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The Turkestan cockroach, Blatta lateralis (Walker), is a peridomestic pest of growing concern in the US Southwest. The parasitoid Aprostocetus hagenowii (Ratzburg) is used in IPM programs targeting other blattid cockroach species and may aid in B. lateralis suppression. Information about the ability of A. hagenowii to parasitize B. lateralis is lacking. A no-choice host-switching experiment was used to test A. hagenowii acceptance of B. lateralis oothecae, and a multigenerational no-choice experiment was used to determine the suitability of B. lateralis as a host for A. hagenowii over several months of rearing. Periplaneta americana (L.) (Blattodea: Blattidae), the preferred host of A. hagenowii, and Blatta orientalis L., a known host and relative of B. lateralis, were used for comparison. Development time was similar among hosts and generations (P > 0.05). Parasitism success and proportion of female progeny declined significantly with subsequent generations on both Blatta spp. (parasitism success: χ2 = 14.916; df = 2; P = 0.001; proportion female: H = 6.364; df = 2; P = 0.041). These results suggest that A. hagenowii may initially aid in suppression of B. lateralis, but an overall decline in fitness will require repeated releases or provisioning of P. americana oothecae. Development of a strain more suitable for B. lateralis control may be possible via selection from laboratory strains or through use of wild A. hagenowii from areas where B. lateralis is present.

Stink bugs (Hemiptera: Pentatomidae) are commonly monitored using pyramid traps baited with a pheromone. Initially, the pyramid traps were painted yellow and predominantly used to monitor native stink bug species. However, research studies involving the exotic Halyomorpha halys Stål (Hemiptera: Pentatomidae) now use pyramid traps that are black, not yellow. As H. halys moves across the southeastern United States, the use of a single trap, yellow or black, for monitoring and conducting research studies would be beneficial. Our objective was to compare black and yellow pyramid traps baited with a lure to determine if one was superior for trapping herbivorous stink bugs. This study was conducted at four locations, three in Alabama and one in Georgia, over 2 yr. Additionally, residual efficacy of the lure was measured via trap capture over 1-mo intervals. Our results showed that only when native stink bug species were combined, and only in 1 yr, were captures significantly affected by trap color. Capture of the exotic H. halys and the most abundant native species, Euschistus servus (Say), was not significantly affected by trap color. Trap capture was significantly affected by how long a lure was in a trap. The data from this study suggests that when traps are used in conjunction with a pheromone to monitor multiple species of adult stink bugs, especially native species, the yellow pyramid trap is favored.

In solitary endoparasitoids, oviposition in a host previously parasitized by a conspecific (superparasitism) leads to intraspecific competition, resulting in the elimination of all but one parasitoid offspring. Therefore, avoidance of parasitized hosts presents a strong selective advantage for such parasitoid species. Parasitoids use herbivore-induced plant volatiles (HIPVs) to find their hosts. In this study, we evaluated the ability of Microplitis croceipes (Hymenoptera: Braconidae) to discriminate between unparasitized and parasitized Heliothis virescens (Lepidoptera: Noctuidae) larvae using cotton plant odors as cues. A combination of behavioral and analytical techniques were used to test two hypotheses: (i) parasitoids will show preference for plant odors induced by unparasitized hosts over odors induced by parasitized hosts, and (ii) the parasitism status of herbivores affects HIPV emission in plants. Heliothis virescens larvae were parasitized for varying durations (0, 2 and 6-days after parasitism (DAP)). In four-choice olfactometer bioassays, female M. croceipes showed greater attraction to plant odors induced by unparasitized hosts compared to plant odors induced by parasitized hosts (2 and 6-DAP). Comparative gas chromatography-mass spectrometry analyses of cotton volatiles indicated reduced emission of 10 out of 21 identified compounds from plants infested by parasitized hosts compared with plants infested by unparasitized hosts. The results suggest that changes in plant volatile emission due to the parasitism status of infesting herbivores affect recruitment of parasitoids. Avoidance of superparasitism using plant odors optimizes host foraging in M. croceipes, and this strategy may be widespread in solitary parasitoid species.

Pseudacteon curvatus and P. obtusus are two species of parasitic phorid flies (Diptera: Phoridae), introduced in the southern USA for biological control of Solenopsis fire ants (Hymenoptera: Formicidae). The preference of both parasitoid species (P. curvatus and P. obtusus) for native Solenopsis fire ants (S. geminata complex) versus imported fire ants, S. saevissima complex (S. invicta and S. richteri) was investigated in four-choice olfactometer assays. We hypothesized that differences in the venom alkaloid profiles of fire ant species mediate host preference in phorid flies. In olfactometer bioassays, female P. obtusus showed preference for the venom alkaloid (cis + trans alkaloid mixture) of the imported S. invicta fire ant over the venom alkaloid of the native geminata fire ant. Similarly, P. obtusus showed preference for the venom alkaloid of the S. richteri fire ant over that of the native S. geminata ants. Pseudacteon curvatus also showed preference for the venom alkaloid of the S. invicta and S. richteri fire ants over that of the native geminata ants in separate bioassays. The results suggest that host preference in P. curvatus and P. obtusus is mediated, at least in part, by differences in the venom alkaloid profile of various fire ant species. This finding may explain why Pseudacteon species associated with either the S. geminata or S. saevissima complexes have not switched to the other group despite the overlap of native and imported fire ants in some areas of their distributions.

The kudzu bug, Megacopta cribraria (Fabricius) (Hemiptera: Plataspidae), is a major economic pest of soybean in the southeastern United States. With climate warming, this pest is expected to move northward and cause additional crop damage. Parasitoid biocontrol is a potential method of integrated pest management for kudzu bug. Two species of egg parasitoid wasps have been observed emerging from kudzu bug egg masses in the southeastern United States: Paratelenomus saccharalis (Dodd) (Hymenoptera: Platygastridae) and Ooencyrtus nezarae (Ishii) (Hymenoptera: Encyrtidae). This paper used egg mass emergence data collected between 2018 and 2020 in Alabama soybean fields and compared the data to weather indices. Indices included the number of days with minimum temperatures below zero, accumulated rainfall (mm m−2), as well as species specific metrics of accumulated growing degree days, accumulated daily minimum temperature (°C), and accumulated daily maximum temperature (°C). Emergence of the generalist parasitoid, O. nezarae, was highly correlated with kudzu bug nymph abundance, accumulated degree day, accumulated daily temperatures, and precipitation. Ooencyrtus nezarae emergence was predicted in a stepwise regression equation by aggregated degree day and date of collection, which indicates that seasonality may be a predictor of its presence. In contrast, collections of the specialist parasitoid, P. saccharalis, were near-zero throughout the collection period, suggesting that this species may no longer be a usable biocontrol agent in the southeastern United States as a result of external limiting factors.

