invasion success. Results suggest that it may be possible to limit the spread of invasions by increasing the availability of habitat for native species. [ABSTRACT FROM AUTHOR]

The mealybug Ferrisia gilli Gullan is a serious new pest of pistachios in California. It was first found near the town of Tulare in the late 1990s and has since spread to orchards in most pistachio-producing regions of the state. The seasonal phenology of F. gilli was evaluated in a commercial pistachio orchard in Tulare County during 2005 and 2006. During both seasons F. gilli overwintered as small nymphs and had three complete generations per year. Mealybug population densities were low and remained as immatures in March and April; by late May adult females formed and averaged (±SE) 1.3 ± 0.3 and 1.2 ± 0.3 per 0.75 m of sample branch in 2005 and 2006, respectively. The first in-season generation occurred from early June through mid--July, with mealybug densities ranging from 17.6 ± 5.6-26.4 ± 6.2 mealybugs per 0.75 m sample branch. The second in-season generation occurred from late July through September and had peak densities of 408.6 ± 93.9 and 182.0 ± 34.2 mealybugs per branch. In March and April mealybugs were located primarily on the buds and branch wood; in May the population was on branch wood as well as the rachis; from June through September the population was located primarily in the pistachio cluster. F. gilli's seasonal phenology described herein was used to develop a management program. [ABSTRACT FROM AUTHOR]

The parasitoid Psyttalia humilis (Silvestri) was reared on Mediterranean fruit fly, Ceratitis capitata (Wiedemann), third instars irradiated at 0-70 Gy at the USDA, APHIS, PPQ, Moscamed biological control laboratory in San Miguel Petapa, Guatemala, and shipped to the USDA, ARS, Parlier, CA. Irradiation dose did not affect the parasitoid's offspring sex ratio (53-62% females), percentage of unemerged adults (12-34%), number of progeny produced per female (1.4-1.8), and parasitism (19-24%). Host irradiation dose had no significant effect on the forewing length of female P. humilis and its parasitism on olive fruit fly, Bactrocera oleae (Rossi) and offspring sex ratio, but dissection of 1-wk-old female parasitoids reared from hosts irradiated with 70 Gy had a significantly lower number of mature eggs than females from nonirradiated hosts. Longevity of P. humilis adults decreased with increased temperature from 15 to 35°C, regardless of food provisions, gender, and host irradiation dose. Females survived 37- 49 d at 15°C with water and food, and only 1-2 d at 35°C without food, whereas males lived shorter than females at all temperatures and food combinations tested. Adult P. humilis reared from fertile C. capitata and aspirated for dispensing in cups lived significantly longer after shipment than those specimens chilled and dispensed by weight. At 21 and 32°C, 50% of parasitoids departed release cages after 180 and 30 min, respectively, but none departed at 12°C. Thirteen shipments of P. humilis (2,980-21,922 parasitoids per shipment) were received between September and December 2009, and seven shipments (7,502-22,560 parasitoids per shipment) were received between October and December 2010 from San Miguel Petapa, Guatemala. Daily number of olive fruit fly adult and percentage female trap captures ranged <1-19 and 8-58% in 2009, and <1-11 and 0-42% in 2010, respectively. The number of parasitoids released ranged 848-12,257 in 2009 and 3,675-11,154 in 2010. Percentage parasitism of olive fruit fly third instars at all locations ranged 0-9% in 2009 and 0-36% in 2010. [ABSTRACT FROM AUTHOR]

The light brown apple moth, Epiphyas postvittana (Walker), an Australia native tortricid, was found in California in 2006. A field survey of host plants used by E. postvittana was conducted in an urban region of the San Francisco Bay Area. An inspection of 152 plant species (66 families), within a 23-ha residential community, found E. postvittana on 75 species (36 families). Most (69 species) host plants were not Australian natives, but had a wide geographic origin; 34 species were new host records for E. postvittana. Heavily infested species were the ornamental shrubs Myrtus communis L., Pittosporum tobira (Thunb.) W.T. Aiton, Euonymus japonicus Thunb., and Sollya heterophylla Lindl. To survey for parasitoids, four urban locations were sampled, with E. postvittana collected from five commonly infested plants [M. communis, P. tobira, E. japonicus, Rosmarinus officinalis L., and Genista monspessulana (L.) L.A.S. Johnson]. Twelve primary parasitoid species and two hyperparasitoids were reared; the most common were the egg parasitoid Trichogramma fasciatum (Perkins), the larval parasitoids Meteorus ictericus Nees, and Enytus eureka (Ashmead), and the pupal parasitoid Pediobius ni Peck. Meteorus ictericus accounted for >80% of the larval parasitoids, and was recovered from larvae collected on 39 plant species. Across all samples, mean parasitism was 84.4% for eggs, 43.6% for larvae, and 57.5% for pupae. The results are discussed with respect to the potential for resident parasitoid species to suppress E. postvittana populations. [ABSTRACT FROM AUTHOR]

