Search

Microplastics (MPs) and nanoplastics (NPs) are pervasive environmental pollutants that are commonly ingested by organisms at different trophic levels. While the effects of MPs on aquatic organisms have been extensively studied, the impacts of MP ingestion on the host fitness of terrestrial organisms, mainly insects, have been relatively unexplored. This study investigates the effects of MP and NP ingestion on the survivorship and reproduction of 2 medically important mosquito species, Aedes aegypti Linnaeus (Diptera: Culicidae) and Aedes albopictus Skuse (Diptera: Culicidae). Larval and pupal survivorship of Ae. albopictus were not significantly affected by particle size or concentration, but there was a reduction of Ae. aegypti pupal survivorship associated with the ingestion of 0.03 µm NPs. In addition, there was little observed impact of 0.03 µm NP and 1.0 µm MP ingestion on adult survivorship, fecundity, and longevity. To further investigate the effects of MP ingestion on mosquito fitness, we also examined the effects of MPs of varying shape, size, and plastic polymer type on Ae. aegypti immature and adult survivorship. The data suggest that the polymer type and shape did not impact Ae. aegypti immature or adult survivorship. These findings highlight that understanding the effects of microplastic ingestion by mosquitoes may be complicated by the size, composition, and amount ingested. [ABSTRACT FROM AUTHOR]

The western tarnished plant bug, Lygus hesperus (Knight), has emerged as a pest of potatoes (Solanum tuberosum L.) in the Lower Columbia Basin of Oregon and Washington. This species is generally found infesting several other field-grown crops in the region; however, their host preference is poorly understood. Thus, greenhouse cage experiments were conducted to evaluate L. hesperus host preference by simultaneously presenting adults with 4 host plants: potato, alfalfa, Medicago sativa L., carrot, Daucus carota L., and pea, Pisum sativum L. In addition, an oviposition test was conducted.The results indicated that L. hesperus actively chose as a host and as an oviposition substrate among the 4 host plants. We found a significantly higher number of adults on alfalfa and potato plants over carrot or pea plants at 6 h, 24 h, and 48 h after adults were released into the cage. However, 96 h after release, more L. hesperus were found in alfalfa. In addition, female L. hesperus strongly preferred potato and alfalfa plants as an oviposition substrate over carrot and pea plants at 96 h after release. [ABSTRACT FROM AUTHOR]

Chironomid nonbiting midges are common in many waterbodies, occurring at high densities in sediment and also when flying adults emerge. Although important for food webs and ecosystem processes, the mass emergences of chironomid adults make some species nuisance pests. As part of an effort to develop "push–pull" strategies for managing midge populations, we investigated the importance of visual and chemical cues used by gravid females when selecting sites for oviposition. Field and laboratory oviposition choice tests with Chironomus riparius (Meigen) were used to assess the attractiveness of dark container colors and polarized light for females seeking water for egg laying. Females were not sensitive to increased intensity of polarized light, but they laid fewer eggs in containers with white color above the water's edge but black below the surface. A disruptive pattern of vertical black and white stripes at the water's edge reduced egg laying to a similar degree as white. To investigate the importance of olfactory or gustatory cues in oviposition decisions, we tested 3 potential chemical repellents (damaged larvae simulating predator presence, azadiractin, and picaridin) and 5 potential attractants (a tannin–molasses mixture, leaf detritus, live Hydrilla plants, periphyton, and fermented alfalfa infusions used to bait mosquito oviposition traps). Chemical cues appeared to play a weak role, if any, in oviposition choices. Onlyazadiractin (0.02 and 0.11 ppm) reduced the number of egg ropes deposited, but the mechanism may have been from mechanical trapping and drowning, not deterrence. [ABSTRACT FROM AUTHOR]

For the invasive planthopper Lycorma delicatula , eggs are an attractive target for surveys and management because they can persist from September through May before hatching, and remnants may be retained for years after hatching. Efforts to control this invasive species, though, are hampered by imperfect detection, which impedes early detection and rapid response, obscures management impacts, and reduces the fraction of egg masses that can be managed. To estimate egg mass detectability, we conducted 75 duplicate surveys of 20 × 5 m plots located in forest edges and disturbed areas frequently used by L. delicatula. We fit binomial mixture models and investigated the effects of weather, height (above or below 3 m), season (winter or spring), and basal area of trees within plots, finding no evidence that these factors affected detection rate, which averaged 52.2%. We additionally estimated the fraction of L. delicatula eggs that were laid above 3 m, putting them outside of easy reach for management by scraping or targeted ovicide application. This proportion varied with basal area of trees within plots, and the estimated mean was greater than 50% across the range of basal areas in study plots. Finally, we found that counts of old egg masses correlated with counts of new egg masses laid the year prior, but the ability to infer prior years' egg mass counts was limited. Together, these findings inform managers delimiting L. delicatula populations in mixed habitats and those treating egg masses to slow population growth and spread of this pest. [ABSTRACT FROM AUTHOR]