The Simulium damnosum Theobald complex transmits Onchocerca volvulus Leuckart (Spirurida: Onchocercidae), the causative agent of onchocerciasis. Recent evidence suggests that control efforts have strongly suppressed parasite populations, but vector surveillance is needed in parts of Africa where the disease remains endemic. Here, studies on biting rates and infectivity status of suspected vector species were conducted in three onchocerciasis-endemic areas, namely Iwo, Ede, and Obokun, in Osun State, Nigeria. A total of 3,035 black flies were collected between October 2014 and September 2016, and examined for parity and parasites using standard methods. A separate collection of 2,000 black flies was pool-screened for infectivity using polymerase chain reaction (PCR) amplification of the O-150 marker. Results showed that parous flies were significantly less common than nulliparous flies with overall parous rates of 8.02% in Iwo and 35.38% in Ede at the end of the study period. Obokun had a parous rate of 22.22% obtained in the first year only. None of the dissected parous flies were infected with O. volvulus and PCR assays showed no amplification of O-150 O. volvulus-specific repeats in head and body pools. However, annual biting rates exceeded the World Health Organization threshold of 1,000 bites/person/yr. Thus it appears that, with such high rates of biting, even low levels of vector infection can sustain onchocerciasis in African communities.

Entomopathogenic nematodes (EPN) use odor cues to locate and infect their insect hosts in the soil, making them an important tool in sustainable management of agricultural insect pests. However, very little information is available on the role of soil bacteria in mediating belowground interactions between plants, herbivores and the EPN. In this study, a maize-herbivore-entomopathogenic nematode complex was used to investigate the effect of plant root colonization by a soil bacterium on belowground tritrophic interactions. The impact of maize root colonization by Bacillus pumilus strain INR-7 on the preference of the EPN, Heterorhabditis bacteriophora was tested in four arm olfactometer bioassays in the presence or absence of the root herbivore Diabrotica virgifera LeConte (Coleoptera: Chrysomelidae). Plant volatiles were collected for profile characterization. Further preference assays were performed using plant volatile extracts and synthetic volatiles. In the absence of the root herbivore, the nematodes were attracted to maize roots whose seeds were coated with dead and living bacteria. In the presence of the herbivore, the nematodes selectively oriented towards infested plants whose seeds were treated with B. pumilus strain INR-7 than dead bacteria treated, untreated plants or sunshine sand mix. In contrast, plant volatile extracts or pure compounds did not reproduce the observed behavior. The study showed that bacterial coating of maize seeds with the tested strain may play an important role in shaping belowground tritrophic interactions through mechanisms that would require further investigations. The potential of B. pumilus strain INR-7 integration in maize rootworm management program is discussed.

Carnivorous animals put selection pressure on their herbivorous preys, leading to the development of defensive traits in prey species and counter defensive traits in carnivores—an evolutionary arms race for survival. For instance, larvae of the moth Heliothis virescens use defensive oral secretions to deter attacking parasitic wasps (parasitoids). However, it is not clear whether parasitoids also use the same secretion for host location. If carnivores follow the herbivore model, evolution should favor specialist over generalist parasitoid species in their ability to manipulate host defensive chemicals. To test this prediction, Microplitis croceipes and Cotesia marginiventris, both larval endoparasitoids of H. virescens, were used as a study system. Microplitis croceipes is relatively specialized on Heliothis/Helicoverpa species while C. marginiventris is a generalist parasitoid on several noctuid host species. Innate behavioral responses of parasitoids to host defensive secretion were tested in Petri dish arena and Y-tube olfactometer bioassays. Heliothis virescens defensive secretion was manually applied to a spot in a sector (secretion zone) of the arena. Tracking data suggests that both parasitoid species are likely to locate the secretion spot once they enter the secretion zone. Comparing the two species, however, M. croceipes (specialist) spent significantly more time in the secretion zone and spot than C. marginiventris (generalist). In Y-tube olfactometer bioassays, the secretion elicited a strong attraction in M. croceipes but not in C. marginiventris, supporting our prediction. We discussed chemical-mediated counter defense in natural enemies of pest insects and the significance of the results to parasitoid-host coevolution.

We studied host discrimination in flight morph ofCallosobruchus maculatus(F.) among the legume plants Ife-brown (IB) and black-eyed (BE) cowpea,Vigna unguiculata(L. Walp), soybean (SB), andGlycine max(L.) and analysed legume volatiles towards developing an attractant forC. maculatus. Olfactometry studies were conducted to investigate attraction of mated 3–4-day-old femaleC. maculatusto legume plants with the green pod (PGP), green pods (GP), plant with the ripened pod (PRP), ripened pod (RP), and plant without pod (PWP). We also assessed the response of beetles to phenological stages of the most attractive legume. In Y-tube bioassays,C. maculatusshowed greater attraction to individual legumes at three phenological stages: PGP (73–93%), PRP (80–100%), and RP (63–93%) compared with PWP (6–36%). In four-choice bioassays,C. maculatuspreferred IB at all stages to other legumes. SB had an insignificant attraction on the beetle. The RP of IB was the most attractive part of the plant. Gas chromatography (GC) and GC–mass spectrometry (GC–MS) analyses of volatiles emitted by RP of the legumes revealed a variation in the compositions of odour blends. Benzaldehyde was found in the volatiles of IB and BE with a higher emission in IB. Octanone was detected only in IB. The two compounds were undetected in SB volatiles. These results reveal that in addition to infesting cowpea plants at RP stage as reported in previous studies,C. maculatuscould also infest cowpea plants at the GP stage.

The field cockroach, Blattella vaga Hebard (Blattodea: Ectobiidae), is native to central Asia including Afghanistan, India, Iran, Pakistan, and Sri Lanka. It was described first in 1935; however, from specimens collected in Arizona and California. Since then, the distribution of B. vaga has slowly increased along the southern United States and Mexican border, apparently following major interstate highways. We report the first record of B. vaga from Mobile, Alabama, and suggest that this species will spread to Florida and possibly northward into Georgia and South Carolina. The identification was confirmed using morphological, chemical, and molecular methods. We suggest that when possible, multiple independent methods should be used to confirm species identifications.

Some fire ants of the genus Solenopsis have become invasive species in the southern United States displacing native species by competition. Although the displacement pattern seems clear, the mechanisms underlying competitive advantage remain unclear. The ability of ant workers to produce relatively larger amount of alarm pheromone may correspond to relative greater fitness among sympatric fire ant species. Here we report on quantitative intra-specific (i.e. inter-caste) and inter-specific differences of alarm pheromone component, 2-ethyl-3,6-dimethylpyrazine (2E36DMP), for several fire ant species. The alarm pheromone component was extracted by soaking ants in hexane for 48 h and subsequently quantified by gas chromatography-mass spectrometry at single ion monitoring mode. Solenopsis invicta workers had more 2E36DMP than male or female alates by relative weight; individual workers, however, contained significantly less pyrazine. We thus believe that alarm pheromones may serve additional roles in alates. Workers of Solenopsis richteri, S. invicta, and hybrid (S. richteri × S. invicta) had significantly more 2E36DMP than a native fire ant species, Solenopsis geminata. The hybrid fire ant had significantly less 2E36DMP than the two parent species, S. richteri and S. invicta. It seems likely that higher alarm pheromone content may have favored invasion success of exotic fire ants over native species. We discuss the potential role of inter-specific variation in pyrazine content for the relationship between the observed shifts in the spatial distributions of the three exotic fire ant species in southern United States and the displacement of native fire ant species.