Almond leaf scorch (ALS) disease is caused by the bacterium Xylella fastidiosa and transmitted by xylem-feeding insects. Reports of increased incidence of ALS-diseased trees in California prompted surveys in three almond LPrunus dulcis (Mill.) D.A.Webb]-growing regions, from June 2003 to September 2005, to determine insect vector species composition and abundance. For comparison, sampling in and near vineyards in the San Joaquin Valley, California, also was completed. Sampling in or near almond orchards collected >42,000 Cicadomorpha of which 4.8% were xylem feeders, including 1,912 grass sharpshooter, Draeculaccphaia minerva Ball; five Xyplion fulgida Nottingham; and a single spittlebug, Philaenus spwnarivs L. The most abundant vector was 1). minerva. Season-long sampling indicated that D. minerva was a year-round resident in and/or near almonds in the Sacramento Valley, but not in the San Joaquin Valley. Similarly, D. minerva was rare in vineyards in the San Joaquin Valley, but was abundant in irrigated pastures near vineyards. D. minerva was most frequently collected along orchard margins, and peak densities were observed in summer, the period of time when bacterial titers are reported to increase in infected trees. Screening of D. minerva for presence of X.fastidiosa found that 1.1% of insects collected near almond orchards and 4.5% of insects collected from pastures tested positive. The X.fastidiosa subspecies and genotype detected in insects collected from orchards matched those collected from ALS-diseased almond trees in the same orchard. Of the few X. fulgida and P. spuinarius collected, none tested positive for X. fastidiosa. Results are discussed with respect to X. fastidiosa vector control and detection methods. [ABSTRACT FROM AUTHOR]

The larval parasitoid, Psyttalia humilis (Silvestri), reared on Mediterranean fruit fly, Ceratitis capitata (Weidemann), by USDA-APHIS-PPQ, San Miguel Petapa, Guatemala was imported into California for biological control of olive fruit fly, Bactrocera oleae (Rossi). This study reports the results of field releases and recovery of P. humilis in California, and laboratory investigations to determine the effects of food provision, high temperature, and insecticidal bait spray on the parasitoid's survival and fecundity. Parasitoids (3,613-7,823) were released in Orland, San Juan Bautista, Cayucos, Sylmar, Santa Barbara, and San Diego during October through December 2006. Mean daily temperatures at the release sites ranged from 10.7°C in Orland to 20.9°C in San Juan Bautista. The lowest (0.5) and highest (29.7) mean number of adult B. oleae per day per trap was captured in Orland and Sylmar, while the lowest (0.01) and highest (2.21) number of third instar larvae per fruit was collected on 11 December in Orland and on 5 October in San Diego in prerelease samples, respectively. Parasitoids were recovered from all release sites, the lowest (0.3%) and highest (100%) parasitism occurred on 25 January in Sylmar and on 26 October in Cayucos, respectively. At 24°C, parasitoids reared from B. oleae larvae survived 36 d on honey, 31 d on orange juice, and 28 d on honeydew, which was significantly longer than on cut olive fruit (8 d) or without food (11 d), but was similar to those reared from C. capitata larvae under the same food conditions. Under a high diurnal temperature regime (18.3-35°C) reflecting the summer olive growing conditions in the California Central Valley, the parasitoids survived <5 d when no food or only water was provided. Its longevity and life-time fecundity significantly increased by provision of honey or honeydew. There was no difference in the parasitoid's longevity between females and males or between food and sexes. Percent mortality of parasitoid adults was not significantly affected by the exposure to insecticidal fruit fly bait (GF-120) in four different types of choice tests with artificial honeydew and GF-120. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the persistence of nonnative and native spiders in California's agricultural landscape. Results of the study suggest that a key source for vineyard spiders is the natural habitat. It says that strong habitat preferences and dispersal limitation may have kept native spiders from establishing away from the edge of the vineyard.

The article offers information on the effort of California researchers to provide adequate control of olive fruit fly in the state. The started a worldwide search for parasitoids with exploration in several countries such as Republic of South Africa, Namibia,and India. It mentions that parasitiods were shipped to California and studied in quarantine to determine the best species for release. It notes that two best species are already released and are being studied for their effectiveness.

The article offers information on field studies indicating that trap counts for olive fruit fly adults in pesticide-free sites decrease in mid and late summer and then increase from September to November in California's Central Valley. It states that a portion of the decline is linked with heat stress that the flies experience during mid and late summer. Furthermore, the adult flies will die in a few days of having no adequate amounts of water and carbohydrates.

Eucalyptus spp., native to Australia, have been introduced into many parts of the world as important timber and ornamental trees. Although the trees have important silvicultural qualities, they also have generated intense dissatisfaction, particularly among groups of individuals in California. The trees have benefited from the lack of insect pests and diseases in their adventive ranges but that has changed over the past four decades. In California, two species of insect herbivores were introduced between the time trees were first introduced to the state in the middle of the 19th century and 1983, Between 1983 and 2008, an additional 16 Australian insect pests of eucalyptus have become established in the state. The modes or routes of introduction have never been established. However, examinations of different temporal and spatial patterns suggest that the introductions were nonrandom processes. It is possible that they occurred because of increased trade or movement of people, but the hypothesis that there were intentional introductions also must be considered. The rapid accumulation of introduced herbivores on an ornamental plant system in a single state is a cautionary example of what could happen if a major food or fiber crop were intentionally targeted. [ABSTRACT FROM AUTHOR]

