摘要: RNA interference (RNAi) has developed rapidly as a potential green pest management strategy. At present, most studies have focused on the screening of aphid lethal genes, whereas only a few studies have been conducted on wing development, which is crucial for aphid migration and plant-virus dissemination. Here, the Myzus persicae genes vestigial (vg) and Ultrabithorax (Ubx) related to wing development, were cloned. These two genes were expressed in various tissues of 3rd-instar winged aphids. The mRNA level of vg was high in 3rd-instar nymphs, whereas the expression level of Ubx was high in adults. The nanocarrier-mediated delivery system delivered double-stranded RNAs for aphid RNAi using topical and root applications. The expression levels of vg and Ubx were downregulated by 44.0% and 36.5%, respectively, using the topical application. The simultaneous RNAi of the two target genes caused 63.3% and 32.2% wing aberration rates using topical and root applications, respectively. The current study provided a promising method for controlling aphid migration to alleviate the spread of insect transmitted plant diseases.

摘要: In moths, various enzymes, such as fatty acid synthases, fatty acyl desaturases, and fatty acyl reductases (FARs), are involved in pheromone biosynthesis. In particular, pheromone gland-specific FAR (pgFAR) plays an important role in converting the functional group from carboxylic to alcohol during pheromone biosynthesis. A novel pgFAR of Maruca vitrata, Mvi-pgFAR, was identified through transcriptome sequencing of its pheromone gland. To investigate the involvement of Mvi-pgFAR in pheromone biosynthesis, Mvi-pgFAR was cloned from the pheromone gland and suppressed by RNA interference (RNAi). Mvi-pgFAR harbored several conserved motifs related to NAD(P)H-binding, N-glycosylation, and adenosine / guanosine triphosphate binding. Phylogenetic analysis revealed that Mvi-pgFAR with other lepidopteran pgFARs formed an independent clade. Mvi-pgFAR was specifically expressed only in the pheromone gland. Quantitative real-time polymerase chain reaction showed that the diurnal expression levels of Mvi-pgFAR in the pheromone gland were the highest at 2 h before the scotophase. After primarily confirming Mvi-pgFAR suppression by RNAi, (E,E)-10,12-hexadecadienal (E10E12-16:Ald), a major sex pheromone component, was quantified by gas chromatography. When Mvi-pgFAR was successfully suppressed, E10E12-16:Ald production was reduced by up to half of that of the control, and the mating rate was subsequently decreased. Our results demonstrate that Mvi-pgFAR downregulation can suppress mating behavior by changing the relative sex pheromone component ratio, suggesting that Mvi-pgFAR can be used as a novel control target.

摘要: Sex-determination mechanisms evolve rapidly and vary between species. Occasionally, polymorphic systems are found, like in the housefly. Studying the dynamics and stability of such systems can provide a better understanding of the evolution of sex-determination systems. In the housefly, dominant male-determining loci (M) can lie not only on the Y chromosome (M-Y), but also on autosomes (M-A) or the X chromosome (M-X). M enforces male development by inhibiting the female-determining gene transformer (tra). A mutant tra allele, tra(D), is insensitive to M and is a dominant female determiner. M-Y prevails at high latitudes and polymorphic M loci together with tra(D) at low latitudes. To get more insight into the stability and frequencies of these sex determiners with mutually exclusive dominance, we investigated 5 regional Spanish populations. We found strong variation among populations. Two populations with hemizygous M-III were found, 2 contained homozygous M-X with additional hemizygous M-I and M-II in 1 population. One population contained homozygous and hemizygous M-X with additionally hemizygous M-II. All females in populations with homozygous M, had tra(D), whereas no tra(D) was found in populations without homozygous M. Our results indicate locally stable systems may either harbor a single hemizygous M and no tra(D), corresponding to a male heterogametic system, or homozygous and/or multiple M and heterozygous tra(D), reminiscent of a female heterogametic system. They support that M loci can accumulate in the presence of a dominant female determiner. Limited migration between populations may contribute to the stability of these systems.

摘要: Color polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. We explored the color morph diversity and composition in a Chrysomela lapponica leaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species. We obtained information on 13 617 specimens of this beetle from museums, private collections, and websites. These specimens (collected from 1830-2020) originated from 959 localities spanning 33 degrees latitude, 178 degrees longitude, and 4200 m altitude. We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism (quantified by the Shannon diversity index) and in the relative frequencies of individual color morphs. The highest level of polymorphism was found at high latitudes and altitudes. The color morphs differed in their climatic requirements; composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year, longitude, mean July temperature and between-year temperature fluctuations. The proportion of melanic beetles, in line with the thermal melanism hypothesis, increased with increasing latitude and altitude and decreased with increasing climate seasonality. Melanic morph frequencies also declined during the past century, but only at high latitudes and altitudes where recent climate warming was especially strong. The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments, presumably due to the different climatic requirements of coexisting color morphs.

摘要: The fall armyworm Spodoptera frugiperda is a worldwide serious agricultural pest, and recently invaded South China. Sex pheromone can be employed to monitor its population dynamics accurately in the field. However, the pheromone components previously reported by testing different geographic populations and strains are not consistent. On the basis of confirming that the S. frugiperda population from Yunnan Province belonged to the corn strain, we analyzed the potential sex pheromone components in the pheromone gland extracts of females using gas chromatography coupled with electroantennographic detection (GC-EAD), gas chromatography coupled with mass spectrometry (GC-MS) and electroantennography (EAG). The results show that (Z)-9-tetradecenal acetate (Z9-14:Ac), (Z)-11-hexadecenyl acetate (Z11-16:Ac), (Z)-7-dodecenyl acetate (Z7-12:Ac) or (E)-7-dodecenyl acetate (E7-12:Ac) with a ratio of 100 : 15.8 : 3.9 induced EAD responses to varying degrees: Z9-14:Ac elicited a strong EAD response, Z7-12:Ac or E7-12:Ac elicited a small but clear EAD response, while Z11-16:Ac elicited a weak EAD response. Further single sensillum recording (SSR) showed that Z9-14:Ac and Z7-12:Ac induced dose-dependent activities in two types (A and B) of sensilla in male antennae, respectively, while the sensilla in response to E7-12:Ac and Z11-16:Ac was not recorded. Finally, wind tunnel tests reveal that Z9-14:Ac and Z7-12:Ac are two principal sex pheromone components of the tested population.