An in-depth study of the larval head skeleton and the external feeding structures related with the ingestion of food particles by the eristaline flower flies Eristalis tenax and Eristalinus aeneus

There is an important lack of knowledge regarding the mechanisms and morphology of the structures involved in the feeding process of the bee-mimicking eristaline flower fly species (Diptera: Syrphidae). In order to look more deeply into their larval feeding biology, a morphological study of the head skeleton and the external feeding structures of the three larval instars of Eristalis tenax (L.) and Eristalinus aeneus (Scopoli), important pollinators and bioindicators of water quality, was carried out, using scanning electron microscopy and confocal laser scanning microscopy. Additionally, an analysis of the ingested particle size was conducted, using various pollen grains and fungal spores. The main differences, found between the third instars of both species, consisted of the more restrictive mandibular lobes of E. tenax, which prevent the ingestion of bigger particles, and a wider filtering area in the cibarium of E. aeneus, which increases the number of particles that can be retained and ingested. Eristalinus aeneus is able to ingest bigger particles (80–100 μm) than E. tenax (70–80 μm). These results suggest that the structures involved in the feeding process of E. aeneus are less restrictive, thus increasing its survival chances when, under artificial rearing conditions, the same medium is used for both species. This study may contribute to the improvement in artificial rearing for future studies on pollination and decomposition.     

Forests are critically important to global pollinator diversity and enhance pollination in adjacent crops

Although the importance of natural habitats to pollinator diversity is widely recognized, the value of forests to pollinating insects has been largely overlooked in many parts of the world. In this review, we (i) establish the importance of forests to global pollinator diversity, (ii) explore the relationship between forest cover and pollinator diversity in mixed-use landscapes, and (iii) highlight the contributions of forest-associated pollinators to pollination in adjacent crops. The literature shows unambiguously that native forests support a large number of forest-dependent species and are thus critically important to global pollinator diversity. Many pollinator taxa require or benefit greatly from resources that are restricted to forests, such as floral resources provided by forest plants (including wind-pollinated trees), dead wood for nesting, tree resins, and various non-floral sugar sources (e.g. honeydew). Although landscape-scale studies generally support the conclusion that forests enhance pollinator diversity, findings are often complicated by spatial scale, focal taxa, landscape context, temporal context, forest type, disturbance history, and external stressors. While some forest loss can be beneficial to pollinators by enhancing habitat complementarity, too much can result in the near-elimination of forest-associated species. There is strong evidence from studies of multiple crop types that forest cover can substantially increase yields in adjacent habitats, at least within the foraging ranges of the pollinators involved. The literature also suggests that forests may have enhanced importance to pollinators in the future given their role in mitigating the negative effects of pesticides and climate change. Many questions remain about the amount and configuration of forest cover required to promote the diversity of forest-associated pollinators and their services within forests and in neighbouring habitats. However, it is clear from the current body of knowledge that any effort to preserve native woody habitats, including the protection of individual trees, will benefit pollinating insects and help maintain the critical services they provide.     

中国优食蚜蝇属六新种记述(双翅目:食蚜蝇科)

本文记述我国优食蚜蝇属Eupeodes(syn.Metasyrphus)6新种。属下分类采取Vockeroth(1969,1986)的分亚属概念。文中记述的新种全部属于优食蚜蝇亚属Eupeodes(s.str.),并将本亚属内其他5种食蚜蝇重新组合,同时对有些种的中名也作了相应修改。新种模式标本保存于上海农学院。 新组合种:1.硕翅优食蚜蝇Eupeodes(Eupeodes)macropterus(Thomson),1869