In laboratory experiments, a flameless catalytic infrared emitter, fueled by propane, was used to disinfest hard red winter wheat, Triticum aestivum L., containing different life stages of the lesser grain borer, Rhyzopertha dominica (F.), an economically important insect species associated with stored wheat in Kansas. The emitter generates infrared radiation in the 3-7-μm range. The life stages of R. dominica exposed to infrared radiation included eggs, larvae in different stages of development, pupae, and 2-wk-old adults. A noncontact infrared thermometer measured grain temperatures continuously during exposures of infested wheat to infrared radiation. The grain temperatures attained were influenced by wheat quantity; distance from the emitter; and exposure time, which in turn influenced effectiveness against various life stages of R. dominica. In general, higher grain temperatures were attained in 113.5 g of wheat as opposed to 227.0 g, and at 8.0 cm from the emitter surface rather than at 12.7 cm, and during a 60-s exposure compared with a 45-s exposure. Logistic regression indicated the probability of death of various life stages of R. dominica was temperature dependent. The log odds ratios showed old larvae were less susceptible to infrared radiation than young larvae. Approximately ≥94% mortality of all R. dominica life stages occurred when using 113.5 g of wheat, exposed for 60 s at a distance of 8.0 cm from the emitter, resulting in mean ± SE wheat temperatures that ranged between 107.6 ± 1.4 and 113.5 ± 0.5°C. Our results with small grain quantities show flameless catalytic infrared technology to be a promising tool for disinfestation of stored wheat. [ABSTRACT FROM AUTHOR]

We evaluated the relationships between plant water status and leaf temperature, and between leaf temperature and spider mite (Acari: Tetranychidae) and predatory mite (Acari: Phytoseiidae) populations in eight vineyards in California in 2006 and 2007. Temperature of south-facing leaves increased significantly by 0,8°C for every 1.0°C increase in ambient air temperature, and by 5.3°C for every one MPa drop in leaf water potential. Peak population densities of Pacific spider mite, Tetranychus pacificus McGregor, increased significantly with increasing frequency of leaf temperatures above 31°C. In contrast, peak population densities of Willainette spider mite, Eotetranychus willamettei (McGregor),showed no relationship with the frequency of leaf temperatures above 31°C. This differential relationship between the two mite species and high leaf temperatures is consistent with their upper thresholds for development, which are 40°C for T. pacificus and 31°C forE. willamettei, as identified in a previous study. Predatory mite population densities showed no relationship with peak population densities of either spider mite species during the analysis period, but decreased with the frequency of leaf temperatures above 31°C. In addition, predatory mite population densities were significantly higher on south-facing than interior leaves after adjusting for the effect of leaf temperature. These results help to explain why outbreaks of T. pacificus occur in warmer or water-stressed vineyards, whereas E. willamettei develops higher populations in cooler or well-irrigated vineyards. In addition, these results suggest that regulated deficit irrigation should be implemented with caution, especially in those vineyards with a high risk of T. pacificus outbreaks. [ABSTRACT FROM AUTHOR]

Abstract: Many generalist predators do not persist in crops year-round, and must colonize crops on a seasonal basis from natural vegetation. We monitored the spider community in the air, on the ground, and in the foliage of California vineyards and neighboring oak-woodlands, to assess whether dispersal from natural habitats influences the abundance and species diversity of spiders in agroecosystems. Early in the growing-season, low spider numbers in vineyard foliage indicated that few spiders overwintered in the vineyard. Aerial dispersal did not, however, occur primarily in the spring when generalist predators are likely to be important in pest suppression, but in mid-summer, while dispersal activity on the ground did not change over time. Aerial collection traps showed greater similarity to spider composition in vineyard foliage than ground collection traps, indicating that spiders in vineyards disperse more by air than over ground. Dwarf spiders (Linyphiidae) dominated spider composition on aerial traps but were not abundant on the vine, while other spider species showed an opposing pattern, suggesting that while spiders may have entered vineyards by air, other factors may have also contributed to spider composition in vineyards. These results are discussed with respect to control of vineyard pests and the establishment of spiders in vineyard agroecosystems. [Copyright &y& Elsevier]

The olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is an invasive pest in California. Identifying environmental constraints that affect the geographic distribution and abundance of any invasive insect pest is fundamental to its effective management. California's Central Valley, where most commercial olives are grown, is extremely hot during the summer, with maximum daily temperatures consistently >35.0°C. This study examined the effects of two diurnal temperature regimens (low 18.3°C, high 35.0 or 37.8°C) reflecting summer conditions in the valley, and one control temperature regimen (low 18.3°C, high 23.9°C) on the fly's survival and reproductive success in the laboratory. The temperature regimen of 18.3-35.0°C resulted in delayed egg maturation and reduced production of mature eggs compared with the control temperature regimen. Egg maturation was possible at the higher temperature regimen when females were provided with water and food, and egg-laying occurred during the cold phase of the temperature cycle. Access to olive fruit and oviposition itself further promoted egg maturation. Under exposure to the 18.3-35.0°C temperature regimen, ≈50% of eggs died, and the remainder that hatched died as first instars. No egg hatch occurred at the temperature treatment of 18.3-37.8°C. We confirmed these laboratory results through field cage studies with adult B. oleae, conducted in the summer of 2007 and 2008. Under ambient summer temperatures, adult B. oleae survived for 1-2 wk, and females readily laid eggs when provided water and food. No offspring developed in midsummer of 2007, and <2% of the offspring developed to adults in summer 2008 trials. These results suggest that high summer temperatures limit the fly's abundance in California's Central Valley. [ABSTRACT FROM AUTHOR]