The US state of Georgia includes the range of several periodical cicada broods and is the southernmost state in which Brood X periodical cicadas emerge; however, no research has focused on this brood in this state. We used reports of sightings on social media, communication with the public, and our own searches to determine the geographic range in Georgia and timing of biological events. Both adults and exuviae were identified to species to determine the species makeup at those locations. The first Brood X adult was photographed on April 26 in Lumpkin County, and Magicicada septendecim L. was the most common species. Online records and site visits led to distribution records in nine counties, including six that provided no records in the 2004 emergence. Driving surveys revealed patchy distributions of chorusing adults and species distribution modeling further predicted locations where Brood X can be found in future surveys. We observed cicada oviposition scars at two locations and found no effect of host plant on presence or density of scars. Lastly, collections of dead adults showed female remains were less common and more likely to be dismembered. Further investigations of the periodical cicadas in Georgia are recommended to better understand the phenology, evolution, and ecology of these remarkable insects. [ABSTRACT FROM AUTHOR]

Larvae of two species of click beetle, Agriotes obscurus and Agriotes lineatus, are important pests of vegetable and field crops in both Europe and North America. Both species have been long and extensively studied, but to date little is known regarding the maturation and egg development of female beetles relative to their swarming periods. This knowledge is important for developing wireworm management tactics that target female beetles, as these would ideally eliminate the beetles before they oviposit. This paper is an attempt to address this knowledge gap. We dissected 2,450 female A. obscurus and 477 female A. lineatus collected in southwestern British Columbia in 2015-2020, and describe how their abdominal lipid content and number of mature eggs change during their swarming period. Based on the presence of mature and immature eggs, active ovarioles, and lipid content, we propose 6 consecutive beetle maturity stages. Beetles collected early in the season have high lipid content and no eggs. Over time, immature, then mature eggs appear and the lipid content decreases dramatically. Ovarioles are generally active throughout the swarming period, even when lipids are no longer present, suggesting that for these species egg laying may continue until the end of the season, and that fecundity depends both on a beetle's original lipid content at emergence, and subsequent diet., (© His Majesty the King in Right of Canada 2024. Reproduced with the permission of the Minister of Natural Resources Canada.)

Interspecific competition is an important ecological concept which can play a major role in insect population dynamics. In the southeastern United States, a complex of stink bugs (Hemiptera: Pentatomidae), primarily the brown stink bug, Euschistus servus (Say), and corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), are the 2 most common pests of field corn, Zea mays L. (Poales: Poaceae). Stink bugs have the greatest potential for economic injury during the late stages of vegetative corn development when feeding can result in deformed or "banana-shaped" ears and reduced grain yield. Corn earworm moths lay eggs on corn silks during the first stages of reproductive development. A 2-year field study was conducted to determine the impact of feeding by the brown stink bug during late-vegetative stages on subsequent corn earworm oviposition, larval infestations, and grain yield. Brown stink bug feeding prior to tasseling caused deformed ears and reduced overall grain yield by up to 92%. Across all trials, varying levels of brown stink bug density and injury reduced the number of corn earworm larvae by 29-100% and larval feeding by 46-85%. Averaged across brown stink bug densities, later planted corn experienced a 9-fold increase in number of corn earworm larvae. This is the first study demonstrating a competitive interaction between these major pests in a field corn setting, and these results have potential implications for insect resistance management., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The study of insect reproductive ecology is essential to determine species distributions and fate under changing environments. Species adapted to harsh environments are good examples to investigate the reproductive mechanisms that allow them to cope with the challenging conditions. We here focus on studying for the first time the reproductive ecology of a cold-adapted Drosophila obscura (Diptera: Drosophilidae) strain collected in Finland (subarctic climate region). We tested several reproductive traits such as fertility and fecundity to observe the onset of reproduction and gauge when sexual maturity is reached in both males and females. We combined these measures with an analysis of changes of their reproductive organs shortly after eclosion. We found that males matured several days before females and that this process was underpinned by female egg maturation and male accessory gland growth, while sperm was already present in two-day old males. This delayed maturation is not observed to the same extent in other closely related species and might be a signature of exposure to harsh environments. Whether this delay is an adaptation to cope with variation in resource availability or prolonged unfavorable temperatures is though not clear. Finally, our study adds to the set of reproductive mechanisms used by cold adapted species and the information presented here contributes to understanding the breadth of Drosophila reproductive ecology. [ABSTRACT FROM AUTHOR]

Parasitoid foraging behavior is affected by habitat and host plant differences. Egg parasitoids also use a combination of oviposition-induced and host-derived cues to find host eggs. This study compared parasitism by Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) on two squash bug species, Anasa tristis (DeGeer) and Anasa armigera Say (Hemiptera: Coreidae), by placing sentinel squash and cucumber plants with egg masses of either of the two squash bug species in squash and cucumber fields in a 3-way factorial design. Host density of wild A. tristis egg masses in squash fields may have influenced parasitoid foraging behavior on sentinel plants. In the 3-way factorial design, parasitism was higher on sentinel squash plants and in squash fields overall. However, parasitism on A. armigera egg masses was highest on sentinel cucumber plants in squash fields and parasitism on A. tristis egg masses was higher on sentinel squash plants in either squash or cucumber fields and lowest on sentinel cucumber plants in cucumber fields. Results suggest that parasitoids were able to specifically orient to the combination of host plant and host cues associated with A. tristis egg masses on sentinel squash plants, but that they were more responsive to plant-induced cues associated with cucumber when searching for A. armigera egg masses. Parasitoids appear to utilize different combinations of host plant and host cues when searching for eggs of the two squash bug species. [ABSTRACT FROM AUTHOR]