Parasitoids use odor cues from infested plants and herbivore hosts to locate their hosts. Specialist parasitoids of generalist herbivores are predicted to rely more on herbivore-derived cues than plant-derived cues. Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) is a relatively specialized larval endoparasitoid of Heliothis virescens (F.) (Lepidoptera: Noctuidae), which is a generalist herbivore on several crops including cotton and soybean. Using M. croceipes/H. virescens as a model system, we tested the following predictions about specialist parasitoids of generalist herbivores: (i) naive parasitoids will show innate responses to herbivore-emitted kairomones, regardless of host plant identity and (ii) herbivore-related experience will have a greater influence on intraspecific oviposition preference than plant-related experience. Inexperienced (naive) female M. croceipes did not discriminate between cotton-fed and soybean-fed H. virescens in oviposition choice tests, supporting our first prediction. Oviposition experience alone with either host group influenced subsequent oviposition preference while experience with infested plants alone did not elicit preference in M. croceipes, supporting our second prediction. Furthermore, associative learning of oviposition with host-damaged plants facilitated host location. Interestingly, naive parasitoids attacked more soybean-fed than cotton-fed host larvae in two-choice tests when a background of host-infested cotton odor was supplied, and vice versa. This suggests that plant volatiles may have created an olfactory contrast effect. We discussed ecological significance of the results and concluded that both plant- and herbivore-related experiences play important role in parasitoid host foraging.

Western corn rootworm (WCR), Diabrotica virgifera virgifera is an important pest of maize and the costs of control and yield loss are estimated at $1 billion per year in the USA. As a specialist herbivore, WCR has evolved to use host odors and secondary plant metabolites as cues for host location and phagostimulants. This study reports that rhizobacteria applied as seed treatments to maize affect host-seeking behavior of WCR larvae. The results of a dual-choice test showed that a significantly higher percentage (76%) of WCR larvae chose untreated control plants than plants treated with the single Bacillus pumilus strain INR-7 (24%). In no-choice feeding tests, WCR larvae-fed INR-7-treated plants weighed significantly less than larvae-fed untreated plants or plants treated with bacilli blends. Overall, the results demonstrate that B. pumilus INR-7 can enhance resistance of maize against damage by WCR larvae. The implication of these findings is discussed in the context of using beneficial rhizobacteria in integrated pest management of corn rootworm.

Paratelenomus saccharalis (Dodd) (Hymenoptera: Platygastridae) is an egg parasitoid of Megacopta cribraria (F.) (Hemiptera: Plataspidae). Although the parasitoid has been previously reported in parts of Africa, Europe, Asia, and Australia, it was first reported in North America in 2013 on M. cribraria that was introduced from Asia into North America in 2009. Field observations showed that P. saccharalis females readily parasitize eggs of M. cribraria. However, the cues used by the parasitoid for host location have not been investigated. It was hypothesized that P. saccharalis uses olfactory cues to locate M. cribraria. The objective of this study was to test the attraction of P. saccharalis to host-associated cues in Y-tube olfactometer bioassays. Compared to the control of no host plant or eggs, female P. saccharalis showed significantly greater attraction to M. cribraria-damaged soybean, M. cribraria eggs only, and damaged soybean plus M. cribraria eggs, in separate bioassays. However, the para...

A complex cryptic species taxonomy has been developed for the flies that vector Onchocerca volvulus Leuckart in Africa. This taxonomy names cytoforms of Simulium damnosum Theobald s.l. based on chromosomal inversion polymorphisms. Researchers have linked variation in cytoforms to variation in geographical distributions and biological traits, but have failed to demonstrate that many of these cytoforms are differentiated genetically or morphologically. This may be explained by recent divergence and incomplete lineage sorting of ancestral polymorphisms. Alternatively, it may be the outcome of ongoing gene flow, with inversions maintaining sets of co-adapted alleles and selection driving inversion frequency differences across habitats. Here, our goals were to test species delimitations in the S. damnosum complex, and determine if the poor differentiation between these species is better explained by the ancestral polymorphisms or gene-flow hypotheses. Geometric morphometric analysis and more intensive genetic sampling of populations in Nigeria only reinforced the lack of clear divergence among S. damnosum complex cytoforms. By contrast, the first statistical estimates of evolutionary relationships based on chromosomal inversion polymorphism data revealed clear signs of divergence, which lends support to the ancestral polymorphisms hypothesis. But the latter analyses may be biased by non-neutral evolution of inversion polymorphisms; more rigorous tests of cytoform-based species hypothesis will require deeper sampling across populations and neutral genetic markers along with explicit modelling of genetic isolation and migration.

The role of cis-Jasmone (CJ) in priming plant defense against insect feeding is well documented in the literature. However, little is known about the role of CJ in mediating oviposition behavior of insects via changes in emission of volatile organic compounds (VOCs). Here, we hypothesized that foliar application of CJ will prime induction of plant defense in tomato via enhanced emission of VOCs with consequences for oviposition by Spodoptera exigua, an important pest of tomato. First, we quantified VOCs and the transcript levels of key genes that encode VOC biosynthesis in CJ-treated plants with S. exigua caterpillar infestation (CJI), untreated plants with S. exigua caterpillar infestation (UI), CJ-treated plants without S. exigua caterpillar infestation (CJ), and untreated plants without S. exigua caterpillar infestation (U). Next, oviposition preference of S. exigua was compared between CJI and UI, and between CJ and U. Gas chromatograph coupled-mass spectrometry (GC-MS) analyses showed that several key plant VOCs, including green leaf volatiles, monoterpenes, and a sesquiterpene, were emitted in significantly higher amounts in CJI compared to UI, CJ, or U. Consistent with the GC-MS results, the transcript levels of certain terpene synthase genes involved in the biosynthesis of many VOCs were higher in CJI plants. Consequently, S. exigua laid fewer numbers of eggs on CJI than UI. Moreover, in an in vitro oviposition choice test using filter paper, S. exigua laid significantly fewer eggs on filter papers containing VOCs from CJI compared to UI. These results indicate that CJ treatment followed by caterpillar infestation can prime tomato plant defense with potential ramifications for insect oviposition.

Parasitoids utilize various sugar resources in nature, and rely on odor cues from plants to locate their food and hosts. However, lack of sugar in the diet may negatively impact odor reception in parasitoids, thus affecting foraging efficiency. We used Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), a larval endoparasitoid of Heliothis virescens (F.) (Lepidoptera: Noctuidae), as a model species to test the hypothesis that variation in sugar diet of parasitoids affects their olfactory response to host-related odors. Heliothis virescens is a major pest of cotton and other important crops. Response of female M. croceipes fed different diet treatments (i.e., 40%, 20%, 10%, or 0% sucrose/water solution [w/v]) to select cotton volatiles were tested in electroantennogram (EAG) and Y-tube olfactometer bioassays. The following cotton plant odors were tested: cis-3-hexenol, α-pinene, 50/50 v/v binary mixture of cis-3-hexenol and α-pinene, and H. virescens-infested cotton. Sucrose-fed parasitoids showed higher EAG response to the binary mixture and host-infested plant volatile extract, compared with sucrose-starved (0% sucrose) parasitoids. However, there was no significant difference in EAG response of parasitoids to odor treatments among individuals fed 40%, 20%, or 10% sucrose. In a Y-tube olfactometer, female M. croceipes fed 40% sucrose were significantly more attracted to host-infested cotton than to a control (no plant). However, parasitoids were not significantly attracted to other odor stimuli. These results suggest that the availability of sugar diet affects odor reception in M. croceipes but variation in sugar concentration probably plays a minimal role in olfactory response of M. croceipes to host-related odors.