Non-target risk posed by an African parasitoid, Bracon celer Szepligeti (Hymenoptera: Braconidae), was assessed for a classical biological control program against olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae: Dacinae), in California, USA. Behavioral and reproductive responses to non-target tephritid species were tested with beneficial (Chaetorellia succinea [Costa] and Parafreutreta regalis Munro) (Tephritidae: Tephritinae) and native (Rhagoletis fausta [Osten Sacken]) (Tephritidae: Trypetinae) fruit fly species in successive no-choice and choice experiments under close confinement in quarantine. Non-target host-plant substrates exposed to B. celer were yellow-starthistle flower heads containing C. succinea, Cape ivy stem galls containing P. regalis, and bitter-cherry fruit containing R. fausta. The parasitoid probed all three infested non-target plant substrates, but significantly less than olives infested with B. oleae. It produced offspring from P. regalis in Cape ivy stem galls, but appeared unable to penetrate yellow-starthistle flower heads with its ovipositor. Bracon celer killed some B. oleae and R. fausta larvae without parasitism. Reproduction on P. regalis indicates that B. celer has a broad physiological host range, which, combined with the parasitoid's acceptance of all three host-plant substrates, indicates a strong potential to negatively impact non-target species. Although physical and temporal barriers to host attack may reduce risk to most non-target tephritids by B. celer in California, the parasitoid should not be released due to its risk of harming the beneficial P. regalis. Release of P. regalis is still under consideration, however, and final risk assessment should depend on whether the fly proves useful for weed control. [ABSTRACT FROM AUTHOR]

The mealybug, Planococcus ficus (Signoret), is one of the more damaging vineyard pests and an important vector of Grapevine leafroll-associated viruses. Pheromone-mediated mating disruption is a commercially available and environmentally sustainable control tool for P. ficus. Here we report on a three-year areawide study of P. ficus mating disruption in Napa County, California, where pheromone dispensers were deployed across large (53–66 ha) multi-owner sites that were paired with sites that did not receive pheromone. Male P. ficus captures in pheromone traps were correlated with mealybug numbers and crop damage, and were useful in identifying 'hotspots' to be targeted with insecticide applications for areawide control. Trap catches at mating disruption sites were far lower than untreated sites, although mealybugs were still present at mating disruption sites. Evidence indicated that mating disruption reduced P. ficus density and spread, particularly in areas with low initial mealybug densities. In the third year, areawide mating disruption was discontinued at the former mating disruption sites and, as evidence of its impact, P. ficus trap captures increased. These results suggest that mating disruption and well-timed, effective insecticide applications play complementary roles, and that monitoring the areawide distribution of pests is a critical component of programs for controlling P. ficus. • Pheromone traps were useful in identifying 'hotspots' of the mealybug Planococcus ficus. • Mating disruption appeared to limit Pl. ficus density and spread over large vineyard areas. • Effects of mating disruption were most pronounced in areas with low mealybug densities. • Pl. ficus trap captures increased at most sites after mating disruption was discontinued. • Mating disruption and insecticides likely play complementary roles in Pl. ficus control. [ABSTRACT FROM AUTHOR]

Liquid baits were evaluated for control of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), and associated mealybug and soft scale pests in California vineyards. In 2003, liquid baits with small doses of imidacloprid, boric acid, or thiamethoxam dissolved in 25% sucrose water resulted in lower ant and mealybug densities and fruit damage, compared with an untreated control. Similar treatments in a soft scale-infested vineyard showed only a reduction of ant density and fruit infestation in only the boric acid and thiamethoxam treatments. In 2004, commercial and noncommercial formulations of liquid baits reduced ant densities in three separate trials, but they had inconsistent effects on mealybug densities and fruit infestation; granular protein bait had no effect. Using large plots and commercial application methodologies, liquid bait deployed in June resulted in lower ant density and fruit infestation, but it had no effect on mealybug density. Across all trials, liquid bait treatments resulted in lower ant density (12 of 14 trials) and fruit damage (11 of 14 sites),presenting the first report of liquid baits applied using commercial methodologies that resulted in a reduction of ants and their associated hemipteran crop damage. For commercialization of liquid baits, we showed that any of the tested insecticides can suppress Argentine ants when properly delivered in the crop system. For imidacloprid, bait dispensers must be protected from sunlight to reduce photodegradation. Results suggest that incomplete ant suppression can suppress mealybug densities. However, after ant populations are suppressed, there may be a longer period before hemipteran populations are effectively suppressed. Therefore, liquid baits should be considered part of a multiseason program rather than a direct, in-season control of hemipteran pest populations. [ABSTRACT FROM AUTHOR]

1. Vine mealybug Planococcus ficus is an invasive pest of vineyards in many areas of the world. In California, USA, it infests all plant subunits and has a spatial refuge from natural enemies under the bark and on roots. A temporal refuge is created when ants tending the mealybug reduce the efficacy of natural enemies. 2. Biological control of vine mealybug is only partially successful and varies among California grape-growing regions. To improve control and help determine appropriate natural enemies for importation, the effects of weather on mealybug regulation by two parasitoids, Anagyrus pseudococci and Leptomastidea abnormis, and a coccinellid predator, Cryptolaemus montrouzieri, were examined across the ecological regions of California. 3. Weather-driven, physiologically based age–mass structured demographic models of the mealybug and its natural enemies were parameterized using laboratory data and field observations. Temperature was used to define the thermal limits and development rates of each species, and resource supply/demand ratios were used to scale daily per capita growth, fecundity and survivorship rates from maximal values at optimal conditions. 4. The population dynamics of the mealybug and its natural enemies were simulated at 108 locations in California over a 10-year period using observed weather. The simulation data were mapped using a geographical information system (GIS) and analysed using linear multiple regression and marginal analysis. 5. The models predictions indicated that: (i) the parasitoid A. pseudococci has a larger impact on vine mealybug than either L. abnormis or C. montrouzieri; (ii) mealybug densities will be lowest in the hot desert regions of southern California and highest in the cooler areas of northern California; (iii) mealybug density increases with season length and the size of the combined spatial–temporal refuge; (iv) biological control of mealybug could be achieved by reducing the size of the spatial–temporal refuge. 6. Synthesis and applications. Models, no matter how detailed, will always be incomplete; despite this, the complexity of tri-trophic systems can be modelled and the effects of biotic factors and of weather separated. The predictions of our model coincided well with field observations on vine mealybug, and clearly showed why the biological control will require additional species of natural enemies and/or why the size of the spatial and temporal refuges must be reduced. [ABSTRACT FROM AUTHOR]

