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Background Apolygus lucorum is a worldwide omnivorous pest damaging a range of crops and causing great economic losses. Symbiotic bacteria living in insects play a key role in the nutrition, physiology, and behavior of hosts. Here, we present an experiment using Illumina HiSeq sequencing targeting the V3–V4 regions of bacteria’s 16S rRNA throughout the entire life cycle of A. lucorum. Results The first and second instar nymphs have the largest alpha diversity compared with other life stages of the insect. Bacterial phyla Proteobacteria (72.29%), Firmicutes (15.24%), Actinobacteria (7.76%) exhibit the largest relative abundance in all developmental stages. Erwinia (23.97%) and Lactococcus (10.62%) are the two genera with the highest relative abundance. The relative abundance of Erwinia in the nymph stage is significantly greater than the adult stage, and the relative abundance of Lactococcus in 6-day-old and 9-day-old adult females is higher compared with adult males. Conclusions These results reveal that microbial community composition and relative abundance shift dynamically at different life stages, implying that different bacterial phyla and genera may have specific roles in specific life stages such as metabolism, nutrition absorption, detoxification, and reproduction. This study reveals for the first time the community composition and ecological dynamics of symbiotic bacteria throughout the life stages of A. lucorum, and thus may provide insight to new strategies for pest control.

Background Aphis gossypii Glover (Hemiptera: Aphididae), a worldwide polyphagous phloem-feeding agricultural pest, has three wing morphs (winged parthenogenetic female, gynopara, and male) in the life cycle. The exclusive males could fly from summer hosts to winter hosts, which are essential for gene exchanges of cotton aphid populations from different hosts or regions. However, the molecular mechanism of wing differentiation of male in A. gossypii remains unclear. Results Morphological observation of male A. gossypii showed that there is no distinct difference in the external morphologies of the 1st and 2nd instar nymphs. The obvious differentiation of wing buds started in the 3rd instar nymph and was visible via naked eyes in the 4th instar nymphal stage, then adult male emerged with full wings. According to morphological dynamic changes, the development of wings in males were divided into four stages: preliminary stage (the 1st instar to 2nd instar), prophase (the 3rd instar), metaphase (the 4th instar), anaphase (the 5th instar). Results of feeding behavior monitoring via EPG (electrical penetration graph) technology indicated that although the male cotton aphids had strong desire to feed (longer duration of C 55.24%, F 5.05% and Pd waves 2.56%), its feeding efficiency to summer host cotton was low (shorter E1 3.56% and E2 waves 2.63%). Dynamic transcriptome analysis of male aphid at 5 different developmental periods showed that in the 3rd instar nymph, the number of up-regulated DEGs was significant increased, and time-course gene transcriptional pattern analyses results also showed that numerous genes categorized in clusters 3, 5, and 8 had the highest expressed levels, which were consistent with morphological changes of wing buds. These results indicate that the 3rd instar nymph is the critical stage of wing bud differentiation in males. Furthermore, through pathway enrichment analysis of DEGs and WGCNA, it revealed that the neuroactive ligand-receptor interaction, Ras signaling pathway, dopaminergic synapse, circadian entrainment and the corresponding hub genes of PLK1, BUB1, SMC2, TUBG, ASPM, the kinesin family members (KIF23, KIF20, KIF18-19) and the novel subfamily of serine/threonine (Aurora kinase A and Aurora kinase B) probably played an important role in the critical stage of wing bud differentiation. Conclusion This study explored morphological changes and genes transcriptional dynamics males in cotton aphid, revealed the phenomenon of low feeding efficiency of winged males on summer host cotton, and identified key signaling pathways and potential hub genes potentially involved in wing bud differentiation of male in A. gossypii.

Background Cotton (Gossypium spp.) is one of the most important economic crops worldwide, and its production plays an important role in the economy of many countries. Genetically modified herbicide-tolerant (GMHT) crops, which were developed to minimize the losses caused by weeds, have gradually become the most widely adopted genetically modified crops in the world due to their economic and environmental benefits. However, the potential ecological and environmental risks of GMHT crops have attracted extensive attention and controversy. Arthropod communities form a prominent part of the biodiversity of agroecosystems and are important indicators of environmental health. Elucidating the effects of GMHT crops on the diversity of arthropod communities is necessary to ensure the safety of GMHT crops. Result In this 2-year study, we investigated the potential impact of GMHT crops on arthropod communities. The GMHT cotton variety GGK2 with glyphosate tolerance and its near-isogenic non-GMHT variety K312 were used for the experimental groups. The Shannon diversity index (H), Simpson diversity index (D), Pielou evenness index (J), and principal co-ordinates analysis (PCoA) of the Bray–Curtis distance were used to evaluate the population dynamics and biodiversity of arthropods in cotton fields. No significant differences were found between GGK2 and K312 in their total abundance of arthropod communities, and biodiversity indexes on most sampling dates. The arthropod composition in the GGK2 and K312 plots was similar. Sampling dates had a significant effect on biodiversity indexes, whereas no clear tendencies related to cotton variety or cotton variety × sampling dates interaction were recorded. In addition, PCoA revealed high similarity between the arthropod communities in the plots of the GMHT cotton variety GGK2 and its near-isogenic variety K312. Conclusion There was no obvious difference in abundance, diversity indexes of arthropod communities between GMHT cotton variety GGK2 and its near-isogenic variety K312 under the small-scale planting regime.

Research on feature selection in text classification is usually limited to propose various techniques to select a set of features with highest scores based on different metrics. The selected features are usually determined by using a separate validation dataset with a fixed threshold. Obviously, it may not generalize well to new data as the best number for selected features is various on different datasets. In this paper, we first conduct a deep analysis, and find that simply extracting the features based on the score calculated by a metric may not always be the best strategy as it may turn many documents into zero length, which make them not suitable for training. We then model the feature selection process as a multiple objectives optimization problem to gain the best number of selected features rationally and automatically. In addition, as the optimization process costs a lot of resources, we design a parallel algorithm to improve the running time using dynamic programming. Extensive experiments are performed on several popular datasets, and the results indicate that our proposed approach is effective and feasible.

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.