A parasitoid wasp, Trissolcus basalis (Wollaston), was recorded parasitizing eggs of the invasive stink bug Halyomorpha halys (Stål) in the United States. This is the first record of this species parasitizing fresh and frozen eggs of H. halys in the United States. First record of Trissolcus basalis parasitizing Halyomorpha halys eggs in the United States.

BACKGROUND: A parasitoid wasp, Trissolcus basalis (Wollaston), was recorded parasitizing eggs of the invasive stink bug Halyomorpha halys (Stål) in the United States. This is the first record of this species parasitizing fresh and frozen eggs of H. halys in the United States. NEW INFORMATION: First record of Trissolcus basalis parasitizing Halyomorpha halys eggs in the United States.

The leaffooted bug (Leptoglossus spp.) and phytophagous stink bug species (Euschistus spp., Nezara viridula, Chinavia hilare) are the major hemipteran pests of fruit, vegetable, and grain crops in Alabama and other parts of the southeastern U.S.A. The present study evaluated six winter host crops (hairy vetch, oats, rye, triticale, wheat and winter peas) and six summer host crops (buckwheat, brown top millet, grain sorghum, southern pea, pearl millet and sunflower) as potential trap crops for leaffooted and stink bugs in peaches from 2011 to 2013 in Alabama. Experimental plots were arranged around a mature peach orchard in a randomized complete block design, and insect densities, as well as host plant phenology, were recorded at weekly intervals from March to May and July to August each year. Wheat and oats attracted a significantly higher number of target insects than any other treatments evaluated in the winter trials. Sunflower, pearl millet and sorghum recorded a significantly higher number of insects than any other host crops evaluated in the summer. When the insects sampled were totalled across the season, leaffooted bugs (Leptoglossus phyllopus) dominated the pest complex (>70%), followed by brown stink bugs (mainly Euchistus servus Dallas). Target insects colonized the hosts mainly during the reproductive phase (including flowering and seed development) until plant senescence. The results obtained in the present study suggests that a combination of wheat and oats may be used to detect the early presence of leaffooted and stink bugs in the spring, whereas sunflower, pearl millet and sorghum could be utilized during summer to detect and attract colonizing populations away from peach orchards.

Herbivores emit plant-associated volatile organic compounds (VOCs) after feeding on plants. These plant-associated VOCs can be used by parasitoids to locate their hosts. It is hypothesized that certain compounds play key roles in the attractiveness of host-associated odor blends. The larval parasitoid, Microplitis croceipes (Hymenoptera: Braconidae) and its herbivore host, Heliothis virescens (Lepidoptera: Noctuidae), a major pest of cotton plant were used as model species to identify key compounds mediating attraction of parasitoids to hosts. Comparative GC/MS analyses of cotton-fed vs. artificial diet-fed hosts indicated that 12 of 17 compounds in the headspace of H. virescens larvae were exclusive to plant-fed hosts, and thus considered to be plant-associated. In order to identify key attractive compounds, a full blend of 15 commercially available synthetic compounds was modified by removing each of the 10 plant-associated compounds emitted by host larvae. In Y-tube olfactometer bioassays testing parasitoid responses to modified blends, 1-octen-3-ol, decanal, (E)-β-caryophyllene, α-humulene, α-farnesene, and β-pinene were identified as key compounds contributing to attractiveness of the natural blend of VOCs emitted by cotton-fed hosts. The results showed that while various host-associated compounds act in concert to serve as useful host location cues, only a fraction of the natural blend mediates attraction in parasitoids. Furthermore, the role of a compound is better assessed in the context of other compounds, and odor blends are better perceived as a whole rather than as individual components.

Black rot, caused by Xanthomonas campestris pv. campestris, is the most important and potentially destructive disease of cabbage. The objectives of this study were to select plant growth-promoting rhizobacteria (PGPR) strains and to form strain mixtures with the capacity to elicit induced systemic resistance or to increase plant growth in Chinese cabbage. In preliminary screening, 10 of 12 tested individual PGPR strains (AP136, AP188, AP209, AP213, AP217, AP218, AP219, AP282, AP295, and AP305) reduced the number of foliar lesions, and 2 PGPR strains (AP7 and AP18) increased all tested parameters of plant growth promotion, including shoot fresh weight, shoot dry weight, root fresh weight, root dry weight and plant diameter. In advanced tests, four individual stains (AP136, AP209, AP282 and AP305) were combined into mixture-1. Mixture-2 contained all strains in mixture-1 plus three additional stains (AP7, AP18 and AP218). Both mixtures and three individual strains (AP136, AP209 and AP305) significantly reduced the number of black rot lesions, and mixture-2 increased shoot dry weight and root dry weight in greenhouse tests. In a field test, all the tested treatments significantly reduced disease incidence on whole plants at three weeks after transplanting and reduced head disease severity at harvest time. All treatments also increased marketable yield compared to the nonbacterized control. These results demonstrated that specific individual PGPR strains and strain mixtures induced systemic resistance to black rot in the greenhouse and field.

Sugar feeding is known to enhance lifespan in many parasitoid species. Several species of phorid flies in the genus Pseudacteon (Diptera: Phoridae) have been introduced in the Southern U.S.A. for the biological control of imported fire ants of Solenopsis species (Hymenoptera: Formicidae). Pseudacteon species are short-lived flies and little is known about their nutritional ecology. Results from previous studies in our laboratory show that one of the introduced species, Pseudacteon tricuspis Borgmeier, is capable of feeding on sugar sources with a significant increase in lifespan. However, in Pseudacteon phorid flies, the degree to which sugar feeding can enhance the lifespan of other species is not clear, nor is it known whether there is a relationship between body size and longevity. In the present study, the effect of sugar feeding on the survival of three phorid fly species of different body sizes, Pseudacteon cultellatus Borgmeier, Pseudacteon curvatus Borgmeier and Pseudacteon obtusus Borgmeier, is investigated. For all three species, flies continuously provided with 40% or 20% sucrose solution live longer than individuals provided water only or 40% sucrose solution only on the first day of adult life. However, the degree to which sugar feeding enhanced longevity varies by species and is highest for P. obtusus. The data also indicate that longevity in Pseudacteon phorid flies is related to body size: the largest species (P. obtusus) lives significantly longer than the smaller species (P. cultellatus and P. curvatus). These results suggest that adults of all three Pseudacteon species are capable of feeding on sucrose solution and that sugar feeding can enhance their longevity. The significance of these results is discussed in relation to the field performance of Pseudacteon phorid flies as biological control agents of imported fire ants.

Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) (Xanthomonadales: Xanthomonadaceae), is the most important and potentially destructive disease of cabbage. Twenty-three plant growth-promoting rhizobacteria (PGPR) strains were tested for antibiosis against Xcc in vitro. Seven strains with antibiosis activity significantly reduced disease in the greenhouse. Two mixtures of PGPR strains and four individual strains were then tested three times in the greenhouse and one time in the field. In the greenhouse test, all treatments resulted in significant disease suppression. Mixture-2 and strain AP218 caused the highest and most consistent disease reduction in two of the three trials. In the field test, both mixtures and two individual strains significantly reduced disease incidence and disease severity. In conclusion, mixture-2 exhibited consistent biocontrol of black rot of cabbage.