Controlling navel orangeworm, a key pistachio pest, is problematic because the moth overwinters in "mummy" nuts. After harvest, there may be more than 30,000 pistachio nuts (mummies) left behind per acre. To provide better in formation for winter sanitation decisions, we investigated the number of available mummies and their levels of navel orangeworm infestation from winter through early summer in California pistachio orchards. Navel orangeworm mortality was highest from late December through mid-February, and was also higher on the ground than in trees. Mortality on the ground was highest when mummies were tilled or mowed with the groundcover than when nuts were left on the raised berm. Our data indicates that, in contrast to almonds, it is more productive to focus on clearing pistachios from the ground than on removing them from trees. However, winter sanitation procedures also should be augmented in order to destroy more overwintering navel orangeworm. [ABSTRACT FROM AUTHOR]

Efforts to control the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae), in California have focused on insecticidal baits and biological control by parasitoids, which primarily target the adult and larval stages, respectively. The pupal stage, which occurs in the soil, has largely been overlooked. This study investigated mortality factors for olive fruit fly pupae in California olive orchards, using a combination of exclusion experiments and observation and trapping of potential predators. Results show predation and climatic factors contribute to pupal mortality. Ants (Formicidae) were the most numerous predators observed. Soil-borne pathogens caused no mortality in this study. Potential applications of these results in the development of a sustainable management program are discussed. [ABSTRACT FROM AUTHOR]

Experiments were conducted to test a mating disruption program for the mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) in California vineyards. The sprayable, microencapsulated formulation of the racemic sex pheromone lavandulyl senecioate was applied with an air-blast sprayer, using three and four applications in 2003 and 2004, respectively. Mating disruption was combined with an application of buprofezin (2004) in June. Compared with a no-pheromone control, there were significantly lower season-long trap catches of adult males, season-long mealybug densities (2003 only), and crop damage in mating disruption plots. The amount of mealybug reduction and mechanisms that resulted in lower crop damage in mating disruption plots is discussed. In samples taken during the growing season (April to September), mealybug density was only 12.0 ± 15.6 and 31.1 ± 11.6% lower in the mating disruption plots than in control plots in 2003 and 2004, respectively. In the mating disruption treatment, mealybug egg production was significantly lower (2003 only), as were the proportion of ovisacs and crawlers produced. There was no treatment impact on percentage of parasitism. Mealybug density influenced treatment impact. In 2004, vines were categorized as having low, medium, or high mealybug densities during a preapplication survey. After treatment application, mealybug density was reduced by 86.3 ± 6.3% on vines in the low mealybug density category, but it was unchanged on vines in the high density category. Another factor that reduced treatment impact was the relatively short effective lifetime of the sprayable formulation. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa is a xylem-limited bacterium that causes almond leaf scorch (ALS), Pierce's disease of grapevines, and other plant diseases. We surveyed ground vegetation in ALS-infected almond orchards in California's Central Valley for the presence of this bacterium. Plant tissue samples were collected throughout a 2-year period and processed for the presence of X. fastidiosa using restriction enzyme digestion of RST31 and RST33 polymerase chain reaction (PCR) products and bacterial culture on selective media. Overall disease incidence was low in the ground vegetation species; only 63 of 1,369 samples tested positive. Of the 38 species of common ground vegetation tested, 11 tested positive for X. fastidiosa, including such common species as shepherd's purse (Capsella bursa-pastoris), filaree (Erodium spp.), cheeseweed (Malva parvifolia), burclover (Medicago polymorpha), annual bluegrass (Poa annua) London rocket (Sisymbrium irio), and chickweed (Stellaria media). There was a seasonal component to bacterial presence, with positive samples found only between November and March. Both ground vegetation and almond trees were most commonly infected with the almond strain of X. fastidiosa (six of seven surveyed sites). ALS-infected almond samples had an X. fastidiosa concentration within previously reported ranges (1.84 × 106 to 2.15 × 107 CFU/g); however, we were unable to accurately measure X. fastidiosa titer in sampled ground vegetation for comparison. These results are discussed with respect to ground vegetation management for ALS control. [ABSTRACT FROM AUTHOR]

