This review investigates ant–aphid mutualism (trophobiosis), in particular focusing on evolutionary processes in aphids resulting from this interaction. This broad literature review allows us to revise existing views on certain aspects of this mutualism and provide the first timeline of its possible development over a geological timescale. We propose a new classification of ant–aphid mutualism with respect to its ecological characteristics and present new explanations of the development of certain morphological structures of aphids as resulting from adaptation to a trophobiotic relationship with ants. In light of these findings, the presence of the so‐called ‘trophobiotic organ’ in all myrmecophilous aphids is questioned. We review various communication modes between aphids and mutualistic ants and the possible influence of this symbiosis on modifications of aphid life cycles. Recent evidence on the suspected role of endosymbiotic bacteria in the development of mutualism is discussed. Finally, we propose a first timeline of ant–aphid interactions leading to the development of particular adaptations of aphids to mutualism, from general interactions between diverging Aphidomorpha and ants in the late Mesozoic to more specific coevolution between the aphid tribe Fordini and the ant genus Lasius.
The study presents new data on the morphology and distribution of the labial tip sensilla of six species of two nabid subfamilies-Protosteminae and Nabinae (Heteroptera: Cimicomorpha), which were obtained using a scanning electron microscope. In both taxa, there are five morphologically distinct types of sensilla on the tip of the labium: peg sensilla with a terminal pore, nonporous peg sensilla, elongated placoid sensilla with wall pores (multiporous), and trichoid sensilla. In addition, oval plate sensilla with a terminal pore (Tp-opls) were observed in the genus Himacerus. Campaniform sensilla and nonporous chaetic sensilla were observed on the surface of the last segment of the labium in all of the studied species. Over a dozen trichoid sensilla were scattered on the last segment of the labium only in the genus Prostemma. Based on their external structure, it is likely that these sensilla are chemosensitive and mechanosensitive. The oval plate sensilla with a Tp-opls (gustatory) in Himacerus (Nabinae) represent a morphological novelty that probably evolved independently of other nabids.
Termination of the life cycle of sexually reproducing aphids usually takes place in autumn, during October and November, in the climatic conditions of Central Europe. However, episodes of warm weather are suspected to trigger prolongation of the life cycle. Observations of Stomaphis spp. in early winter of 2013/2014 in southern Poland support this thesis. Surprisingly, adult females of two species were collected as late as early January and early March. High daily temperatures during this period were the probable cause of aphid survival, despite frosty nights. The possibility of the influence of warm weather episodes (higher temperature) on prolongation of the life cycle in aphids, or such episodes causing permanent parthenogenesis, is discussed.
New data on distribution, biology, and ecology of some little-known cerambycid species, collected in the western part of Tajikistan, are presented. Arhopalus rusticus (Linnaeus, 1758) is recorded in Tajikistan for the first time. New localities of species considered pests or invasive species such as Aeolesthes sarta (Solsky, 1871) and Xylotrechus stebbingi Gahan, 1906 are also given. The list of the taxa collected by the first author during many years of field research in Tajikistan as well as photographs of poorly known species from his collection, including some endemics, are additionally provided. Furthermore, high quality photographs of some extremely rare species that were collected during our expedition, i.e., Turkaromia gromenkoi Danilevsky, 2000 and Ropalopus nadari Pic, 1894, with images of their habitats or feeding grounds are also presented for the first time.
Firm matching of genitals during copulation is of critical importance to effective insemination and thus, gene flow. During the evolution of insects, an effective position during copulation promoted higher fecundity through control over the act of mating or elimination of competitors. Usually during insect copulation, either twisting or flexing of the male abdomen occurs, and genitals remain symmetrically or asymmetrically disposed following changes in the mating position. However, it is always the dorsal side of the male genitalia that makes contact with the ventral side of female abdomen. Here we present the unusual case of a ‘belly-to-belly’ copulation, with symmetrically positioned male genitals and no twisting of the abdomen. During the mating of two species in the Stomaphis genus of large, tree dwelling aphids, the dwarfish male is attached to the underside of the female, with the ventral part of its genitals contacting the ventral part of female abdomen, and the aedeagus effectively inserted into the female genital organs. Interestingly, congeneric species do not exhibit this sort of mating, but differences in the genital plates of females, between species, may play an important role. These observations raise many questions concerning the possible dominant role of the female during mating and later, during mate guarding by male, which can lead to monandry in this generally polyandrous group of insects. It is possible that this sort of mating is either an adaptation to the competitive behaviour of other males or a consequence of the obligatory mutualistic relationship with ants, and the adaptation to specialised ecological niches enforced by this relationship. If ants do influence the mating habits of Stomaphis then it is possible that speciation in this group of insects, and phytophagous insects generally, is partially driven by their relationship with ants.
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