The invasive brown marmorated stink bug, Halyomorpha halys, is present in the Piedmont and expanding into the Coastal Plains Regions of the southeastern US. Consequently, this study was conducted to evaluate parasitism and predation of H. halys sentinel egg masses by native parasitoids and predators in woodland habitats and orchard, vineyard, row, and vegetable crops alongside these habitats in Alabama and Georgia in 2017 and 2018. Ten primary parasitoid species, including two new records, and one hyperparasitoid emerged from eggs. Trissolcus japonicus was not detected. Ooencyrtus sp. was the prevalent parasitoid species in vegetables while Telenomus podisi was the predominant species in row crops. Anastatus reduvii, An. mirabilis, Tr. brochymenae, and Tr. euschisti were the prevalent species in woodland and orchard habitats. Trissolcus edessae Fouts occurred primarily in orchards. Trissolcus basalis and Gyron obesum were observed in vegetable habitats. Percentage successful development to adults, sex ratio, and percentage of parasitism per egg mass was highest for Tr. edessae. Predation damage included complete and incomplete chewing, stylet sucking, puncture sucking, and removal of whole eggs from egg masses. Hole and non-stylet sucking damage were discovered. Chewing and piercing-sucking predation constituted the majority of predation in woodlands, plum, blueberry, tomato, pecan, peach, and okra. Mainly chewing predation and egg removal occurred in soybean, cotton, and strawberry. Piercing-sucking predation was common in wine grape and apple. There was no difference between fresh and frozen eggs in the proportion of parasitism and predation both years. In 2017, overall percent parasitism was higher for blueberry compared to other crops except peach and apple. No differences were detected in 2018. Peak parasitism (72.3%) in apple at a site in 2017 represented the highest parasitism rate. Predation was highest in soybean and cotton. Indeed, predation in soybean reached very high levels in 2017 (96.3%) and 2018 (90.3%). In conclusion, native natural enemies parasitize and prey on H. halys egg masses in the southeastern US.

Two sibling species, Solenopsis richteri and S. invicta, were both introduced into the southern USA from South America in the early 20th century. Today, S. richteri occupies higher latitudes and colder areas, while S. invicta occupies lower latitudes. Between the distributions of the two species, there is a large area of viable hybrid (S. richteri × S. invicta) populations. This study aimed to characterize the forces driving this distribution pattern and the underlying mechanisms. Cuticular hydrocarbons (CHCs) of freshly killed workers of S. invicta, hybrids, and S. richteri were removed using hexane. Both intact and CHCs-extracted workers were subjected to a constant rate of increasing temperature from 10 to 60 °C to obtain relative water loss and the water loss transition temperature (Tc-ant). Mass loss and Tc-ant were both significantly increased with CHCs removal. We then examined the CHC composition of three species. CHC profiles of S. richteri are characterized by significant amounts of short-chain (C23–C27) saturated and unsaturated hydrocarbons. In contrast, profiles of S. invicta consist primarily of long-chain (C27–C29) saturated hydrocarbons; unsaturated alkenes are completely lacking. Hybrid fire ants show intermediate profiles of the two parent species. We measured the melting point (Tm) and water-loss transition temperature of CHC blends (Tc-CHC) of different ant species colonies using differential scanning calorimetry (DSC) and an artificial membrane system, respectively. There were 3–5 Tms of each CHCs sample of different ant colonies due to their complex chemistry. The highest Tms (Tm-maxs) of CHCs samples from S. invicta and the hybrid were significantly higher than that from S. richteri. The correlation between Tc-CHC and Tm-max obtained from the same CHCs sample was highly significant. These results reveal that species having higher Tc and Tm-max retain more water under relatively higher temperature, and consequently are able to occupy warmer environments. We conclude that CHC chemistry plays a role in shaping current distribution patterns of S. richteri, S. invicta and their hybrid in the United States.

Gossypol is an important allelochemical produced by the subepidermal glands of some cotton varieties and important for their ability to respond to changing biotic stress by exhibiting antibiosis against some cotton pests. Plant growth-promoting rhizobacteria (PGPR) are root-colonizing bacteria that increase plant growth and often elicit defence against plant pathogens and insect pests. Little is known about the effect of PGPR on cotton plant-insect interactions and the potential biochemical and molecular mechanisms by which PGPR enhance cotton plant defence. Here, we report that PGPR (Bacillus spp.) treated cotton plants showed significantly higher levels of gossypol compared with untreated plants. Similarly, the transcript levels of the genes (i.e. (+)-δ-cadinene synthase gene family) involved in the biosynthesis of gossypol were higher in PGPR-treated plants than in untreated plants. Furthermore, the levels of jasmonic acid, an octadecanoid-derived defence-related phytohormone and the transcript level of jasmonic acid responsive genes were higher in PGPR-treated plants than in untreated plants. Most intriguingly, Spodoptera exigua showed reduced larval feeding and development on PGPR-treated plants. These findings demonstrate that treatment of plants with rhizobacteria may induce significant biochemical and molecular changes with potential ramifications for plant-insect interactions.

Tomato spotted wilt virus (TSWV) is a persistent threat to tomato (Solanum lycopersicum L) production, with diseased plants exhibiting reduced growth and direct effects on tomato fruit. TSWV incidence and associated yield losses in tomato plants were assessed with two interrow soil treatments (rye ground cover and bare ground) and four levels of biologic treatments, Make, Agricen, Make + Agricen, and a water control. Tomato plants treated with the biologic formulations in the rye interrow treatment had lower TSWV incidence than the water control, although this did not translate to improved fruit yield. No difference in fruit yield occurred between rye and bare soil interrow treatments. Because biologic treatments reduced TSWV incidence, consideration should be given to integrating them with production practices.

The yellowmargined leaf beetle, Microtheca ochroloma Stål, is a major pest of cruciferous vegetable crops in organic production systems. Very few organically acceptable management options are currently available for this pest. Field studies were conducted at a research station in Alabama and at a commercial organic vegetable farm in Florida to investigate the effectiveness of turnip, Brassica rapa rapa, as a trap crop for M. ochroloma. In the research station trial with cabbage planted as the cash crop, perimeter planting of turnip as a trap crop effectively reduced beetle numbers and crop damage below levels recorded in the control. During the first season of our on-farm trial, with napa cabbage and mustard as the cash crops, using turnip as a trap crop effectively reduced both beetle numbers and cash crop damage below levels found in the control plots, but economic damage was still high. In the second season, beetle populations were too low for significant differences in damage levels to occur between the trap crop and control plots. Together, these results suggest that turnip planted as a trap crop can be an effective control tactic for cruciferous crops, like cabbage, that are much less attractive to M. ochroloma than turnip. In crops, like mustard and napa cabbage, that are equally or only slightly less attractive than turnip, planting turnip as a trap crop would have to be used in combination with other tactics to manage M. ochroloma.

Host preference of Callosobruchus maculatus (F.) on seeds of three legume cultivars, Ife-brown and black-eyed cowpeas [ Vigna unguiculata L. (Walp)], and soybean ( Glycine max L.), was investigated. Mated female C. maculatus showed high (90–95%) attraction to the three legume cultivars in Y-tube bioassays. However, the weevils discriminated among the cultivars in four-choice tests and showed greater attraction to Ife-brown cowpea (50%) than to soybean (30%) and black-eyed cowpea (15%). Coupled gas chromatography-electroantennography (GC-EAD) and GC–MS analyses of the headspace volatile organic compounds (VOCs) emitted by the legume seeds identified 2-ethyl hexanol as the principal EAD active component. Emission of 2-ethyl hexanol was two-fold greater in Ife-brown cowpea (∼0.54 μg g −1 seeds) compared with black-eyed cowpea (∼0.23 μg g −1 seeds) and soybean (∼0.21 μg g −1 seeds). Synthetic 2-ethyl hexanol attracted 68% of female C. maculatus at 0.01 μg dose in Y-tube bioassays. These results demonstrated that host preference in C. maculatus is odor-mediated, and identified 2-ethyl hexanol as a potential attractant for C. maculatus .