To aid in identifying key predators of Proconiini sharpshooter species present in California, we developed and tested molecular diagnostic markers for the glassy-winged sharpshooter, Homalodisca coagulata (Say), and smoke-tree sharpshooter, Homalodisca liturata (Ball) (Homoptera: Cicadellidae). Two different types of markers were compared, those targeting single-copy sequence characterized amplified regions (SCAR) and mitochondrial markers targeting the multicopy cytochrome oxidase subunit genes I (COI) and II (COII). A total of six markers were developed, two SCAR and four mitochondrial COI or COII markers. Specificity assays demonstrated that SCAR marker HcF5/HcR7 was H. coagulata specific and HcF6/HcR9 was H. coagulata/ H. liturata specific. COI (HcCOI-F/R) and COII (HcCOII-F4/R4) markers were H. coagulata specific, COII (G/S-COII-F/R) marker was H. coagulata/ H. liturata specific, and lastly, COII marker (Hl-COII-F/R) was H. liturata specific. Sensitivity assays using genomic DNA showed the COI marker to be the most sensitive marker with a detection limit of 6 pg of DNA. This marker was 66-fold more sensitive than marker Hl-COII-F/R that showed a detection limit of 400 pg of DNA. In addition, the COI marker was 4.2-fold more sensitive than the COII marker. In predator gut assays, the COI and COII markers demonstrated significantly higher detection efficiency than the SCAR markers. Furthermore, the COI marker demonstrated slightly higher detection efficiency over the COII marker. Lastly, we describe the inclusion of an internal control (28S amplification) for predation studies performing predator gut analyses utilizing the polymerase chain reaction (PCR). This control was critical in order to monitor reactions for PCR failures, PCR inhibitors, and for the presence of DNA. [ABSTRACT FROM AUTHOR]

The olive fruit fly, Bactrocera oleae (Tephritidae), is a significant threat to California's olive industry. As part of a classical biological control program started in 2002, the parasitoids Diachasmimorpha kraussii and D. longicaudata (Hymenoptera: Braconidae) were imported to California from laboratory colonies in Hawaii. Studies on their biology and behavior as parasitoids of the olive fruit fly were conducted in quarantine. Both species tend to oviposit into 2nd and young 3rd instars, with the offspring completing development in the flies’ puparia. Most eggs are deposited in the first two weeks of adult life. Observed lifetime fecundity was low, possibly as a consequence of the relatively poor quality of the harvested olives used as a host substrate. Both pre-imaginal development and adult longevity were limited at constant temperatures above 30°C, which may indicate that these species will have difficulty establishing in the warmest regions of California. [ABSTRACT FROM AUTHOR]

Psyllaephagus bliteus was imported from Australia in 1999 and released in California in 2000 as part of a classical biological control program targeting the red-gum lerp psyllid, Glycaspis brimblecombei, which in California feeds mainly on red gum, Eucalyptus camaldulensis Dehnh. Psyllaephagus bliteus is an internal parasitoid that delays development until the psyllid host reaches the late fourth or fifth instar. It pupates within the remains of the host, enclosed in three distinct layers. First, parasitised G. brimblecombei produce lerps with basal walls that are significantly thicker than those of unparasitised psyllids. Second, the parasitised psyllid mummifies soon after P. bliteus begins to pupate. Third, a highly melanised pupal sheath is produced that completely envelops the pupal P. bliteus. Photographs are provided and observations on the pupal sheath, which has seldom been described for any parasitoid, are compared with earlier descriptions. We discuss the function of each of the three layers with respect to the protection of the immobile P. bliteus pupa from the environment or natural enemies. [ABSTRACT FROM AUTHOR]

The article investigates the new control tools to be used against the vine mealybug, a newly invasive pest that has spread throughout California's extensive grape-growing regions. Vineyard mealybug decreases crop quality by excreting honeydew, which promotes sooty molds, and by infesting grape bunches. According to the study, it has biological characteristics that make it more damaging than other vineyard mealybugs.

Cites a study which found that imported parasitic wasps helps control red gum lerp psyllid in California. Effect of this psyllid on eucalyptus species; Importation of the new parasitoid species from Australia; Approach used by researchers in finding promising parasitoids.

Simple Summary: In California, grape cultivation for wine, juice, fresh and raisin markets is one of the most profitable agricultural sectors. Pathogens, weeds and insect pests cause millions in crop loss and result in additional costs through the use of pesticides and other control tools. Here, we report on the emergence of a new California grape pest, the carpentermoth Givira ethela (Neumoegen and Dyar, 1893). This paper also aimed at the moth's identification through molecular and morphological features and updates the distribution of G. ethela in California. Furthermore, the presence of G. ethela larval galleries appears to facilitate the mealybug pest Planococcus ficus Signoret, 1875, providing better access to vine sap and protection from natural enemies, environmental stresses, and pesticide treatments. We propose that management practices against G. ethela should include the correct identification of the pest and of its damage, but also the investigation of monitoring methods, economic thresholds, biological controls, and a better understanding of the relationship between G. ethela and P. ficus or other mealybug pest species. Grape cultivation is a billion-dollar agricultural sector in California, where invasive or novel pest species can disrupt management practices. We report herein on a new pest associated with California vineyards, the carpentermoth Givira ethela (Neumoegen and Dyar, 1893). Rather than an invasive species, G. ethela appears to be a newly recognized wood-boring pest of Vitis vinifera (L.) in regions of California's Central Valley, where its initial occurrence has been dated back to, at least, the beginning of the 2000s. The habitus of adult, genitalia and pupa is illustrated. Givira ethela distribution in California is updated including published records and new data. Carpentermoth galleries seem to facilitate the access of Planococcus ficus Signoret, 1875 to vine sap and protection from natural enemies, environmental stresses, and pesticide treatments. Notes on pest status, life history, monitoring practices, natural enemies, and management options on grapes are also discussed. Tools for the Integrated Pest Management of G. ethela should include the correct identification of the insect and its damage, a full understanding of its biology and ecology, the application of monitoring methods, and the identification of economic thresholds and injury levels. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown marmorated stink bug is native to Asia and has invaded parts of Europe and North America where it causes considerable damage to a wide range of vegetable, fruit, and nut crops. Pistachios have become an important nut crop in California, and as this invasive stink bug moved into California, farmers needed to know about the potential damage from brown marmorated stink bugs. Here, we assessed pistachio yield loss and nut damage over a two-year period. The invasive stink bug was also compared with the native green stink bug and a native leaffooted bug. We found that brown marmorated stink bug adults cause more epicarp lesions (external damage) when recorded at harvest time than the native species; however, they did not cause more kernel necrosis (internal damage) than the two native species tested, which is a more relevant damage criterion for commercial production. We conclude that the brown marmorated stink bug could cause similar damage as the native species but note that the invasive stink bug's numbers in California are still low and future damage levels will be dependent on this pest's population density. California currently produces about a quarter of the world's pistachios. Pistachio nuts are susceptible to feeding by stink bugs and leaffooted bugs; therefore, the invasive presence of the highly polyphagous brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a concern to California pistachio growers. We aimed to assess the potential of H. halys to cause yield loss and nut damage to pistachios, which had not yet been assessed in the field. Over two years, terminal branch ends with pistachio clusters were enclosed in organdy cages from spring to fall and exposed to either H. halys, the native stink bug Chinavia hilaris Say (Hemiptera: Pentatomidae), or leaffooted bug Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae), for 4–7-day feeding periods at different times of the season. We found that H. halys adults cause more epicarp lesions (external damage) when recorded at harvest time than the native species. They did not, however, cause more kernel necrosis (internal damage) than the two native species tested, which is a more relevant damage criterion for commercial production. There were no differences among insect species for any other recorded damage criteria. We conclude that H. halys could cause similar damage as the native species but note that H. halys population densities in California are still low and future damage levels will be dependent on this pest's population density. [ABSTRACT FROM AUTHOR]

