Winged Individuals Research Articles

An Aphid Pest Superclone Benefits From a Facultative Bacterial Endosymbiont in a Host-Dependent Manner, Leading to Reproductive and Proteomic Changes.

The English grain aphid, Sitobion avenae, is a significant agricultural pest affecting wheat, barley, and oats. In Chile, the most prevalent and persistent clone (superclone) of S. avenae harbors the facultative endosymbiont bacterium Regiella insecticola. To determine the role of this bacterium in the reproductive success of this superclone, the presence of R. insecticola was manipulated to assess its impact on (1) the reproductive performance of this clone on two host plant species (wheat and barley), (2) the production of winged morphs, (3) changes in the insects' proteomic profiles, and (4) the root/shoot ratio of plant. It was found that the reproductive performance of this S. avenae superclone varied across host plants, depending on the presence of the facultative bacterial endosymbiont. Aphids infected with R. insecticola showed higher reproductive success on wheat, while the opposite effect was observed on barley. Aphid biomass was greater when infected with R. insecticola, particularly on barley. Additionally, aphids harboring R. insecticola exhibited a higher proportion of winged individuals on both host plants. Protein regulation in aphids on wheat was lower compared to those on barley. A higher root/shoot biomass ratio was observed in wheat plants compared to barley when infested by R. insecticola-infected aphid. Thus, R. insecticola significantly influences the reproductive performance and proteomic profile of a S. avenae superclone, with these effects shaped by the host plant. This suggests that the interaction between the host plant and the facultative endosymbiont contributes to the ecological success of this superclone.

Repellent Effects of Coconut Fatty Acid Methyl Esters and Their Blends with Bioactive Volatiles on Winged Myzus persicae (Sulzer) Aphids (Hemiptera: Aphididae).

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most important aphid crop pests, due to its direct damage and its ability to transmit viral diseases in crops. The objective is to test whether spraying nanoemulsions of botanical products repels winged individuals of M. persicae in a bioassay in culture chambers. The bioactive volatiles were applied on pepper plants at a dose of 0.2% alone or at 0.1% of each component in blends. A treated plant and a control plant were placed at each side of an entomological cage inside a growth chamber. The winged individuals were released between the plants, in a black-painted Petri dish suspended by wires in the upper half of the cage. The most repellent products were farnesol (repellency index, RI = 40.24%), (E)-anethole (RI = 30.85%) and coconut fatty acid methyl ester (coconut FAME) (RI = 28.93%), alone or in the following blends: farnesol + (E)-anethole + distilled lemon oil (RI = 36.55%) or (E)-anethole + distilled lemon oil + coconut FAME (RI = 30.63%). The observed effect of coconut FAME on aphids is the first report of this product having a repellent effect on a crop pest. Repellent substances for viral disease vectors should be further investigated to develop new strategies for plant protection.

Results of monitoring winged aphids (Hemiptera: Aphididae) on potato plantations in the conditions of the Northern region of Russia

The studies were carried out in the conditions of the northern part of the Arkhangelsk region in the period 2017-2021. The purpose of the research is to determine the abundance and species composition during the annual monitoring of the flight of winged aphids on potato plantations, to establish patterns of insect migration. To catch winged individuals, yellow water traps were used, installed along the perimeter of the field at the beginning of the potato germination phase. The last extraction of the catch was carried out after the desiccation of the potato tops. As a result of the monitoring, 22 species of winged aphids were identified. Of the total number, direct and potential vectors of viruses are represented by 6 species ‒ Acyrthosiphum pisum Harr., Aphis fabae Scop., Aphis nasturtii Kalt., Aulacorthum solani Kalt., Hyperomyzus lactucae L., Rhopalosiphum padi L., their share in the abundance structure ranged from 69.8 to 91.7 %. From the group of aphids-carriers of viruses, 5 species annually migrate to plantings: A. corni F., A. fabae Scop., A. nasturtii Kalt., A. solani Kalt., R. padi L. The total number of winged aphids ranged from 61 individuals in 2020 to 107 individuals in 2018, and in 2021 there was an outbreak of mass reproduction R. padi L. and A. fabae Scop., which increased the total number of captured winged aphids to 1778 individuals. In the period from 2017 to 2020, the prevalence of virus vectors corresponded to a low value (16-27 individuals per 1 water trap), in 2021, against the background of an outbreak of mass reproduction, the prevalence of virus vectors increased to an average value (445 winged individuals per 1 water trap during the growing season). The accumulation of a large migratory potential of aphids occurs under favorable weather conditions in the winter and spring periods, and also, if possible, feed on the primary food plant for a long time. If the host plant is unsuitable for feeding, aphids migrate in search of food, as a result of which their number decreases.