Plum curculio,Conotrachelus nenupharHerbst (Coleoptera: Curculionidae), is a key pest of stone and pome fruits in North America. The behavioral response of adults of different physiological states (sex, age, diet, and mating status) to three commercially available synthetic lures, benzaldehyde (BZ) and plum essence (PE), the male-produced aggregation pheromone, grandisoic acid (GA), or their combinations, was studied in the laboratory. Four choice olfactometer bioassays demonstrated significant attraction of both sexes to PE lure. Both BZ and GA lures were not attractive to plum curculio when tested as commercially formulated. PE had higher release rate (1.51 mg/hr) than BZ (0.36 mg/hr) and GA (ca. 0.04 mg/hr), suggesting that the higher attractiveness of PE may be due to its relatively higher release rates. Tests with combined lures showed a neutral effect of combining GA with PE and an inhibitory effect of combining BZ with PE. The physiological conditions of the weevils had no significant effect on their response to the lures. Olfactometer tests with pure 1,2,4-trichlorobenzene (TCB) confirmed that this compound was inhibitory to plum curculio. These results are discussed in relation to the contrasting field reports which implicated BZ + GA as an effective attractant for plum curculio.

Microplitis croceipes and Cotesia marginiventris (Hymenoptera: Braconidae) are parasitoids of lepidopteran larvae with different degrees of host specificity. Both parasitoid species rely on host-related plant volatiles as odor cues to locate their herbivore hosts. To better understand mechanisms of odor processing in parasitoids, we tested responses of olfactory sensory neurons (OSNs) in the antennal sensilla placodea of female parasitoids to select plant volatiles and mixtures. The compounds tested include two green leaf volatiles (i.e., cis-3-hexenol and hexanal) and three herbivore-induced plant volatiles (i.e., cis-3-hexenyl butyrate, cis-3-hexenyl acetate and linalool). Single-sensillum recording showed that the test compounds elicited activity in large and small amplitude neurons housed in the short sensilla placodea of both parasitoid species. In general, C. marginiventris showed greater OSN responses to a low dose while M. croceipes showed greater responses to a high dose of test compounds. Binary mixtures of cis-3-hexenol and linalool inhibited OSN activity in M. croceipes, but not in C. marginiventris. These differences may have implications for odor discrimination in the two parasitoid species. In addition, anterograde neurobiotin stainings were performed to map glomerular projections of OSNs in the antennal lobe of the parasitoids. In M. croceipes, a mixture of cis-3-hexenol and linalool inhibited activity of the glomerulus activated by cis-3-hexenol alone. In C. marginiventris, a mixture of cis-3-hexenol and cis-3-hexenyl acetate showed intense labeling in their respective glomeruli, possibly suggesting a synergistic interaction. These differences in detection and coding of single compounds and mixtures may impact host location strategies in the two parasitoid species.

Several species of Pseudacteon phorid flies, including Pseudacteon cultellatus, P. curvatus, P. obtusus, and P. tricuspis, have been introduced in the southern United States for biological control of imported fire ants, Solenopsis spp. Previous studies showed that Pseudacteon flies use the alarm pheromone and venom alkaloids of fire ants to locate host ant workers. A recent study by our group demonstrated attraction of one of the species, P. tricuspis, to certain alkylpyrazine analogs of fire ant alarm pheromone. If effective, alkylpyrazine analogs of fire ant alarm pheromone may provide cost-efficient alternatives as phorid fly attractants. To test the hypothesis that other phorid fly species are attracted to alkylpyrazine analogs of fire ant alarm pheromone, we compared electroantennogram (EAG) and behavioral responses of four Pseudacteon species, P. cultellatus, P. curvatus, P. obtusus, and P. tricuspis, to the commercially available alarm pheromone isomer (2-ethyl-3,6(or 5)-dimethyl pyrazine) and six structurally related alkylpyrazine analogs at physiologically relevant doses (ranging from picogram to 10 µg). The alarm pheromone isomer and two analogs, 2,3-diethyl-5-methyl pyrazine and 2 ethyl-3,5 + 6 methyl pyrazine, elicited the strongest EAG activity in all four species at all tested doses. Results from four-choice olfactometer bioassays testing the above three EAG-active compounds showed that all four species were strongly attracted to the alarm pheromone isomer at doses ranging from 0.001 to 1 µg. The flies also showed significant attraction to the two analogs (2,3-diethyl-5-methyl pyrazine and 2 ethyl-3,5 + 6 methyl pyrazine) compared to the solvent control but not as strong as the attraction elicited by the alarm pheromone isomer. These results confirm that multiple species of phorid flies use fire ant alarm pheromone as a host location cue. However, the flies are not strongly attracted to the tested alkylpyrazine analogs of the alarm pheromone.

As an indirect defense to herbivore attack, plants release many types of volatile organic compounds (VOCs), which guide parasitoids to their herbivore hosts. In the present study, VOCs were categorized as those released passively from undamaged plants and herbivore-induced plant volatiles (HIPVs). HIPVs were further categorized into: (1) volatiles released by fresh damage plants, and (2) volatiles released by old damage plants. We used as models, two parasitoids with different degree of host specificity, Microplitis croceipes (specialist) and Cotesia marginiventris (generalist), to address the evolutionary and mechanistic question of whether specialist and generalist parasitoids differ in their use of VOCs for host location. Both species are solitary larval endoparasitoids in the same family (Hymenoptera: Braconidae) and are important parasitoids of caterpillar pests of cotton. Based on the results of previous studies, α-pinene, (Z)-3-hexenol, and (Z)-3-hexenyl acetate were selected as representatives of the different types of VOCs in cotton. The attraction of both parasitoid species to synthetic components and a binary mixture of the above VOCs was tested in four-choice olfactometer bioassays. Female M. croceipes showed the greatest attraction to the HIPVs while female C. marginiventris could not discriminate among the three VOCs. Conspecific males showed similar responses with a few exceptions. When presented with the choices; α-pinene, (Z)-3-hexenol and a binary mixture (50:50v/v) of the two compounds, the specialist showed the greatest attraction to the mixture. However, the mixture did not elicit such an additive effect on the attraction of the generalist. Overall response latency (time taken to choose VOCs) indicated species and sexual (in the specialist) differences. Using a simple model, this study provides a fundamental insight into odor preferences and discriminatory ability of the test parasitoids. The ecological significance and practical implications of these results are discussed.