The leaffooted bug, Leptoglossuszonatus (Heteroptera: Coreidae), has become a key pest of almonds, pistachios, and pomegranates in California. Adults and nymphs directly feed on nuts and fruits, which reduces crop yield and quality and can facilitate pathogen infections. Current monitoring strategies require growers to actively sample the tree canopy, with no economic thresholds being developed for this pest. To improve monitoring of L.zonatus, a three-year study was conducted to identify an optimal trap. A hanging cross-vane panel trap was identified as the best trap type in Year 1, and subsequent work in Years 1–3 focused on refining its use by modifying surface texture and color. Results indicated that coating trap surfaces with the lubricant fluon improved trap catching ability, and adults were most frequently recovered in yellow traps. A hanging cross-vane panel trap with these features could serve as the basis for the development of a new monitoring system for this pest in orchards, which could be improved further if semiochemical lures will be developed. [ABSTRACT FROM AUTHOR]

The olive psyllid, Euphyllura olivina, is a newly invasive species to California with the potential to become an economical pest if it reaches the olive production regions of California's Central Valley. Here, we report on surveys undertaken in California to assess the psyllid's current distribution and the occurrence of parasitism. Additionally, we present results of foreign collections of its parasitoids and initial non-target studies of a possible biological control agent, the Mediterranean parasitoid Psyllaephagus euphyllurae. The current distribution of the psyllid appears to be limited to the California coast between Monterey and San Diego; there have been no reports of infestations on olives in the major production areas of central and northern California. Psyllaephagus euphyllurae was the major primary parasitoid found in our foreign collections. The potential non-target impact of P. euphyllurae was tested on three native North American psyllid species: Neophylluraarctostaphyli, Euglyptoneura nr. robusta, and Calophyanigrella. No P. euphyllurae developed on the non-target species during no-choice tests. Behavioral observations in choice tests confirmed no attack on the non-target hosts, although the parasitoid did remain longer on N. arctostaphyli-infested manzanita plants, and revealed no host feeding behavior. [ABSTRACT FROM AUTHOR]

Leptoglossus zonatus is a polyphagous pest found throughout much of the Western Hemisphere. In California, L. zonatus attacks almond, pistachio, pomegranate, and walnut crops, but the seasonal use of and economic damage to these crops varies. To better understand the seasonal changes of L. zonatus populations and to improve monitoring programs in California's San Joaquin Valley, we caged overwintering adult males and females and then followed the resulting population dynamics over a one-year period. There were three generations over the one-year period, although eggs, nymphs, and adults overlapped among successive generations. From an initial 75 overwintering adult females, there were 1214 egg strands, 16,692 nymphs, and 4900 adults recorded during the one-year period. Depending on the generation, the number of nymphs per egg strand ranged from 11.3 to 14.3; the sex ratio was close to 1:1 with the exception of one female-biased cage; and nymph mortality ranged from 22.0% to 39.5%. Adult females isolated from each generation produced 2.4–5.1 egg strands per female that totaled 41.7–61.7 eggs per female with a 67.1–86.8% successful hatch rate. We find that the adult is the overwintering stage, as more adults (without food provisions) survived the winter compared to medium-sized or large-sized nymphs provided with both food and water. The results are discussed with respect to the development of L. zonatus control and monitoring programs for California's multi-billion-dollar (US) nut crops. [ABSTRACT FROM AUTHOR]