Drosophila suzukii (Matsumura), spotted-wing drosophila, is a major pest in small fruit crops including highbush blueberry. Controlling D. suzukii is challenging and chemical control is the main method to manage D. suzukii populations. Growers have expressed interest in using micro-sprinklers as an alternative method to apply insecticides. The current study aimed to evaluate if insecticide applications using micro-sprinklers can be used as an alternative method to protect the fruit from D. suzukii egg-laying. Modeling was used as an additional tool to parameterize the relative insecticide efficacy on oviposition. Field measurements of different treatments were conducted over periods of eleven days on commercial-standard highbush blueberry. Cyantraniliprole and spinetoram were applied using both a micro-sprinkler and a backpack sprayer. Treatments of Chromobacterium subtsugae and zeta-cypermethrin were only applied using a backpack sprayer. Both cyantraniliprole and spinetoram treatments resulted in moderate suppression of D. suzukii egg-laying. No statistical significance was found between micro-sprinkler and backpack sprayer applications for these two insecticides. Zeta-cypermethrin treatments using a backpack sprayer resulted in the most significant suppression of D. suzukii egg-laying over eleven days, while C. subtsugae was less effective at preventing D. suzukii egg-laying. Modeling simulations estimate the impact of the control methods on D. suzukii populations dynamics and simulation outputs indicated that backpack sprayers reduced D. suzukii populations at more pronounced levels compared to micro-sprinkler applications. The present study indicates that there is an underlying value of micro-sprinkler systems as an alternative and rapid spray application technique to help suppress D. suzukii pest populations during high-pressure periods in highbush blueberry production. [ABSTRACT FROM AUTHOR]

Polyphagous insects are characterized by a broad diet comprising plant species from different taxonomic groups. Within these insects, migratory species are of particular interest, given that they encounter unpredictable environments, with abrupt spatial and temporal changes in plant availability and density. Aster leafhoppers (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) arrive in the Canadian Prairies in spring and early summer and are the main vector of a prokaryotic plant pathogen known as Aster Yellows Phytoplasma (AYp) (Candidatus Phytoplasma asteris). Host choice selection behavior of Aster leafhoppers was evaluated through two-choice bioassays, using domesticated and wild plants species commonly found in the Canadian Prairies. Leaf tissues from these plants were collected and stained to quantify the number of stylet sheaths and eggs. To assess possible effects due to insect infection, two-choice bioassays were repeated using leafhoppers infected with AYp and a subset of plant species. When two domesticated or wild plant species were presented together, similar numbers of uninfected Aster leafhoppers were observed on both plant species in most combinations. In domesticated–wild plant bioassays, uninfected Aster leafhoppers preferred to settle on the domesticated species. There was little to no association between settling preferences and stylet sheath and egg counts. These findings provide a better understanding of AY epidemiology and suggest that after domesticated species germination, leafhoppers could move from nearby wild plants into the preferred cereals (Poales: Poaceae) to settle on them, influencing the risk of AYp infection in some of these species. [ABSTRACT FROM AUTHOR]

We investigated the effects of various foods and different rearing temperatures on the survival and development of the redlegged ham beetle Necrobia rufipes (De Geer) (Coleoptera: Cleridae), a serious pest of dry-cured hams. The diets tested were dried pet food, finely shredded copra, shredded cheese, dry-cured ham, ground fish meal, and mature larvae of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). As indicated by the growth index and k- values, N. rufipes populations grew fastest on the pet food and slowest on the copra. On the other hand, N. rufipes fed both ham and T. castaneum larvae produced significantly heavier larvae. The adult beetles lived significantly longer on cheese compared to other foods. Studies conducted to determine the developmental rates of N. rufipes fed pet food at temperatures of 22, 25, 28, and 31°C showed that the total developmental time and longevity of N. rufipes significantly varied at different temperatures tested. The shortest developmental time (93.32 d) was observed at 28°C. Oviposition rate was highest for females reared at 25°C while lowest at 22°C. Based on the development, reproduction, and thermal requirements, the most suitable temperature for N. rufipes was between 28 and 31°C. The results also revealed that larval cannibalism prevailed among adult beetles. [ABSTRACT FROM AUTHOR]

In insect–plant biology, oviposition choices and larval development on different host plants are crucial factors to be investigated.To design conservation strategies for protected Lepidoptera, which are overall oligophagous but locally monophagous, it is important to understand which host plant species is locally preferred. We thus investigated oviposition choices and larval development of the protected butterfly Zerynthia polyxena in controlled laboratory conditions, using three possible host plant species which are present in the Piedmont region: Aristolochia pallida, A. clematitis, and A. rotunda. We found that laboratory conditions are not favorable for Z. polyxena oviposition, even if the fertility of the females was in normal range for Papilionidae. However, we were able to understand the local monophagy of the species on A. pallida in the Susa Valley through larval survival and development stages. Egg hatching was similar among the three host plant species; however, even if larvae eat and grow similarly on the different host plant species until the third larval stage, the only larvae that reached the pupal stage were those fed with A. pallida. In conclusion, whereas Z. polyxena is oligophagous in the rest of Europe for the genus Aristolochia, the species is locally monophagous on A. pallida in the Susa Valley. [ABSTRACT FROM AUTHOR]