Pseudacteon tricuspis, Pseudacteon obtusus and Pseudacteon curvatus are three species of parasitic phorid flies (Diptera: Phoridae), which have been introduced as classical biological control agents of imported, Solenopsis fire ants (Hymenoptera: Formicidae) in the southern USA. Previous studies demonstrated the behavioral response of P. tricuspis to the venom alkaloids and alarm pheromone of the fire ant, S. invicta. In the present study, we compared the responses of P. tricuspis, P. obtusus and P. curvatus to Solenopsis invicta alarm pheromone, venom alkaloids, or a mixture of both chemicals in four-choice olfactometer bioassays. The main hypothesis tested was that the fire ant alarm pheromone and venom alkaloids act in concert to attract Pseudacteon phorid flies. Both sexes of all three Pseudacteon species were attracted to low doses of the fire ant alarm pheromone or venom alkaloids (i.e. 1 ant worker equivalent) alone. However, the flies were significantly more attracted to a mixture of both chemicals (i.e., 1:1 mixture of alarm pheromone + alkaloids) than to either chemical. The results suggest an additive rather than a synergistic effect of combining both chemicals. Comparing the fly species, P. tricuspis showed relatively greater attraction to cis alkaloids, whereas the alkaloid mixture (cis + trans) was preferred by P. obtusus and P. curvatus. In general, no key sexual differences were recorded, although females of P. tricuspis and P. obtusus showed slightly higher response than conspecific males to lower doses of the alarm pheromone. The ecological significance of these findings is discussed, and a host location model is proposed for parasitic phorid flies involving the use of fire ant alarm pheromone and venom alkaloids as long range and short range attractants, respectively.

The yellowmargined leaf beetle, Microtheca ochroloma Stal (Coleoptera: Chrysomelidae), is a key pest of organic crucifer production in the southern United States. The susceptibility of larvae and adults of M. ochroloma to some botanical and microbial insecticide formulations was evaluated using laboratory leaf-dip bioassays. Insecticides evaluated included OMRI (Organic Material Review Institute) approved formulations of PyGanic® (pyrethrum), Entrust® (spinosad), Mycotrol O® (Beauveria bassiana strain GHA), and NOFLY® (Isaria fumosoroseus strain FE 9901). Others were MBI-203 (experimental organic formulation of Chromobacterium subtsugae) and BotaniGard® 22WP (conventional formulation of Beauveria bassiana strain GHA). The insecticides were first evaluated at the field recommended rate against M. ochroloma larvae and adults, followed by multiple-concentration assays to determine the LC50 and LT50 for promising formulations. At the field recommended rates, all tested formulations were toxic to the ...

The endoparasitic wasps (Hymenoptera: Braconidae), Microplitis croceipes (specialist) and Cotesia marginiventris (generalist), are parasitoids of lepidopteran larvae and differ in their degree of host specificity. Recent studies have reported key differences between the two species in the abundance of antennal olfactory sensilla and their response to host-related volatiles. Here, we have compared antennal lobe architecture and glomerular organization in the two parasitoid species by using a combination of axonal tract tracing techniques and confocal microscopy. In M. croceipes, the medial half of the antennal lobe is larger with a greater number of glomeruli compared with the lateral half, whereas in C. marginiventris, the lateral half is larger than the median half. The volume of the antennal lobe is approximately 2.5 times greater in M. croceipes than in C. marginiventris. However, the number of glomeruli per antennal lobe is only slightly higher in M. croceipes (females: 219-222; males: 220-224) than in C. marginiventris (females: 192-194; males: 193-196). A comparison of males and females within each species demonstrated a striking sexual difference in terms of an enlarged glomerulus (macroglomerulus or MG) at the entrance of the antennal nerve and of a complex of 3-4 MG (CMG) in the posterior region of the antennal lobe of males of both species. Being specific to males, both the MG and CMG might be involved in the detection of female-related odor.

Plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae), is a key pest of peaches in the southeastern United States. Part of its life cycle, specifically, the pre-pupal, pupal and pre-adult stages are spent in the soil. Experiments were conducted in 2 peach orchards to evaluate the effects of some common orchard weed management practices on the development of the soil dwelling life stages of plum curculio. Four common orchard weed management practices (treatments) were evaluated in plots (3 m × 3 m) located under peach tree canopies: centipede grass, Eremochloa ophiuroides (Munro) understory (soil covered with centipede grass); weed free understory (bare soil, weeds removed with herbicide sprays); weedy (natural weeds) understory; and pine bark understory (soil covered with pine bark). Fewer numbers of adult plum curculio emerged from the centipede grass understory plots compared with weed free, weedy or pine bark treated understories. Similar results were obtained in the greenho...

Both cis- and trans-2-methyl-6-undecylpiperidines, MC11P, have been previously reported as the major components of the venom of alate queens of the imported fire ants, Solenopsis richteri (black) and S. invicta (red). To identify the minor components of venom alkaloids from alate queens and compare the venom alkaloid chemistry of alate queen of their hybrid (S. richteri×S. invicta) with that of the two parental fire ant species (S. richteri and S. invicta), silica-gel short-column chromatography was utilized for separating cis-stereoisomers of venom alkaloids from trans-stereoisomers. GC/MS Analyses of venom-alkaloid chemistry of alate queens demonstrated that fewer alkaloid peaks were detected in the chromatograms of the alate queens compared to those of workers. Three new compounds, 7, 12, and 13, were detected as minor components in the venom of alate queens of all three fire ant species. Alate queens of hybrid fire ants showed cis- and trans-alkaloid patterns similar to those of the parental species. Similarity in venom-alkaloid chemistry of alate queens of S. richteri and S. invicta, and their hybrid may indicate their reproductive compatibility in the hybrid zone in southern United States, where all three species occur sympatrically.

The ability of parasitoids to learn a wide range of volatiles, including ecologically relevant and novel odors, and respond favorably to the learned stimuli has been documented for various species. Comparison of odor learning in closely related species can elucidate adaptive differences in species responses to infochemicals. The present study used a Y-tube olfactometer to compare odor learning and priming of behavioral responses of two parasitoids, Cotesia marginiventris (Cresson) and Microplitis croceipes (Cresson), to four selected host-related volatile compounds which have been previously shown to elicit behavioral response in both species; trans-2-hexanal, α-pinene, cis-3-hexenyl butyrate, and (E,E)-α-farnesene. The two parasitoid species differ in their degree of specialization at the host level with M. croceipes having a more specialized host range, but otherwise represent infochemical generalist parasitoid species at the plant level. Naive females as well as females that had been trained to associate sugar water with the test compounds were tested. Compared to naive females, trained females of C. marginiventris showed a significant increase in behavioral response to all four tested compounds. In contrast, trained females of M. croceipes showed a significant increase in behavioral response only to α-pinene, and (E,E)-α-farnesene. Overall, the species with a wider host range, C. marginiventris showed a greater learning-induced increase in response than the species with a relatively specialized host range, M. croceipes. The results imply that animals with different ecological constraints may show variations in learning. The adaptive significance of behavioral responses as related to dietary specializations of the parasitoids is discussed.

