Theocolax elegans (Hymenoptera: Pteromalidae) is a potential postharvest biocontrol agent whose host range includes Sitophilus oryzae (Coleoptera: Curculionidae) and Rhyzopertha dominica (Coleoptera: Bostrichidae). Both host species are cosmopolitan and destructive pests of bulk wheat. In addition, either species could be used when mass rearing T. elegans. The Hopkins-Host Selection principle suggests the natal host environment (e.g., the habitat in which a wasp emerges from a pupa) may influence the semiochemicals an organism utilizes when foraging for oviposition sites. Thus, later efficacy may be impaired if important semiochemicals are lost from the foraging repertoire of T. elegans. In order to investigate the impact of natal host environment on the behavioral response of T. elegans to potential hosts, we reared T. elegans on either S. oryzae or R. dominica for multiple generations. We then evaluated the orientation and taxis of T. elegans to six treatments: S. oryzae, R. dominica, damaged grain + S. oryzae, damaged grain + R. dominica, damaged grain + insects from the natal environment, or an undamaged control. We found T. elegans reared on R. dominica most preferred damaged grain from R. dominica in a four-way olfactometer, which was 4.2-fold more often chosen than S. oryzae individuals alone. Treatments containing R. dominica were differentiated from others based on headspace volatiles while S. oryzaeinfested grain generally overlapped with uninfested grain. Both rearing host and subsequent foraging host affected efficacy of T. elegans released in a pilot-scale elevator. Wasps appeared most effective in suppressing grain damage by 35-38 % when reared on R. dominica and foraging for R. dominica compared to S. oryzae-reared wasps that only reduced damage by 1-18 %. Sitophilus oryzae-reared wasps only effectively foraged on hosts up to 0.5 m, while R. dominica-reared wasps foraged successfully up to 4 m. Overall, we found that the natal host and chemical cues significantly affected taxis and foraging by T. elegans, suggesting that careful attention should be paid to the mass rearing procedure for this parasitoid.

There has been a dearth of research elucidating the behavioral effect of microbially-produced volatile organic compounds on insects in postharvest agriculture. Demonstrating attraction to MVOC's by stored product insects would provide an additional source of unique behaviorally-relevant stimuli to protect postharvest commodities at food facilities. Here, we assessed the behavioral response of a primary (Rhyzopertha dominica) and secondary (Tribolium castaneum) grain pest to bouquets of volatiles produced by whole wheat that were untempered, or tempered to 12%, 15%, or 19% grain moisture and incubated for 9, 18, or 27 days. We hypothesized that MVOC's may be more important for the secondary feeder because they signal that otherwise unusable, intact grains have become susceptible by weakening of the bran. However, contrary to our expectations, we found that the primary feeder, R. dominica, but not T. castaneum was attracted to MVOC's in a wind tunnel experiment, and in a release-recapture assay using commercial traps baited with grain treatments. Increasing grain moisture resulted in elevated grain damage detected by near-infrared spectroscopy and resulted in small but significant differences in the blend of volatiles emitted by treatments detected by gas chromatography coupled with mass spectrometry (GC-MS). In sequencing the microbial community on the grain, we found a diversity of fungi, suggesting that an assemblage was responsible for emissions. We conclude that R. dominica is attracted to a broader suite of MVOC's than T. castaneum, and that our work highlights the importance of understanding insect-microbe interactions in the postharvest agricultural supply chain.

There is a large suite of insects that attack anthropogenic agricultural goods after harvest. Proper sanitation programs for food facilities are now recognized as the foundation of good integrated pest management (IPM) programs for stored products throughout the post-harvest supply chain. While good sanitation programs are generally thought to reduce the abundance and diversity of insects, there has been less appreciation of the manifold ways that sanitation interacts with a range of other IPM tactics to modulate their efficacy. Here, we review the literature on how the effectiveness of chemical, physical/cultural, biological, and behaviorally-based control tactics varies with changes in sanitation. In addition, we discuss how sanitation may affect ongoing pheromone- and kairomone-based monitoring programs. Where possible, we quantitatively compile and analyze the impact of sanitation on the fold-change in the efficacy of IPM tactics. We found that decreased sanitation negatively affected the efficacy of most tactics examined, with a mean 1.3–17-fold decrease in efficacy under poorer sanitation compared to better sanitation. Sanitation had neutral or mixed impacts on a few tactics as well. Overall, the literature suggests that sanitation should be of the utmost importance for food facility managers concerned about the efficacy of a wide range of management tactics.

There are several species of spiders in the midwestern United States that cohabit with humans, but probably the most concerning is the brown recluse spider, Loxosceles reclusa, (Araneae: Sicarlidae) because of the potential for a venomous bite. Thus, managing the brown recluse spider is a continuous endeavor. Essential oils (EOs), i.e. specific plant extracts, have often been used to control or deter other arthropods and pests. In this study, several EOs were selected to test their effectiveness as alternatives to synthetic pesticides for L. reclusa control. Spiders were exposed to EOs by direct contact or as a fumigant (inhalation) treatment for 24 h, and mortality was recorded. Physical contact with the oils resulted in the greatest mortality, with wintergreen, peppermint and lavender to a lesser extent, showing potential for L. reclusa control. Mortality attributed to lemon, lemongrass or wild orange was too low to provide effective reduction of L. reclusa populations. Fumigants (inhalation) caused less mortality than contact treatments, never resulting in more than 20%. Two EOs, wintergreen and peppermint, demonstrated effective toxicity to L. reclusa and may have potential as alternatives to synthetic pesticides for this pest, warranting further investigation.

Studies were conducted to determine if predation versus scavenging versus scavenging on insecticide-killed prey affected brown recluse spiders, Loxosceles reclusa. Indicators of possible effects were measured by weight change and survival. Live house crickets, Acheta domesticus, used as prey, were exposed to one of four treatments: live (untreated control), Spinosad or pyrethroid insecticide treated surface, or freeze-killed (scavenging control) and made available to spiders for twenty-four hours once/week for eight weeks. Spiders fed pyrethroid-killed crickets had significantly lower survival than did spiders utilizing crickets exposed to all other treatments. L. reclusa had significantly greater weight gain feeding as predators than as scavengers.