The evolution of oviposition preference in insects is considered a key evolutionary strategy in the context of host-plant interaction. It is hypothesized that insects maximize the survival and fitness of the subsequent generations by preferring specific host plant(s), known as the "preference-performance hypothesis." In this study, we tested whether adult host preference reflects the immature performance in an oligophagous insect, Phthorimaea absoluta Meyrick, a rapidly emerging invasive pest in Asia, Africa, and Europe. Based on a preliminary survey of the potential host plants of P. absoluta, we selected 6 Solanaceae species, namely, tomato, potato, eggplant, black nightshade, sweet pepper, and tobacco, for the oviposition preference studies. The results indicated that the tomato was the most preferred host in no-, dual- and multiple-choice assays, followed by potato, eggplant, and black nightshade. Subsequently, the insect life-table parameters were found to be superior on tomato compared to other hosts. The order of oviposition preference on the host plants was strongly correlated with the life-table parameters of P. absoluta. Thus, we provide clear evidence for the preference-performance hypothesis in the host selection behavior of P. absoluta. We also emphasize the necessity of conducting oviposition behavior research at various geographic locations to develop tailor-made integrated pest management programs., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Helicoverpa zea (Boddie) is a polyphagous pest that can cause serious damage to crops, including soybeans (Glycine max L.). In soybeans with both determinate and indeterminate growth habits, H. zea larvae are more commonly found on leaves compared to blooms, stems, and pods. Past research demonstrated that H. zea adults tend to oviposit near the upper part of the plant canopy in soybeans with a determinate growth habit. However, ovipositional selection on soybeans with an indeterminate growth habit is unknown. We hypothesized that H. zea would oviposit more uniformly throughout the canopy on indeterminate soybean growth habits due to more diffuse reproductive tissue. We planted field and greenhouse experiments with varieties sharing a similar relative maturity (2 maturity group [MG] 5.2 varieties and 2 MG 5.4/5.5 varieties) but with different growth habits. To test oviposition selection, adult H. zea females were allowed to oviposit under field and caged conditions. We counted the number of H. zea eggs and neonates on each plant tissue type from each of 3 equal parts in the plant canopy: upper, middle, and lower. In both experiments, eggs and neonates were most common on leaves at the top of the plant regardless of soybean growth habit. Consequently, ovipositional selection is likely independent of reproductive tissue availability, and patterns of oviposition through the canopy are similar in growth habits. An improved understanding of H. zea ecology in soybeans relative to indeterminate growth habits may improve recommendations for managing this significant pest of soybean., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

The ecological theory on host plant choice by herbivores suggests that mothers should choose plants that will maximize their offspring's success. In annual host plants, physiology (and therefore host suitability) is sometimes influenced by maturity and growth stage, which may influence female choice. Potato plants were grown under greenhouse conditions and used in choice and no-choice bioassays to determine the effect of plant maturity and variety on oviposition and number of stylet sheaths (which approximate stylet insertions) by tomato/potato psyllids. No-choice bioassays suggested that maturity (time since planting) did not influence oviposition behavior, but oviposition varied significantly among potato plant varieties. There was a significant effect of both maturity and variety on the number of stylet sheaths, which peak toward the middle of the growing season. We also examined tomato/potato psyllid responses to plants grown in a commercial field and again found no effect on oviposition but differences in stylet sheaths. The results suggest that differential susceptibility to zebra chip disease may be associated with unequal feeding rates. Future studies should examine whether the maturity of plants influences larval fitness. Finally, potato variety has an influence on both oviposition and "probing," and has implications for management strategies and the development of resistant potato varieties.

Generalist insect herbivores may be recorded from a great variety of host plants. Under natural conditions, however, they are almost invariably associated with a few primary host species on which most of the juveniles develop. We experimentally investigated the interaction of the generalist moth Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae) with four of its native host plants, two designated primary hosts and two secondary hosts (based on field observations). We tested whether primary host plants support higher survival rates of larvae and whether they are more attractive to ovipositing moths and feeding larvae. We also evaluated whether relative attractiveness of host plants for oviposition matches larval survival rates on them—the preference-performance hypothesis. Moths laid significantly more eggs on two of the four host plant species, one of them a primary host, the other a secondary host. Larvae developed best when reared on the attractive secondary host, developed at intermediate levels on the two primary hosts, and performed worst on the less attractive secondary host. Relative attractiveness of the four host plants to caterpillars differed from that of the moths. Neither adult nor larval attraction to host plants fully supported the preference-performance hypothesis, but oviposition was better correlated with larval survival rates than was larval attraction. Our results suggest the relative frequency at which particular host species are used in the field may depend on factors not yet considered including the long-distance attractants used by moths and the relative distribution of host species. [ABSTRACT FROM AUTHOR]

