Anjel M. Helms

Manure is an abundant waste source in dairy production with disposal creating significant challenges for producers. Recent work has shown that black soldier fly, Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae), larvae can digest dairy manure; however, its high cellulose content and low nutrient value impact larval performance. Adding probiotics to black soldier fly feed can increase feed digestibility and weight gain. The goal of this study was to determine the influence of probiotic additions on black soldier fly larval performance when fed dairy manure. This study evaluated life-history traits of black soldier fly larvae fed dairy manure with single or combined probiotic treatments: Rhodococcus sp., Paenibacillus sp., and 1:1 combination, compared to a no-microbe control. Larvae were mass-reared on fresh dairy manure, and key metrics—bioconversion rate, survivorship, total biomass, and larval weight—were compared across treatments. Results showed a significant trial effect for all variables measured. Mean peak weights and the largest larval weights were 3.5-20.0% greater in at least one probiotic treatment compared to the control, while other life-history traits did not differ significantly. However, probiotic treatments reduced variation up to 17.0% in black soldier fly larval weight across trials, a trait not historically discussed in black soldier fly research. Developing processes that optimize larval weight in combination with reducing variation are critical for developing precise business models for predicting future production.

Summary: Soybean aphids ( Aphis glycines ) can induce susceptibility on soybean ( Glycine max ) during colonization. However, the mechanism for this process is not known. Based on previous transcriptome analyses, we hypothesized that aphids block effective jasmonate (JA) defenses by inducing an antagonistic abscisic acid (ABA) signal. To test this hypothesis, we used a combination of gene expression analyses, measurements of hormone levels, and aphid bioassays on plants with reduced expression of ABA-related genes. Aphid feeding attenuated JA responses in soybean plants and facilitated the growth of a chewing herbivore. Aphid-treated plants had increased levels of cis -JA but not biologically active JA-isoleucine, and aphid feeding induced expression of genes associated with JA-Ile catabolism. In parallel, aphid-feeding induced higher levels of ABA. ABA treatment and knockdown lines impaired in ABA biosynthesis ( aba2 -RNAi) or signaling ( scof-1 -RNAi), showed that ABA suppressed wound-induced JA responses. Aphid populations were significantly reduced on ABA-deficient plants and aphid-regulated attenuation of JA signaling was abolished in these lines. Remarkably, plants defective in ABA signaling had increased JA signaling in the absence of stressors. Our results indicate that, in soybean, the ABA pathway is necessary to control basal levels of JA and soybean aphids exploit this ABA-JA antagonism to suppress plant defenses.

Black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae convert organic wastes into insect biomass that can be used as livestock feed. Recent evidence also suggests larvae can reduce emissions of greenhouse gases (GHG) and noxious odors. However, these benefits are substrate and scale dependent. The current study examined the impact of black soldier fly larval digestion on resulting moisture level, greenhouse gas (i.e., carbon dioxide), noxious gases (i.e., ammonia, carbon monoxide, and hydrogen sulfide), and volatile organic compound production for coconut, honeydew, orange, and control (Gainesville diet) substrates at an industrial scale. Overall, the moisture content for some substrates digested by larvae was significantly (P < 0.05) lower (>20%) than those without larvae. However, differences were substrate dependent with final moisture content ranging from 35% (coconut) to 52% (oranges). The presence of black soldier fly larvae did not significantly (P > 0.05) impact overall GHG emissions. However, significant differences were detected at select days of the experiment. From an industrial perspective, recycling waste with larvae (7-d process) would potentially result in reduced duration for producing GHG versus placing substrates in a landfill (i.e., weeks to months to compost). The presence of black soldier fly larvae significantly (P < 0.05) impacted overall volatile organic compound profiles of the substrates. Larval impact on volatile abundance, richness, and evenness was substrate dependent. These results demonstrate the need to formulate diets and engineer systems that maximize benefits associated with black soldier fly larvae, while minimizing greenhouse gas and volatile organic compound emissions.

The cotton fleahopper, Pseudatomoscelis seriatus, is a piercing-sucking insect that feeds on several plant species, including squares (pre-floral buds) of upland cotton, Gossypium hirsutum, causing square abscission and yield reductions. Current control of cotton fleahoppers relies on pesticide applications, but there is growing interest in using chemical ecology to develop more sustainable methods for integrated pest management. Herbivore foraging behavior is often mediated by plant-produced volatile organic compounds (VOCs), which can serve as attractants or repellants during host-plant selection. This study aimed to evaluate the influence of cotton fleahopper herbivory on VOC emissions from cotton squares under field conditions and to investigate the behavioral responses of conspecific insects to these VOCs. Using dynamic headspace sampling, we identified seven VOCs emitted from cotton squares, with three compounds emitted in higher abundance following cotton fleahopper herbivory: (E)-β-ocimene, (E)-β-caryophyllene, and (E)-β-farnesene. The total emission of VOCs from squares with cotton fleahopper herbivory was greater than non-damaged (control) cotton squares. Using dual choice olfactometer assays, we found that adult cotton fleahoppers preferred VOCs from non-damaged squares compared to VOCs from squares with conspecific herbivory. Furthermore, cotton fleahoppers were attracted to synthetic (E)-β-ocimene but repelled by synthetic (E)-β-caryophyllene or the combination of (E)-β-ocimene and (E)-β-caryophyllene. Our findings suggest that cotton VOCs influence cotton fleahopper foraging, and that compounds identified in this study have potential for development as lures or repellants to use in integrated pest management.

