Search

Simple Summary: The rice leaf-roller Cnaphalocrocis medinalis is a migratory pest of rice. Monitoring its population is important in integrated pest management systems. Trapping them with a sex pheromone or plant odor has been used in population monitoring. We studied the physiological status of adults trapped by sex pheromones and floral odors. In the immigrant group, the number of males caught in the floral trap was greater than those caught by the sex pheromone trap. The volumes of testes in adults caught using the above two trapping methods were similar. In the local breeding group, the number of males caught by sex pheromone trapping was greater than that by floral trapping. The volume of testes was smaller in males caught in the floral odor trap compared to the pheromone trap. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The number of eggs laid by the females in the local breeding group was greater in those caught in the sweep net in comparison with those caught in the floral odor trap. The rice leaf-roller Cnaphalocrocis medinalis is an important migratory pest of rice. We conducted a study to determine the physiological status of adults trapped by a sex pheromone and floral odor. In the immigrant group, the number of males trapped by the floral odor was greater than the number caught by sex pheromone trapping. The volume of testes was similar in the above two trapping methods but was smaller than in the sweep net method. The ovary developmental grade, mating rate, and number of matings of females caught in floral odor trap were higher than in those caught in the sweep net. In the local breeding group, the number of males trapped by sex pheromones was greater than the number trapped by the floral odor. The volume of testes was smaller in the floral odor trap compared to the pheromone trap group, with the largest in the sweep net group. The ovarian developmental grade, mating rate, and number of matings of females were significantly higher in the floral odor trap group than in the sweep net group. In the emigrant group, the adult olfactory response to the sex pheromone and floral odor was low. The volume of testes was larger in the sweep net group compared to the moths caught by floral odor trapping. The number of eggs laid by female immigrants trapped by the floral odor and sweep net was similar, while the number in the local breeding group was greater in moths caught with the sweep net in comparison with those caught by the floral odor trap. The difference in egg hatchability between the two trapping methods in both immigrants and local breedings was not significant. [ABSTRACT FROM AUTHOR]

Premating behaviors mediated by pheromones play pivotal roles in animal mating choices. In natural populations of the striped stem borer Chilo suppressalis and the rice leaf roller Cnaphalocrocis medinalis in the rice field habitat, we discovered that Z11‐16:Ald, a major component of the C. suppressalis pheromone, modulated the premating behavior of C. medinalis. Z11‐16:Ald evoked a strong olfactory response in male antennae and strongly inhibited the sex pheromone trapping of male C. medinalis in the field. The functions of three C. medinalis sex pheromone receptor genes (CmedPR1–3) were verified through heterologous expression in Xenopus oocytes. CmedPR1 responded to Z11‐18:OH and Z11‐18:Ald, as well as the interspecific pheromone compound Z11‐16:Ac of sympatric species; CmedPR2 responded to Z13‐18:OH and Z13‐18:Ald, as well as the sex pheromone compounds Z11‐16:Ald and Z9‐16:Ald of sympatric species; and CmedPR3 responded to Z11‐18:OH and Z13‐18:OH, as well as the interspecific pheromones Z11‐16:OH, Z9‐16:Ald, Z11‐16:Ac, and Z11‐16:Ald of sympatric species. Thus, CmedPR2 and CmedPR3 share the ligand Z11‐16:Ald, which is not a component of the C. medinalis sex pheromone. Therefore, the sex pheromones of interspecific species affected the input of neural signals by stimulating the sex pheromone receptors on the antennae of male C. medinalis moths, thereby inhibiting the olfactory responses of the male moths to the sex pheromones. Our results demonstrate chemical communication among sympatric species in the rice field habitat, the recognition of intra‐ and interspecific sex pheromones by olfactory receptors, and how insect premating behaviors are modulated to possibly affect resource partitioning. [ABSTRACT FROM AUTHOR]

Glyphodes pyloalis (Lepidoptera, Crambidae) is an important pest of mulberry trees in China, and current methods for accurate population monitoring and control of this pest are lacking. The sex pheromone of G. pyloalis in China was re‐identified as E10, E12, Z14‐hexadecenyl acetate (E10E12Z14‐16:Ac) and tentatively E10, E12, E14‐hexadecenyl acetate (E10E12E14‐16:Ac). The emergence began 2 h before the dark period, and the peak emergence was 3 h into scotophase. Analysing the female moth's age from 1–9 days revealed that the titre of sex pheromone E10E12Z14‐16:Ac and E10E12E14‐16:Ac did not change statistically, and the ratio remained constant at 7.19 ± 1.12. The titre of pheromone had a significant circadian rhythm, increasing at 2 h after darkness, peaking at 6–8 h before decreasing, but it was still detected after 4 h into photophase. Mating of G. pyloalis occurred mainly at night, with the highest rate during 3 h into scotophase, which was earlier than the temporal pattern of pheromone titres. 18.1% of unfed moths mated immediately after eclosion during the scotophase. This was lower than what is seen in 1–3‐day‐old moths but similar to 4‐day‐old moth. Mating can occur on the same day after emergence, primarily within 1–4 days. Female moths can release pheromone again 48 h after mating, but the ratio of E10E12Z14‐16:Ac and E10E12E14‐16:Ac was reduced to 5.1 ± 0.73. The trapping of male moths in the field showed a significant circadian rhythm, but significant differences in pheromone trapping in Sichuan Gongxian, Zhejiang Chun'an and Haining, and Jiangsu Wujiang were observed. At the same location, the circadian rhythm of moth trapping showed differences between generations. The trapping of the overwintering generation occurred mostly in the early period of scotophase, while other generations were caught slightly later. Our results contribute to effective pheromone trapping for monitoring and mass trapping to better control G. pyloalis populations. [ABSTRACT FROM AUTHOR]

The piercing fruit moth Oraesia emarginata is an economically significant pest; however, our understanding of its olfactory mechanisms in infestation is limited. The present study conducted antennal transcriptome analysis of olfactory genes using real-time quantitative reverse transcription PCR analysis (RT-qPCR). We identified a total of 104 candidate chemosensory genes from several gene families, including 35 olfactory receptors (ORs), 41 odorant-binding proteins, 20 chemosensory proteins, 6 ionotropic receptors, and 2 sensory neuron membrane proteins. Seven candidate pheromone receptors (PRs) and 3 candidate pheromone-binding proteins (PBPs) for sex pheromone recognition were found. OemaOR29 and OemaPBP1 had the highest fragments per kb per million fragments (FPKM) values in all ORs and OBPs, respectively. Eighteen olfactory genes were upregulated in females, including 5 candidate PRs, and 20 olfactory genes were upregulated in males, including 2 candidate PRs (OemaOR29 and 4) and 2 PBPs (OemaPBP1 and 3). These genes may have roles in mediating sex-specific behaviors. Most candidate olfactory genes of sex pheromone recognition (except OemaOR29 and OemaPBP3) in O. emarginata were not clustered with those of studied noctuid species (type I pheromone). In addition, OemaOR29 was belonged to cluster PRIII, which comprise proteins that recognize type II pheromones instead of type I pheromones. The structure and function of olfactory genes that encode sex pheromones in O. emarginata might thus differ from those of other studied noctuids. The findings of the present study may help explain the molecular mechanism underlying olfaction and the evolution of olfactory genes encoding sex pheromones in O. emarginata. [ABSTRACT FROM AUTHOR]