摘要: Ants use species-specific trail pheromones to coordinate their sophisticated foraging behavior. During the past decades, many trail pheromone components with various structures have been identified in ants, including the red imported fire ant, Solenopsis invicta, a notorious invasive species worldwide. Four compounds, Z,E- (ZEF) and E,E-alpha-farnesene (EEF), Z,E- (ZEHF) and E,E-alpha-homofarnesene (EEHF), have been reported as components of S. invicta trail pheromone. However, another study reported an analog of alpha-farnesene, Z,Z,Z-allofarnesene, as a key trail pheromone component. These contrasting results caused some uncertainty about the trail pheromone composition in S. invicta. In this study, we synthesized ZEF and EEF, ZEHF and EEHF, and reanalyzed the chemicals in the Dufour gland extract and in the trail pheromone fraction of S. invicta worker body extract. The reported isomers of farnesene and homofarnesene were detected and showed trail-following activity, with ZEF as the major compound, while no allofarnesene was found, neither in the Dufour gland extract nor in the whole-body extract. Our results confirm ZEF and EEF, ZEHF and EEHF as trail pheromone components of S. invicta.

摘要: Field monitoring revealed that the infection ratio of the bacterial symbiont Cardinium in the whitefly (Bemisia tabaci MED) was relatively low in northern China. However, the role of this symbiont and the symbiont-whitefly-host plant interaction mechanism are poorly understood. We investigated the influence of Cardinium on the competitiveness of the host whitefly and the physiological interaction between the host plants and host whiteflies. Cardinium-infected whiteflies were displaced by uninfected whiteflies after 5 generations, which showed that Cardinium infection reduced whitefly competitiveness. The defense response genes of cotton significantly decreased under infestation by infected whiteflies compared to uninfected whiteflies. The expression of detoxification metabolism genes, especially the uridine 5MODIFIER LETTER PRIME-diphospho-glucuronyltransferase and P450 genes, in infected whiteflies significantly decreased. These results demonstrated that Cardinium could inhibit the defense response of the host plant and decrease the detoxification metabolism ability of the host whitefly. The reduced competitiveness of infected whiteflies may be associated with the inhibition of the whitefly detoxification metabolism by Cardinium, resulting in the reduced performance of infected whiteflies. However, Cardinium infection can suppress plant defenses, which may benefit both infected and uninfected whiteflies when they coexist. This research illustrates the symbiont-whitefly-host plant interaction mechanism and the population dynamics of the whitefly.

摘要: Olfaction plays a crucial role for arthropods in foraging, mating, and oviposition. The odorant-binding protein (OBP) gene is considered one of the most important olfactory genes. However, little is known about its functions in predatory mites. Here, we used Neoseiulus barkeri, an important commercialized natural pest control, to explore the chemosensory characteristics of OBP. In this study, N. barkeri was attracted by methyl salicylate (MeSA) and showed higher crawling speeds under MeSA treatment. Then, we identified and cloned an OBP gene named Nbarobp2 and analyzed its expression profiles in the predatory mite. Nbarobp2 was 663 bp, was highly expressed in larval and nymphal stages, and was significantly upregulated in N. barkeri under MeSA treatment. Nbarobp2 encoded 202 amino acid residues with a molecular weight of 23 kDa (after removing the signal peptide). Sequence comparisons revealed that the OBPs in Arachnida shared 6 conserved cysteine sites, but were distinguishable from the OBPs of Insecta on the phylogenetic tree. RNA interference, Western blotting, and binding affinity assays further proved that Nbarobp2 was involved in volatile perception in predatory mites. This study shed light on the functional characteristics of OBPs in predatory mites, providing a new insight for better biological control.

摘要: The complex and efficient sex pheromone communication system in insects is essential for reproduction and for reproductive isolation of species. In moths, sex pheromone communication starts with male attraction to compounds emitted by females; only a few species act in the reverse. However, how the pheromones that are emitted by both sexes co-regulate and coordinate mate finding and mating remains unknown. Here, we identified both the male and female pheromones of Eastern Grass Veneer moth, Agriphila aeneociliella (Lepidoptera: Crambidae), and demonstrated their efficiency in manipulating behavioral responses of the opposite sex. Combining data from analysis of gas chromatography-electroantennogram detection, gas chromatography-mass spectrometry, and olfactory behavior assays, the female pheromone of A. aeneociliella was identified as (Z,Z,Z)-9,12,15-octadecatrienal and (Z)-9-hexadecenyl acetate, while the male pheromone was determined to be 1-nonanal. Both the 2 individual components of the female pheromone and their binary mixture were significantly attractive to males, and the 1-nonanal male pheromone induced strong electrophysiological responses in females and induced attraction of females in a Y-tube olfactory test. Depending on the concentration of 1-nonanal, its addition to the binary mixture of the female pheromone either enhanced (10(-3) or 10(-2) mu g/mu L) or reduced (1 mu g/mu L) the aphrodisiac effect of the mixture on males. In wind-tunnel bioassays, different concentrations of pheromones, including the binary mixture of female pheromone and the mixture of male and female pheromones, had significant effects on male behavior. Our findings suggested that the blend of both female and male pheromones plays a significant role in the sexual communication system in some moths.

摘要: The rice stem borer, Chilo suppressalis, has developed a high level of resistance to many of the compounds currently used for control. There is therefore an urgent need to develop novel control methods for C. suppressalis. Insect chitin synthases (CHS) have attracted interest as a potential target for insect pest management. However, to date, CHS have not been characterized in C. suppressalis. Two CHS genes (CsCHS1 and CsCHS2) were identified and cloned from C. suppressalis. Two transcript variants were identified for CsCHS1, CsCHS1a and CsCHS1b. Spatiotemporal expression profiling showed that both transcripts of CsCHS1 are most highly expressed on the last day of each larval instar stage and show the highest expression levels in the integument. In contrast, CsCHS2 is predominantly expressed during the larval feeding stages and shows the highest expression levels in the midgut. Knockdown of CsCHS1 by RNA interference significantly inhibited the molting and pupation of C. suppressalis, and knockdown of CsCHS2 significantly affected growth during the larval stage, but had no significant effect on the pupation. Moreover, knockout of CsCHS1 by CRISPR/Cas9 genome editing severely lowered the hatching rate, larval survivorship, pupation rate, and eclosion rate, but only larval survivorship at the G0 generation was lowered after the knockout of CsCHS2. These results demonstrate that CsCHS1 and CsCHS2 play vital roles in the growth and development of C. suppressalis, and so have potential as insecticidal targets for the control of this highly damaging pest.