The western tree hole mosquito, Aedes sierrensis (Ludlow) (Diptera: Clucidae), is a pestiferous mosquito with a range extending over the entire pacific seaboard and into portions of the intermountain west. As a peridomestic heartworm vector, it demands at least some level of surveillance to understand its abundance. However, the species is refractory to a majority of conventional vector surveillance approaches for tracking mosquitoes. To find more options for Aedes sierrensis surveillance, a variety of oviposition attractants were evaluated in arena-style choice assays using colony reared adults. A range of infusion treatments (e.g., alfalfa, oak, and beetroot) were examined and then combined with investigations of liquid color as well as ovicup color and entryway position. These studies revealed that Ae. sierrensis have an affinity for purple coloration, plain water, and larger entryway sizes for oviposition cups. A prototype ovicup was 3D-printed using purple filament and multiple types of entryways, and used to re-test infusion waters. No particular attraction differences were detected after normalizing for purple color. Comparisons to black 3D-printed cups yielded surprising observations that male mosquitoes also aggregated on purple cups while females sheltered, but not necessarily oviposited, in black cups. Although this was only a laboratory-based assessment, these studies provide useful information for future field trials of potential oviposition traps for surveillance of Ae. sierrensis., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Monophagous insects that use discrete resources for oviposition and feeding are especially sensitive to variations in host quality and availability because their opportunities to find these resources are scarce. The monophagous tephritid fly Anastrepha spatulata Stone is a tephritid fly that uses as hosts the fruits of the non-economically important Schoepfia schreberi J. F. Gmel. Scant information of host utilization behavior in the field is available for this species. Wild individually marked flies were observed during the fruiting season. Observations of oviposition, feeding and resting on three trees were taken hourly from 0900 to 1800 hours on days with benign weather. Our results suggest that females can use fruits for oviposition or for feeding according to a temporal scale. Females were significantly more likely to feed on smaller hosts and oviposit in larger ones. Additionally, individual variation in host patch exploitation was detected. However, females that fed on a natural food source such as host fruit juice oviposited fewer eggs than females provided an artificial diet of sucrose and hydrolyzed yeast. Results indicate that females use different foraging tactics during the fruiting season and confirm that, in this case, the host plant is not the center of activity. [ABSTRACT FROM AUTHOR]

Eucryptorrhynchus brandti is a trunk-boring pest that causes severe damage to its single host, Ailanthus altissima in China. Eucryptorrhynchus brandti adults require supplementary nutrition to achieve sexual maturity. Adults feed on petioles, shoots, 2- to 3-yr-old branches, and stems of A. altissima , but prefer to feed on stems. The effects of different host plant tissues on ovary development and oviposition in E. brandti are unclear. Thus, we examined the effects of the consumption of A. altissima petioles, shoots, branches, and stems on ovary development of E. brandti. Using ovaries of different ages, we also evaluated the differentiation of ovarioles, presence and appearance of follicular relics, number of eggs, cuticle hardness, and fat body quantity over time. We found the reproductive system was composed of two ovaries, lateral oviducts, a common oviduct, and spermatheca. The physiological age of ovaries was divided into three nulliparous and three parous stages. Females fed on stems had mature ovaries and successfully oviposited; females fed on other tree tissues or water had no functional ovaries and did not lay eggs. We found virgin females must obtain sufficient nutrition, as evidenced by the immature ovaries in females fed the water. We also found that only stems of A. altissima contribute to egg development; however, the other tree tissues do not contribute to egg development. These findings improve our understanding of the feeding preference of E. brandti from the perspective of ovary development as well as optimal host tissues for ovary development. [ABSTRACT FROM AUTHOR]

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most economically important pest insects of fruit crops worldwide. Mediterranean fruit fly can cause up to 100% crop loss in susceptible fruit. In order to formulate best management practices, it is critical to understand how Mediterranean fruit fly overwinters in a given geographical location and bridge the gap between autumn and spring populations. In this study, we evaluated the overwintering potential of Mediterranean fruit fly immature and adult stages in two locations in Perth Hills, Western Australia. We also monitored wild adult Mediterranean fruit fly populations for 2 yr. Adults were present year-round with captures very low in winter to early spring relative to summer and autumn. Field experiments revealed that immature stages in apples (eggs/first instar) and soil (pupae) remained viable in winter, emerging as adults at the onset of warmer weather in spring. In field cages, adults survived 72–110 d, and female laid viable eggs when offered citrus fruit, though only 1–6% eggs survived to emerge as adults. Adults survived longer in field cages when offered live citrus branch. The findings suggest that all Mediterranean fruit fly life stages can survive through mild winter, and surviving adults, eggs in the fruit and/or pupae in the soil are the sources of new population that affect the deciduous fruit crops in Perth. We recommend that Mediterranean fruit fly monitoring is required year-round and control strategies be deployed in spring. Furthermore, we recommend removal of fallen fruit particularly apple and other winter fruit such as citrus. [ABSTRACT FROM AUTHOR]

The article focuses on monarch butterfly (Danaus plexippus L.), whose eastern North American population has decreased approximately 80%. Topics discussed include loss of common milkweed (Asclepias syriaca L.) from agricultural landscapes in the north central United States due to the adoption of herbicide-tolerant row crops, egg predation rates, and safe habitats for monarch reproduction.

