Search

Three winged morphs (parthenogenetic winged female, PWF; gynopara; and male) of the cotton-melon aphid Aphis gossypii Glover (Hemiptera: Aphididae) facilitate the migration and host transfer of this pest. However, host plants preferred by these three winged morphs and their released volatiles remain largely unclear. Herein, the summer host plants (Gossypium hirsutum and Brassica pekinensis) preferred by PWFs and the winter host plant (Prunella vulgaris) preferred by gynoparae and males were screened from 17 tested host plants. In addition, active components that elicited the electrophysiological responses of the antennae of three winged morphs were identified. Y-tube olfactometer bioassays showed that active volatile compounds such as dibutyl phthalate, cis-3-hexen-1-ol and a-pinene were significant attractants for three winged morphs. The identified olfactory active volatile compounds (OAVCs) were formulated at different ratios into 18 attractant formulae, of which 4 formulae exhibited desirable luring-enhancing effect on PWFs, gynoparae, and males. Styrene, cis-3-hexen-1-ol, a-pinene, and others were dominant ingredients. These four effective formulae were expected to develop environmentally friendly pesticides to control pests by blocking the migration of winged cotton aphids. Taken together, our findings provide research models for the development of new plant-derived green aphid control technologies based on the interactions between cotton aphid and host plants. [ABSTRACT FROM AUTHOR]

Understanding the population genetic structure and demographic dynamics of important agricultural pest insects is very important in studying insecticide resistance and control strategies. The plant bug Adelphocoris fasciaticollis (Reuter) (Hemiptera: Miridae) is one of the main insect pests on cotton in Northern China. We studied large-scale genetic structure and genetic diversity patterns and explored the demographic history. We also employed a phylogeographical approach on A. fasciaticollis samples using sequence data from mitochondrial DNA (mtDNA) and nuclear DNA (ncDNA). MtDNA showed a significant correlation between genetic and geographical distances, but ncDNA did not support this correlation. Both datasets revealed that A. fasciaticollis populations had experienced recent expansion and lacked a geographical structure. One reason for lack of a genetic structure is a high level of gene flow among the populations. We suggest that the strong flight capability of A. fasciaticollis has been aided by the East Asian monsoon and cold fronts to accelerate the rate of range expansion. In addition, decreased insecticide usage and disturbances from human activities may all have contributed to population expansion. The low effective population number was based on two datasets. It is suggested that the host crop use, local climate conditions, and the recent population expansion might be the main influencing factors. [ABSTRACT FROM AUTHOR]

The relationships between hosts and symbionts are complex and dynamic. Not only can symbionts significantly impact host phenotypes, but host interactions with symbionts may influence parasitoids. However, few studies to date have investigated the microbiomes of parasitized host offspring and considered the ecological implications of longitudinal microbiome dynamics. In this study, the parasitoid wasp Lysiphlebia japonica and its aphid host, Aphis gossypii, were used to examine the impact of parasitism on host offspring. Parental parasitism reduced the weight and reproductive capacity of the offspring; furthermore, the offspring showed reduced L. japonica parasitism rates. Moreover, the microbial composition of the parasitized and unparasitized aphid offspring were characterized with high-throughput 16S rRNA gene sequencing. This revealed that L. japonica parasitism strongly altered the microbial community in the offspring of parasitized aphids, particularly, the offspring of aphids parasitized for day 4. Overall, these results indicated that parasitoids can influence host--microbiome interactions by altering the microbiome of the host offspring. Our findings support the importance of further investigations into host--parasitoid--microbiome interactions. [ABSTRACT FROM AUTHOR]

Pardosa astrigera wolf spiders are important natural enemies of insect pests in cotton fields. Genetically modified (GM) crops expressing Bacillus thuringiensis (Bt) Cry proteins - toxic to target insect pests - are increasingly cultivated for insect pest management. To evaluate the potential negative effects of Bt-GM crops on beneficial non-target organisms, we assessed the effect of the Cry1Fa protein on P. astrigera, including on its symbiotic microbial communities. No adverse effects were detected on the survival rate and body weight of P. astrigera during growth and development. However, P. astrigera adult microbiome exhibited a reduced diversity as well as a shift in the microbial community structure. The dominant bacterial phyla in P. astrigera shifted from Actinobacteria to Firmicutes after feeding on prey enriched in Cry1Fa protein. Furthermore, Bacillus became the most abundant genus in P. astrigera females, while the dominant genus (Corynebacterium_1) in P. astrigera males did not change. Both males and females exhibited lower abundances of Wolbachia after feeding on Cry1Fa-contaminated prey. Overall, consuming Cry1Fa-contaminated prey changed the microbial community in P. astrigera, with higher impact in female microbiome. These findings provide new insights for environmental safety assessments of GM crops and to understand the importance of the potential effects of GM crops on microbiota of non-target organisms of importance for biocontrol ecosystem services. [ABSTRACT FROM AUTHOR]

Transgenic insect-resistant cotton expressing the Cry1Ac and/or CpTI protein has been released into the environment for commercial cultivation for over a decade in China. In this consecutive 3-year field study (2007-2009), we characterized the microbial populations in two different transgenic cotton fields and one non-transgenic cotton field to assess the environmental impact of long-term cultivation of transgenic insect-resistant plants in credible field conditions. We obtained samples at four different growth stages of cotton (seedling, budding, boll forming and boll opening). The results showed significant seasonal variation in the number of bacteria, fungi, azotobacter, denitrifying bacteria and ammonia-oxidizing bacteria and in diversity indices of microorganisms, but no significant difference in the number of each microbial population or diversity indices attributable to long-term cultivation of transgenic cotton. [ABSTRACT FROM AUTHOR]