Induced volatiles provide a signal to foraging predatory insects about the location of their prey. In Iowa, early in the growing season of soybean, Glycine max, many predacious seven-spotted lady beetles, Coccinella septempunctata, were observed on plants with heavy infestations of soybean aphid, Aphis glycines. We studied whether the attraction of this beetle is caused by the release of specific volatile compounds of soybean plants infested by aphids. Volatile compounds emitted by soybean plants infested by aphids were compared with those of undamaged, uninfested, and artificially damaged plants. Gas chromatography-mass spectrometry analyses revealed consistent differences in the profiles of volatile compounds between aphid-infested soybean plants and undamaged ones. Significantly more methyl salicylate was released from infested plants at both the V1 and V2 plant growth stages. However, release patterns of two other induced plant volatiles, (D)-limonene and (E,E)-alpha-farnesene, differed between the two plant growth stages. Gas chromatographic-electroantennographic detection of volatile extracts from infested soybean plants showed that methyl salicylate elicited significant electrophysiological responses in C. septempunctata. In field tests, traps baited with methyl salicylate were highly attractive to adult C. septempunctata, whereas 2-phenylethanol was most attractive to the lacewing Chrysoperla carnea and syrphid flies. Another common lady beetle, the multicolored Asian lady beetle, Harmonia axyridis, showed no preference for the compounds. These results indicate that C. septempunctata may use methyl salicylate as the olfactory cue for prey location. We also tested the attractiveness of some selected soybean volatiles to alate soybean aphids in the field, and results showed that traps baited with benzaldehyde caught significantly higher numbers of aphids.

The Noctuidae are one of the most speciose moth families and include the genera Helicoverpa and Heliothis. Females use (Z)-11-hexadecenal as the major component of their sex pheromones except for Helicoverpa assulta and Helicoverpa gelotopoeon, both of which utilize (Z)-9-hexadecenal. The minor compounds found in heliothine sex pheromone glands vary with species, but hexadecanal has been found in the pheromone gland of almost all heliothine females so far investigated. In this study, we found a large amount (0.5-1.5 μg) of hexadecanal and octadecanal on the legs of males of four heliothine species, Helicoverpa zea, Helicoverpa armigera, H. assulta, and Heliothis virescens. The hexadecanal was found on and released from the tarsi, and was in much lower levels or not detected on the remaining parts of the leg (tibia, femur, trochanter, and coxa). Lower amounts (0.05-0.5 μg) of hexadecanal were found on female tarsi. This is the first known sex pheromone compound to be identified from the legs of nocturnal moths. Large amounts of butyrate esters (about 16 μg) also were found on tarsi of males with lower amounts on female tarsi. Males deposited the butyrate esters while walking on a glass surface. Decapitation did not reduce the levels of hexadecanal on the tarsi of H. zea males, indicating that hexadecanal production is not under the same neuroendocrine regulation system as the production of female sex pheromone. Based on electroantennogram studies, female antennae had a relatively high response to hexadecanal compared to male antennae. We consider the possible role of aldehydes and butyrate esters as courtship signals in heliothine moths.

Drosophila suzukii differs from other members of the genus Drosophila in its host preference and oviposition behavior. The flies are attracted to ripening fruits, and females have a serrated ovipositor enabling eggs to be laid inside the fruit. In addition to its huge economic impact, its unique chemoecological, morphological, and physiological characteristics have garnered considerable research interests. In this study, we analyzed D. suzukii antennal transcriptomes to identify sex‐biased genes by comparison of differential gene expressions between male antennae (MA) and female antennae (FA). Among 13,583 total genes of the fly genome, 11,787 genes were expressed in either MA or FA. There are only 132 genes (9 in MA, 7 in FA, and 116 in both, FPKM >1) were expressed in antennae exclusively, and 2,570 genes (9 in MA, 0 in FA, and 2,561 in both) were enriched in antennae containing 185 and 113 sex‐biased genes in MA and FA, respectively. Interestingly, many immune‐related genes were highly expressed in MA, whereas several chemosensory genes were at high rank in FA. We identified 27 sex‐biased chemosensory genes including odorant and gustatory receptors, odorant‐binding proteins, chemosensory proteins, ionotropic receptors, and cytochrome P450s, and validated the gene expressions using quantitative real‐time PCR. The highly expressed sex‐biased genes in antennae are likely involved in the fly specific mating, host‐finding behaviors, or sex‐specific functions. The molecular results demonstrated here will facilitate to find the unique chemoreception of D. suzukii, as well as on the development of new management strategies for this pest.

The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean production in North America, after having spread to >20 states in the United States and several southern provinces of Canada. Control of A. glycineshas focused on applications of insecticides, which are not a long-term solution to soybean aphid pest management. In autumn, soybean aphids start producing alate females (gynoparae) that search for their overwintering host plants, the common buckthorn, Rhamnus cathartica. The gynoparae then produce pheromone-emitting wingless female offspring (oviparae) that attract male aphids. In this study, we report the chemical identification of the soybean aphid sex pheromone using gas chromatography-electroantennogram, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy. Behavioral activities of males and gynoparous females in the field were also characterized. The potential applications using formulations containing specific soybean aphid pheromone compositions for reducing overwintering populations are discussed. RightsThis article is the copyright property of the Entomological Society of America and may not be used for any commercial or other private purpose without specific written permission of the Entomological Society of America. ABSTRACT The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean production in North America, after having spread to Ͼ20 states in the United States and several southern provinces of Canada. Control of A. glycines has focused on applications of insecticides, which are not a long-term solution to soybean aphid pest management. In autumn, soybean aphids start producing alate females (gynoparae) that search for their overwintering host plants, the common buckthorn, Rhamnus cathartica. The gynoparae then produce pheromone-emitting wingless female offspring (oviparae) that attract male aphids. In this study, we report the chemical identiÞcation of the soybean aphid sex pheromone using gas chromatographyÐ electroantennogram, gas chromatographyÐmass spectrometry, and nuclear magnetic resonance spectroscopy. Behavioral activities of males and gynoparous females in the Þeld were also characterized. The potential applications using formulations containing speciÞc soybean aphid pheromone compositions for reducing overwintering populations are discussed. AuthorsKEY WORDS sex pheromone, artiÞcial induction of pheromone-emitting females, (1R,4aS,7S,7aR)-nepetalactol, (4aS,7S,7aR)-nepetalactone, Þeld trapping