The genus Monochamus Dejean (Coleoptera: Cerambycidae) includes large, woodboring, longhorned beetles, which colonize pine trees in North America. Many authors have classified the genus as saprophagous, but one recent study reported successful colonization of standing jack pine trees (Pinus banksiana Lamb.) (Pinales: Pinaceae) following severe wind disturbance in Minnesota. We tested whether two Monochamus species native to the southeastern United States (M. titillator (Fabricius) and M. carolinensis (Olivier)) could successfully colonize healthy shortleaf pines (Pinus echinata Mill.) (Pinales: Pinaceae) in recently harvested stands without coincident abiotic or biotic stressors, such as lightning strikes or bark beetle attacks. We attached commercially available semiochemical lures, including monochamol, ethanol, and ipsenol, to healthy shortleaf pine trees and observed Monochamus spp. oviposition response. Egg development was monitored following oviposition by harvesting attacked trees and dissecting oviposition pits. High numbers of oviposition pits were observed on trees treated with lures containing the bark beetle pheromone ipsenol and pits were highly concentrated on the tree bole near lures. Although egg deposition occurred, pit dissection revealed large amounts of resin present in almost all dissected pits and that egg hatch and subsequent larval development were rare. Our results demonstrate that southeastern Monochamus spp. are unlikely to be primary pests of healthy shortleaf pines due to resinosis. To better understand the host finding behavior of these two Monochamus species, we also conducted trapping trials with several semiochemical combinations. Both species and sexes demonstrated similar attraction to compounds, and the most attractive lure combined host volatiles, pheromone, and sympatric insect kairomone. [ABSTRACT FROM AUTHOR]

Larvae of many insect species, including stag beetles, have a limited mobility from their initial oviposition site. The fate of immature stages, therefore, depends on the maternal choice of oviposition site. Decaying wood preference by stag beetles was studied in a dry-evergreen forest in Chanthaburi province, Thailand. From a total of 270 examined logs, 52 contained stag beetles (255 total), which were identified to eight species from five genera. Aegus chelifer chelifer MacLeay, 1819 (Coleoptera: Lucanidae) was the dominant species both by occurrence and by number of individuals. The occurrence and numbers of stag beetle larvae found in logs was more frequent in those of a moderate decay class, which had moderate hardness and water content. Principal component analysis (PCA) revealed that logs with stag beetles had relatively high nitrogen content and fungal biomass. Thus, selection of oviposition sites by stag beetles was likely to depend on both the log decay stage (or hardness) to protect immature stages from natural enemies and its nutritional properties to enhance the larval performance. [ABSTRACT FROM AUTHOR]

The navel orangeworm Amyelois transitella (Walker, 1863, Lepidoptera: Pyralidae), a pest of California tree nuts, is associated with the fungus Aspergillus flavus, and previous research suggests these species are facultative mutualists. Because navel orangeworm larvae exhibit improved performance on diets containing this fungus, orientation toward hostplants infected with A. flavus may be adaptive. We conducted behavioral assays to determine if larvae respond to chemical cues produced by almond hull split and fungal infection. In petri dish arenas, larvae showed a preference for 1-octen-3-ol and 2-phenylethanol, volatiles characteristic of damaged plants, as well as methanolic extracts of almond meal with 1-octen-3-ol and the fungal volatile conophthorin. In contrast, larvae displayed aversion to ethyl benzoate, an inhibitor of fungal growth. When we assessed oviposition behavior relative to substrates with and without A. flavus, females laid almost twice as many eggs near inoculated surfaces. Moreover, an average of 63% of eggs laid near inoculated substrates were fertilized, compared with 24% of eggs near uninoculated sites. We also tested the hypothesis that unfertilized eggs are laid on nutrient-poor substrates to provide supplemental nutrition for larvae in an assay comparing larval survivorship in the presence and absence of unfertilized eggs. Neonates given eggs survived 2.5 times longer on an average than unprovisioned neonates (208.8 h vs. 85.2 h), indicating that this species may compensate with cannibalism for oviposition on lower-quality food sources. We conclude that larvae orient to probable host plant and fungal volatiles associated with hull split and document a possible strategy for larvae to establish on low-quality hosts. [ABSTRACT FROM AUTHOR]

Parasitoid fitness depends on its ability to manipulate reproductive strategies when in competition. This study investigated the parasitism and sex allocation strategies of the parasitic wasp Diaeretiella rapae McIntosh at a range of host (Brevicoryne brassicae L.) and conspecific densities. The results suggest that D. rapae females adjust their progeny production and progeny sex ratio with changing competition. When foraging alone, female D. rapae parasitize larger number of B. brassicae nymphs when the number of available hosts is increased, but the overall proportion of parasitized hosts decreases with increase in host density. The proportion of female offspring also decreases with elevated host density. Increase in the number of female D. rapae foraging together increased total parasitism, but reduced relative contribution of each individual female. The number of female progeny decreased when multiple females competed for the same host. However, foraging experience in the presence of one or more conspecifics increased the parasitism rate and proportion of female progeny. Competing females were more active during oviposition and had shorter lives. The study suggests that both host and foundress (female parasitoid) densities have significant effect on progeny production, sex allocation, and longevity of foraging females. [ABSTRACT FROM AUTHOR]

