【Aim】 Toll receptors of Toll signaling pathway, an important immune signaling pathway of insects, are essential to maintain immune response against invading exogenous microorganisms in insects. This study aims to explore the influence of peptidoglycan (PGN) and Staphylococcus aureus on the expression of the Toll receptor genes BmToll9-1 and BmToll9-2 in the silkworm, Bombyx mori. 【Methods】 PGN, the main component in cell wall of Gram-positive bacteria, and a Gram-positive bacterium S. aureus were respectively injected into the day-1 5th instar larvae of B. mori to induce the immune response. The relative expression levels of BmToll9-2 and BmToll9-1 in the midgut, epidermis, fat body and silk glands of the larvae at different time points post injection were detected by real-time quantitative PCR. 【Results】 After injection of PGN or S. aureus into the 5th instar larvae of B. mori, BmToll9-2 was differentially expressed at different time points and in different tissues. Injection of PGN or S. aureus induced up-regulation of the expression of BmToll9-2 in the midgut of the 5th instar larvae, achieving the best induction effect at 3 and 6 h post injection, respectively, and the induction effect of S. aureus was better than that of PGN. Injection of S. aureus induced up-regulation of the expression of BmToll9-2 in the epidermis, fat body and silk glands of the 5th instar larvae, achieving the best induction effects at 24, 6, and 24 h post injection, respectively. Injection of S. aureus also induced up-regulation of the expression of the homogenous BmToll9-1. 【Conclusion】 The expression of BmToll9 genes in different tissues of B. mori larvae is up-regulated after injection of PGN or S. aureus, suggesting that BmToll9 genes are involved in the immune response of B. mori against PGN and S. aureus.

Pollination is a very important link in natural ecosystem, and it is also a key step related with the yield in agricultural ecosystem. As well known, hymenopterans are the most important pollinating insects. In fact, dipterans are also important pollinators due to the advantages of wide distribution, diverse richness, and enormous abundance. Yet the pollination by dipterans has not been paid enough attention. In this article we mainly summarized the main dipteran pollinators, the pollination effectiveness and pollination features of dipteran insects as pollinators, their coevolution with plants, and the ecological meaning of pollination by dipteran insects. It is recorded that at least 71 families of Diptera are involved in entomophily, and new evidence indicates that there are about 54 417 species of Diptera among flower-visiting insects, ranking the 4th in the orders of Insecta involved in entomophily based on the number of species involved. Although dipteran insects carry relatively less pollen on a single visit (compared to Hymenoptera), high visitation rate and enormous individuals ensure their position as effective pollinators. Pollination syndromes can effectively reveal the co-evolutionary relationship between plants and pollinators. Especially in recent years, the in-depth study of specialized pollination (e. g. Schisandraceae and midge system) and generalized pollination has deepened our understanding of coevolution. In terms of ecological meaning of pollination, on the one hand, dipteran insects are beneficial supplement to Hymenoptera, and on the other hand, in some special environments dipteran insects can play an irreplaceable role. At present the number of pollinating insects (including Diptera) has declined sharply, while the pollination value of dipteran insects is still less utilized. According to the current research situation in China, we put forward the following aspects as the future research focus: i) deepening case studies on the effectiveness and adaptability of dipteran insects as pollinators in order to determine the position of dipteran insects in pollination system; ii) strengthening the studies on habitat pattern change and insect diversity in order to clarify the impact of habitat change on insects; iii) sorting the relationship between flower-visiting and pollination, specialized pollination and generalized pollination in order to clarify the role of dipteran insects in the co-evolution with plants; and iv) gradually deepening the investigation of pollen waste and pollen competition in order to explore pollination strategies and plant reproductive strategies. All these efforts will be helpful for knowledge popularization, conservation and further utilization of Diptera as a pollinating group.