The yellowmargined leaf beetle, Microtheca ochroloma Stål (Coleoptera: Chrysomelidae), is an introduced pest of cruciferous crops in the southern United States, and arguably the most damaging pest of organic crucifer vegetable production in the region. Studies were conducted in the greenhouse and laboratory to investigate host finding and acceptance preference of M. ochroloma on four commonly grown cruciferous crops: cabbage (Brassica oleracea L. variety capitata), collards (B. oleracea L. variety acephala), napa cabbage [B. pekinensis (Lour.)], and turnip (B. rapa L.) First, adult beetles were allowed to choose among the four plants in a multiple-choice greenhouse cage experiment and host preference was evaluated by using three parameters: number of beetles on each plant, number of larvae on each plant, and plant damage ratings. The results showed that M. ochroloma adults actively discriminated among the four host plants, with significantly higher numbers recorded on turnip and napa cabbage than on cabbage or collards. Significantly higher numbers of larvae also were recorded on turnip and napa cabbage starting on day 10. Similarly, higher damage ratings were recorded on turnip and napa cabbage than on the remaining two hosts. Results of four-choice olfactometer experiments, which compared attraction of M. ochroloma to headspace volatiles of the four host plants, demonstrated that host preference is mediated primarily by plant volatiles. Both sexes were significantly more attracted to napa cabbage than to the remaining treatments, with turnip being the second most attractive plant. These results confirm that turnip and napa cabbage are two preferred host plants of M. ochroloma, and may support the development of a trap crop system and attractant-based strategies for managing M. ochroloma in crucifer production.

Sublethal effects of larval exposure to indoxacarb on reproductive activities of the diamondback moth, Plutella xylostella (L.) were studied. The third instar male and female larvae of the diamondback moth were fed with collard leaves dipped with a lethal dose of 20% mortality of indoxacarb in order to determine its impact on reproductive activities of adult survivors. Females from indoxacarb treatment had similar peak calling percentage (100%) and mean calling hours (5.83 ± 0.47 h) compared to control females (92% of peak calling, 5.05 ± 0.55 h of mean calling hours) at the first scotophase, but had slightly lower peak calling percentages and shorter calling hours at the subsequent scotophases. The sex pheromone blend or single component from the blend for P. xylostella elicited similar electroantennography responses compared with those from control males and indoxacarb-treated male survivors. Indoxacarb did not alter the number of eggs produced per female and female longevity. However, larval treatment of males with indoxacarb showed a decreased copulation success rate, and this effect was not observed in identically treated female survivors.

Pteromalus cerealellae (Ashmead) (Hymenoptera: Pteromalidae) is an ectoparasitoid of several pests of stored products. We investigated the role of semiochemicals in mediating intraspecific communication in this parasitoid using electroantennogram (EAG) and behavioral bioassays. Responses of virgin male and female P. cerealellae were tested to airborne volatiles from live male and female conspecifics and to whole body extracts of both sexes. Females showed significantly greater EAG responses than males to whole body extracts of both sexes. Results from Y-tube olfactometer bioassays demonstrated significant attraction of both sexes to live conspecifics of the same (intrasexual attraction) or opposite sex (cross attraction). Females also showed significant attraction to whole body extracts of females, but not to the extract of males. These findings provide preliminary evidence for possible existence of a female-produced sex pheromone and close range cuticular chemicals by both sexes of P. cerealellae , which may play a role in courtship and species recognition. Further studies are needed to characterize these chemicals and determine their roles in the behavioral ecology of P. cerealellae .

Pteromalus cerealellae (Ashmead) (Hymenoptera: Pteromalidae) is a generalist parasitoid of the larvae of many stored-product insects, including the cowpea seed beetle, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), which live endophytically in cowpea seeds. The role of host-related semiochemicals in the host location behavior of this parasitoid was investigated using electroantennogram (EAG) and behavioral (olfactometer) techniques. Responses of mated and unmated female P. cerealellae were tested to a variety of host-related chemical stimuli including hexane extracts of uninfested cowpea seeds, (bruchid)-infested cowpea seeds, bruchid larvae (whole body or WB), larval frass, adult female bruchids (WB), and adult male bruchids (WB). All of the tested stimuli elicited significant EAG responses in unmated and mated female P. cerealellae, with mated females exhibiting a greater EAG response than unmated females to some treatments. Results from Y-tube olfactometer bioassays demonstrated a significant response of mated female P. cerealellae to extracts of uninfested cowpea seeds, infested cowpea seeds, adult female bruchids, bruchid larvae, and larval frass, but no significant response was elicited by the extract of adult male bruchids. Pair-wise comparisons of the four most attractive stimuli (i.e. uninfested seeds, infested seeds, bruchid larvae, and larval frass) in a four-way olfactometer showed preference of mated female P. cerealellae for the extract of uninfested cowpea seeds compared to larval frass extract. No significant differences were recorded between other paired treatments. These results suggest the relative importance of volatile cues from seeds (host habitat) in mediating host location by P. cerealellae.

The plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), is a key pest of peaches, Prunus persica (L.) Batsch, in North America. Captures of adult weevils in unbaited pyramid traps recorded annually from 2000 to 2008 in an unmanaged peach orchard in central Alabama were used to determine its seasonal occurrence and to develop predictive degree-day models. Spring migration of plum curculio began at bloom (early to mid-March). Linear, polynomial, and three-parameter Weibull functions were tested to describe the relationship between weekly trap capture and cumulative degree-day (DD). Criteria used to select the best models were the smallest Akaike information criterion and highest R2 values. A sixth-order polynomial function fitted best to seasonal trap captures and cumulative DDs and revealed two major seasonal peaks with the first (spring generation) and second (summer generation) peaks occurring at cumulative DDs of ≈245 and 1105 (base 10°C, biofix of 1 January), respectively. A potential third (late summer generation) peak was observed at 1758 DDs. The sixth-order polynomial model predicted the first trap capture to occur at cumulative DD of ≈99 (base 10°C, biofix of 1 January). The three-parameter Weibull model predicted the first trap and first peak (spring generation) trap captures to occur at mean cumulative DDs of 108.02 ± 9 and 220.07 ± 16, respectively. Validation of the models in the unmanaged orchard in 2009 and 2010 and in a second unmanaged orchard (located 1.6 km from the first) in 2009 showed that the polynomial and Weibull were within ±7 d in their predictions of the first and peak trap captures of the spring population. Validation results showed that both models successfully predicted the first trap capture in one out of three scenarios and the peak trap capture in two out of three scenarios. The performance of the models is discussed in relation to management of plum curculio in central Alabama.

In support of an ongoing study to evaluate potential farmscaping plants for utilization in organic vegetable production systems, we examined the effects of the nectar of three flowering plant species, sweet alyssum ( Lobularia maritima ), buckwheat ( Fagopyrum sagittatum ), and licorice mint ( Agastache foeniculum ), on the lifespan and body nutrient levels of the wasp, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), a key parasitoid of some caterpillar pests of vegetable crops in the USA. The greatest longevity (∼16 days) was recorded for honey-fed wasps (positive control). Buckwheat significantly increased the lifespan of female and male wasps by at least two-fold relative to wasps provided water only (longevity = 3–4 days). Licorice mint significantly increased female longevity and numerically increased male longevity. Sweet alyssum slightly increased longevity of both sexes but this was not significantly different from the water only control. Females had a significantly longer longevity than males on all the diet treatments. The greatest carbohydrate nutrient levels (sugar content and glycogen) were recorded in honey-fed wasps followed by wasps fed buckwheat, whereas very little nutrients were detected in wasps provided sweet alyssum, licorice mint or water only. However, female wasps were observed to attempt to feed on all three flowering plant species. Thus, the low nutrient levels detected in wasps provided sweet alyssum or licorice mint may be because the nectars were not accessible or were of poor quality. Further studies will evaluate the effects of the promising farmscaping plants on the beneficial and pest insect communities in the field.