Cereal leaf beetle, Oulema melanopus L., is a pest of small grains and the literature conflicts on whether it is more abundant in sparse or dense stands of wheat. Our objectives were to determine the impact of stand denseness on cereal leaf beetle abundance and to investigate the regional dispersion of cereal leaf beetles across North Carolina and Virginia. One-hundred twenty fields were sampled across North Carolina and Virginia during 2011 for stand denseness, and cereal leaf beetle eggs, larvae, and adults. Two small-plot wheat experiments were planted in North Carolina using a low and a high seeding rate. Main plots were split, with one receiving a single nitrogen application and one receiving two. Egg density, but not larva or adult density, was positively correlated with stand denseness in the regional survey. Furthermore, regional spatial patterns of aggregation were noted for both stand denseness and egg number. In the small-plot experiments, seeding rate influenced stand denseness, but not nitrogen application. In one experiment, egg densities per unit area were higher in denser wheat, while in the other experiment, egg densities per tiller were lower in denser wheat. Larvae were not influenced by any factor. Overall, there were more cereal leaf beetle eggs in denser wheat stands. Previous observations that sparse stands of wheat are more prone to cereal leaf beetle infestation can be attributed to the fact that sparser stands have fewer tillers, which increases the cereal leaf beetle to tiller ratio compared with denser stands. [ABSTRACT FROM AUTHOR]

Glycobius speciosus (Say) was studied in New York State to elucidate poorly known aspects of its biology. Head capsule size from excavated larvae coupled with gallery lengths measured at the time of excavation was used to characterize larval development. Partial life tables indicated nearly 20% of G. speciosus survive to adulthood. Larvae experienced 30% of their mortality during early development, 27% during mid-larval development, and 43% during late larval development. Predation by hairy woodpeckers, Dryobates villosus (Linnaeus) (Piciformes: Picidae), the only unambiguous source of mortality, accounted for 43% mortality in naturally infested trees located and followed 2004-2009, and 74% late instar mortality. One parasitoid, Dolichomitus irritator (Fabricius) (Hymenoptera: Ichneumonidae), was recovered from a single larva. Beetles emerged between 316 accumulated DD (base 10 °C) and 648 DD. Males emerged prior to, or simultaneously with, females and lived longer. Female fecundity averaged 41.3 ± 6 eggs. Larval eclosion occurred 7-10 days after oviposition. Non-functional ovipositors observed in 16% of females represented an appreciable reproductive loss. In 77% of infested trees 1 oviposition site was located and in 70% of oviposition sites examined only 1 or 2 larvae successfully eclosed, penetrated the bark to the phloem-xylem interface, and began feeding. Beetles preferred southern and eastern aspects for oviposition which occurred preferentially on the lower bole (<20 cm). Male beetles had longer and wider antennae than females, pronotal pits containing gland pores, and a straight to concave posterior margin of the terminal sternite compared to the more rounded margin of females., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Oviposition in a generalist parasitoid is a complex process that involves interactions among its host, host plant, and spatiotemporal environment. Our study was aimed at exploring the ability of a generalist parasitic wasp, Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), in perceiving odor cues from its host insect [Oriental fruit fly Bactrocera dorsalis (Hendel, Diptera: Tephritidae)] in infested mango fruits. A series of experiments involving behavioral and electrophysiological studies suggest that D. longicaudata is able to distinguish host infested fruit volatiles from uninfested. Additionally, we found that D. longicaudata can distinguish between high and low-level infestations using specific cues emanating from fruits. Coupled gas chromatography-electroantennographic detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS) analysis of infested mango fruit head space volatiles identified compounds such as ethyl butanoate, ethyl 3-hydroxybutyrate, β-myrcene, trans-β-ocimene, allo-ocimene, ethyl octanoate, ethyl-α-toulate, β-elemene, β-caryophyllene, humulene, caryophyllene oxide, ethyl dodecanoate, ethyl hexadecanoate, 2-furancarboxylic acid, 3-hydroxy-2-methyl-4-pyrone, and phenethyl alcohol emanated from three different host treatments with different levels of larval infestation which elicited antennal responses in D. longicaudata. We suggest that these cues might play a significant role in attracting D. longicaudata in the field., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Conogethes punctiferalis is a serious pest in China affecting a wide variety of field crops, fruits, and forest trees. Many insects require supplemental nutrients after emergence to compensate for insufficient nutrients at the larval stage. In this study, to better understand the determinants of C. punctiferalis survival and reproduction, the impact of supplemental nutrition was examined. In particular, the effects of 11 treatments (5% sucrose, 10% sucrose, 15% sucrose, 5% sophora honey, 10% sophora honey, 15% sophora honey, 5% wild honey, 10% wild honey, 15% wild honey, distilled water, and blank control) on adult longevity and oviposition were evaluated, with detailed morphological analyses of ovarian development in the 10% sucrose, distilled water, and blank control groups. Conogethes punctiferalis required supplementary nutrition after emergence. Supplementary nutrition improved fecundity (number of eggs laid) and longevity, and 10% sucrose water had the greatest effects. The preoviposition period and oviposition period of C. punctiferalis females were longer, and the numbers of eggs in female ovarian tubes and eggs laid by females were higher in the 10% sucrose water group than in other groups. Females supplemented with distilled water laid a small number of eggs. Without nutrient supplementation, females did not lay eggs. In conclusion, supplemental nutrition was beneficial for ovarian development in female moths, prolonging the oviposition period and lifespan, and was an important factor affecting population dynamics. These results lay a foundation for further analyses of the nutritional requirements for C. punctiferalis in the field and provide a reference for indoor population feeding., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Wood-feeding termites have a nitrogen-poor diet and have therefore evolved nitrogen conservation strategies. However, termite workers molt periodically, and throughout the lifetime of a colony, millions of exuviae, a nitrogen-rich resource, are produced by the colony. In Coptotermes Wasmann, workers foraging at remote feeding sites must return to the central part of the nest to molt, where the queen, king, eggs, and larvae are located. It was hypothesized that this molting-site fidelity is an efficient way to recycle nitrogen for reproduction and colony growth, as nestmates involved in exuviae consumption can directly transfer such resources to individuals engaged in reproduction (the queen) or growth (larvae). This study investigates whether incipient colonies of C. gestroi (Wasmann) can gain additional biomass when they are fed supplementary exuviae. Incipient colonies were reared in nitrogen-poor or nitrogen-rich conditions, and 0, 1, 5, or 10 exuviae were added to 3-month-old colonies. After 6.5 months, colonies reared in nitrogen-poor environments gained significantly more biomass when exuviae were added than colonies with no added exuviae. However, the addition of exuviae had no effect on colony growth for colonies reared in nitrogen-rich environments. In a second experiment, queens from colonies in which exuviae were effectively removed laid fewer eggs than queens from colonies in which exuviae were not removed. Therefore, consumption of exuviae from molting individuals by nestmates is an important part of the nitrogen recycling strategy in Coptotermes colonies, as it facilitates queen oviposition and colony growth, especially when such colonies have limited access to nitrogen-rich soils., (Published by Oxford University Press on behalf of Entomological Society of America 2023.)