A major challenge to the area-wide management of Drosophila suzukii is understanding the fly's host use and temporal dynamics, which may dictate local movement patterns. We determined D. suzukii's seasonal host use in California's San Joaquin Valley by sampling common crop and non-crop fruits in a temporal sequence of fruit ripening. We then evaluated the suitability of selected fruits as hosts. Drosophila suzukii emerged from both intact and damaged cherries during the cooler, early season period. Fly density remained low through the hot spring–summer period and re-surged as temperatures lowered in fall when the fly did not cause damage to intact peach, nectarine, plum, pear, grape, pomegranate, apple, persimmon and citrus (in order of ripening) but did emerge from the damaged fruits of these crops. The fly also emerged from two ornamental fruits (loquats and cactus) but was not found on wild plum and two endemic wild fruits (buckthorn and bitter berry). Drosophila suzukii completed development (egg to adult) on cactus, mandarin carpel, pomegranate seed, wild plum and buckthorn at survival rates similar to cherry (51.2–68.8%), whereas it had a lower survival rate on bitter cherry (33.2%), table grape (31.5%), raisin grape (26.5%), and wine grape (4.5%). The high acidity levels of grapes negatively affected the fly's fitness. Among 10 cherry cultivars, survival rate was not affected by sugar content, but it decreased with increasing egg density per gram of fruit. Results suggest that in California's San Joaquin Valley, the early season crops are most vulnerable, summer fruits ripen during a period of low pest pressure, and late season fruits, when damaged, serve to sustain D. suzukii's populations in this region. [ABSTRACT FROM AUTHOR]

Abstract: Gonatocerus ashmeadi Girault is an egg parasitoid with potential use in glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), biological control in California. We tested the hypotheses that (1) G. ashmeadi uses chemical volatiles as cues to find hosts, (2) its success in host finding varies among plant species, and (3) the release of semiochemicals is systemically induced by GWSS feeding and oviposition. Using a glass Y-tube olfactometer, we determined G. ashmeadi’s preference for volatiles of infested versus uninfested lemon, grapevine, red-tip photinia, and crape myrtle plants. The parasitoid’s first choice to, its residence time, and the number of visits per Y-tube arm were used to assess its plant choice. G. ashmeadi chose the infested lemon, red-tip photinia, or grapevine plant significantly more often (62%, 67%, and 63%, respectively) than uninfested hosts, whereas they chose infested and uninfested crape myrtle equally often (49%). Females spent more time in and made more visits to the olfactometer arm connected to the infested plant than to the arm connected to the uninfested plant, except when testing crape myrtle. When testing for a systemic plant response to GWSS infestation, only infested lemon was significantly more attractive to the parasitoids than was an uninfested plant. These results suggest that G. ashmeadi females use chemical volatiles as cues to find GWSS egg masses and that host finding success varies among GWSS host plants. Some plants used by GWSS as oviposition hosts may serve as an escape from parasitization by G. ashmeadi and act as reservoirs for new GWSS individuals. [Copyright &y& Elsevier]

Pierce's disease and almond leaf scorch disease have been chronic problems for California grape and almond growers, respectively. Both diseases are caused by the xylem-limited, bacterial pathogen Xylella fastidiosa, which is transmitted by xylem-feeding insects. We evaluated the potential for alfalfa to serve as a source of vectors and inocula in California. Analysis of Geographic Information Systems maps on the distribution and abundance of grape, almond, and alfalfa plantings determined that 94,521 ha of almond and grape were planted within 1.6 km of an alfalfa field. Seasonal trends of X. fastidiosa detection were monitored outdoors and in the greenhouse in five needle-inoculated alfalfa cultivars (CUF101, Moapa69, WL342, WL530HQ, and WL625HQ) over 2 years. Results suggest that cool winter temperatures reduced X. fastidiosa populations to undetectable levels but did not eliminate infections. Sampling of alfalfa fields to assess incidence of X. fastidiosa corroborated this result, with positive samples detected in summer only. Incidence of X. fastidiosa in alfalfa during summer was low, with only 6 positive samples out of 1,156 samples collected over 3 years. Insect trapping in alfalfa fields over 3 years found that the green sharpshooter (Draeculacephala minerva) was the most abundant vector. Within alfalfa fields, green sharpshooter abundance was highest in weedy areas, suggesting a preference for weeds over alfalfa. These results confirm that weedy alfalfa fields can serve as an important source of vectors. Incidence of X. fastidiosa in alfalfa was low, possibly due to preference of vectors for weeds over alfalfa. [ABSTRACT FROM AUTHOR]

Cover crops and reduced tillage are two elements of conservation agriculture with potential to support larger and more diverse soil biological communities. Soil macrofauna can be indicators of soil quality and can regulate multiple soil functions, but their response to cover crop adoption in temperate regions is not well studied. We evaluated soil macrofauna communities and related soil quality metrics in response to a 16-year winter cover crop and tillage trial located in the San Joaquin Valley of California, USA. The most abundant taxa were Coleoptera (beetles) and Lumbricidae (earthworms), with average densities ranging between 5 and 318 beetles m−2 and 65–480 earthworms m−2 depending on sample date and treatments. Overall macrofauna abundance increased by 93% with the addition of cover crops in rotation, and 50% with the elimination of tillage. Taxonomic richness increased by 48% with cover crops in treatments managed without tillage, though there was no effect of cover crops under standard tillage. Macrofauna abundance was positively related to total soil carbon, water infiltration, and soil aggregate stability. Macrofauna community composition was best explained by soil carbon, water stable aggregate fraction, and cover crop usage. Agricultural management practices that foster soil biological communities may support biodiversity and improve environmental outcomes critical for sustainable food production. • Soil macrofauna were evaluated after 16-yr of cover crop and tillage treatments. • Total macrofauna abundance increased by 93% with cover crops and 50% with no-till. • Macrofauna species richness was highest with the combination of cover crops and no-till. • Macrofauna abundance was positively related to several soil quality metrics. [ABSTRACT FROM AUTHOR]