Cotton fleahopper, Pseudatomoscelis seriatus Reuter (Hemiptera: Miridae), is an early season pest of upland cotton, Gossypium hirsutum L. Feeding damage from this pest causes square abscission. The response of commercial cotton cultivars with varying maturity traits to cotton fleahopper feeding was assessed. The hypothesis was that feeding affects early and late-maturing cultivars differently in maturity delays and yield. Field experiments with natural and artificial infestations were conducted in Corpus Christi, TX. For the natural infestation experiment, 4 cultivars (DP 2020 B3XF, DP 2012 B3XF, PHY 332 W3FE, and PHY 545 W3FE) were assigned to main plots, with subplots either sprayed or not sprayed with thiamethoxam insecticide to control cotton fleahopper early in the season. The artificial infestation experiment used 2 cultivars (DP 2020 B3XF and PHY 545 W3FE) as main plots, with subplots infested to or not infested with cotton fleahopper using single square caging. In the no-spray subplots of the natural infestation experiment, cotton fleahopper feeding increased square abscission, leading to yield loss and delayed boll maturity, especially in cultivars classified as late-maturing. Early maturing cultivars consistently showed faster boll opening regardless of cotton fleahopper. Artificial infestation experiments further confirmed increased square abscission, reduced boll numbers, and lower lint weights when infested with cotton fleahopper. Early maturing cultivars are more resilient and may be particularly useful in areas with high cotton fleahopper pressure, especially when scheduling an early harvest is desirable.

The leaffooted bug, Leptoglossus phyllopus (L.) (Hemiptera: Coreidae), probes and feeds on tissues of many plant species, including developing cotton bolls, causing seed damage and abscission. Insecticides are the primary tool for managing leaffooted bugs, but concerns about resistance and environmental harm highlight the need for alternative management strategies. One promising approach is using semiochemicals, such as plant- and insect-produced volatile organic compounds (VOCs), to trap or repel pests. Insect herbivores often use plant-produced VOCs to select suitable host plants for feeding and oviposition. Field observations of abundant adult leaffooted bugs on cotton bolls suggest that bugs aggregate at feeding sites. The goal of this study was to characterize VOCs from developing cotton bolls with and without leaffooted bug herbivory and evaluate how these VOCs affect adult bug foraging behavior. A portable dynamic headspace sampling method was used to collect VOCs from developing cotton bolls in the field, and VOC samples were analyzed using gas chromatography–mass spectrometry. Leaffooted bug herbivory induced volatile emissions from cotton bolls, with significant increases in the emissions of six compounds (benzaldehyde, α-pinene, β-pinene, β-myrcene, p-xylene, and (E)-β-caryophyllene). Dual-choice olfactometer assays revealed that adult leaffooted bugs were attracted to VOCs from damaged cotton bolls, as well as being attracted to synthetic benzaldehyde or α-pinene individually. In contrast, leaffooted bugs were repelled by the combination of synthetic benzaldehyde and α-pinene. These findings suggest that VOCs from cotton bolls are attractive to leaffooted bugs and could contribute to the development of attractive lures for integrated pest management.

Collective behaviors of social insects are often regulated by pheromones. In subterranean termites, some workers forage for and exploit decaying wood for new food resources while forming tunnels from their nest. Colonizing new food resources requires workers to build and disinfect tunnels and chambers inside the nest and ingest decaying wood; therefore subterranean termite colonies should have mechanisms to establish and maintain groups of workers to perform these functions. Recently, an aggregation pheromone was identified in workers of the termite Reticulitermes speratus, which induces quick attraction of nestmate workers and prolonged aggregation to the site of attraction. In this study, we extended this work to another species of Reticulitermes and identified a worker aggregation pheromone in the termite R. virginicus. GC–MS analysis and bioassays demonstrated that this pheromone consists of 3-octanone, 3-octanol, and palmitic acid and shows a colony-specific, dose-dependent attractant response but not an arrestant response. Furthermore, these pheromone components were most likely emitted from the surface of the body. This suggests that aggregation pheromone composition and function differ significantly among termite species, even within the same genus. This study advances our understanding of the regulatory mechanisms of termite aggregation behavior.

When attacked by insect herbivores, plants emit blends of chemical compounds known as herbivore‐induced plant volatiles (HIPVs). Although HIPVs are produced both aboveground and belowground, how HIPVs vary across plant tissues remains unresolved, as do the selective forces shaping interspecific HIPV emission patterns. Here, we compared foliar and root HIPVs within and among closely related plant species and evaluated if different eco‐evolutionary forces, including plant domestication, coexistence histories with herbivores, or phylogenetic relatedness, explain HIPV blends. To examine aboveground and belowground patterns in HIPVs, we compared leaf and root volatile profiles for six species in the Cucurbitaceae that differed in domestication status and coexistence history with specialist insect herbivores. We predicted that within‐species HIPVs from different tissues would be more similar than HIPV blends among different species, and that plant volatile chemodiversity was reduced by domestication and enhanced by coexistence histories with herbivores. We found that herbivory induced both quantitative and qualitative changes in volatile emissions across all plant species, which were more pronounced aboveground than belowground. Each species produced tissue‐specific HIPVs, and foliar and root HIPVs differed among species. Contrary to our predictions, plant domestication enhanced foliar volatile diversity, while coexistence histories with herbivores reduced foliar and root volatile diversity. Additionally, phylogenetic relatedness did not correlate with aboveground or belowground volatiles. Overall, this work furthers our understanding of the eco‐evolutionary forces driving patterns in aboveground and belowground HIPV emissions, elucidating an important and previously undescribed component of within‐plant variation in chemodiversity.