Since 2003, growers of Florida watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] have periodically suffered large losses from a disease caused by Squash vein yellowing virus (SqVYV), which is transmitted by the whitefly Middle East-Asia Minor 1 (MEAM1), formerly Bemisia tabaci (Gennadius) biotype B. Common cucurbit weeds like balsam apple (Momordica charantia L.) and smellmelon [Cucumis melo var. dudaim (L.) Naud.] are natural hosts of SqVYV, and creeping cucumber (Melothria pendula L.) is an experimental host. Study objectives were to compare these weeds and 'Mickylee' watermelon as sources of inoculum for SqVYV via MEAM1 transmission, to determine weed susceptibility to SqVYV, and to evaluate whitefly settling and oviposition behaviors on infected vs. mock-inoculated (inoculated with buffer only) creeping cucumber leaves. We found that the lowest percentage of watermelon recipient plants was infected when balsam apple was used as a source of inoculum. Watermelon was more susceptible to infection than balsam apple or smellmelon. However, all weed species were equally susceptible to SqVYV when inoculated by whitefly. For the first 5 h after release, whiteflies had no preference to settle on infected vs. mock-inoculated creeping cucumber leaves. After 24 h, whiteflies preferred to settle on mock-inoculated leaves, and more eggs were laid on mock-inoculated creeping cucumber leaves than on SqVYV-infected leaves. The transmission experiments (source of inoculum and susceptibility) show these weed species as potential inoculum sources of the virus. The changing settling preference of whiteflies from infected to mock-inoculated plants could lead to rapid spread of virus in the agroecosystem. [ABSTRACT FROM AUTHOR]

Nepenthes pitcher plants are colonized by a variety of specialized arthropods. As Aedes mosquitoes are container breeders, Nepenthes pitchers are a potential candidate oviposition site for vector species, such as Aedes aegypti (L.) and Aedes albopictus (Skuse). However, Aedes spp. are not commonly encountered in Nepenthes pitchers, and the environment inside the pitchers of some species is lethal to them. One exception is Nepenthes ampullaria Jack, whose pitchers are known to be colonized by Ae. albopictus on very rare occasions. Given that Ae. albopictus larvae can survive in N. ampullaria pitcher fluids, we sought to determine why pitcher colonization is rare, testing the hypothesis that gravid Aedes mosquitoes are deterred from ovipositing into container habitats that have similar characteristics to N. ampullaria pitchers. Using plastic ovitraps of different sizes, colors, and with different types of fluids (based on the characteristics of N. ampullaria pitchers), we compared oviposition rates by Aedes mosquitoes in urban and rural areas within the geographical range of N. ampullaria near Kuala Lumpur, Malaysia. Ovitraps that were black and large (>250-ml capacity) accumulated significantly more eggs than ovitraps that were smaller, or green in color. In terms of size and color, small, green ovitraps are analogous to N. ampullaria pitchers, indicating that these pitchers are not particularly attractive to gravid Ae. albopictus. Although Aedes spp. are capable of colonizing N. ampullaria pitchers, the pitchers are relatively unattractive to gravid females and do not represent a significant habitat for larvae of dengue vectors at present. [ABSTRACT FROM AUTHOR]