Homeopathic solutions induce production of winged forms in aphid

The aphids control (Brevicoryne brassicae L.) in kale (Brassica oleracea L. var. acephala) is one of the main challenges for its production. This obstacle becomes greater in agroecological production systems. Thus, the objective of this study was to verify the formation of winged individuals in colonies of B. brassicae aphids, when exposed to kale treated with homeopathic solutions. The treatments were resistant 5CH, susceptible attacked 5CH, aphid nosode 30CH, and the controls that are water (without dynamization) and distilled water + 70% ethanol 5CH, being applied every day for 15 days. Kale plants were inoculated with aphids and irrigated using homeopathic solutions. After 15 days of inoculation, the plants were removed from the bag and the number of winged forms and nymphs of B. brassicae was counted. Homeopathic preparation Resistant 5CH provided a smaller number of winged individuals and a larger number of nymphs per colony. The plants treated with the susceptible attacked 5CH homeopathy showed a higher number of winged aphids, but a reduced number of nymphs. Aphid nosode 30CH treatment was promising to Brevicoryne brassicae control in kale plants, as it induced polymorphism, presenting a greater number of winged aphids and a reduced number of nymphs per colony.

Фотопериодическая регуляция образования крылатых форм у свекловичной тли (Aphis fabae Scopoli, 1763)

The study of the process of migration in aphids has great practical importance. Thus, the aphids pass from one plant to another by these morphs and feed there and maintain their population by growing. The literature information on the research of the photoperiodic reactions in aphids is sufficient. However, the seasonal adaptation characteristics of sugar beet aphids have not been studied up to date in Azerbaijan. For this reason, the study of an impact of photoperiod on the emergence of winged ones in the population of black bean aphid is one of the important issues. During the study of reaction of individuals fed in the same routine against the photoperiod in the next generations, it has been defined that short photoperiod is more observed in the following generations. It seems that the information collected from the former generations is directly passed to the next generations. The results show that the continuous breeding of these species by means of parthenogenesis is only available in the long day (14, 16, 18, 24 hours) routine. However, the winged individuals prevail in the short photoperiods. The preference of winged individuals in 24 hours of photoperiod rather than others (14–18 hours) is probably related to the physiological changes occurs in them.

Aphid Survey Reveals the First Record of the Bramble Aphid Aphis ruborum (Börner & Schilder, 1931) (Hemiptera: Aphididae) in Algeria, and a Second Report for Africa After 59 Years

Since aphids are considered among the most dangerous pests to crops, it is important to know the species existing in a given biotope. The results showed a total richness of 48 aphid species, divided into 29 genera, six tribes and four subfamilies. Aphis fabae, Aphis gossypii and Myzus persicae are the most captured species with 14.74 %, 11.96 % and 9 % respectively. This paper presents the first finding of Aphis ruborum (Börner & Schilder, 1931) (Hemiptera: Aphididae) for Algeria and the second record for the African continent. This aphid is reported for the first time from the Tizi-Ouzou province. The first winged individuals were caught in yellow traps installed in a potato field in Makouda (Tizi-Ouzou, northern Algeria). Several colonies were detected on wild brambles around this field. Two aphid species are found on potato leaves, namely M. persicae and A. fabae. M. persicae was the most abundant species with 1082 individuals.

Previous herbivory modulates aphid population growth and plant defense responses in a non-model plant, Carthamus tinctorius (Asteraceae).

Plants have a variety of defense mechanisms that are often induced following attacks by herbivores; this benefits those plants by decreasing performance or preference of herbivores that attack the plants later. We investigated the effects of previous exposure of plants to the safflower aphid, Uroleucon carthami, cotton bollworm, Helicoverpa armigera, and mechanical wounding on subsequent safflower aphid infestations using commercial safflower (Carthamus tinctorius) cultivars and wild safflower species (C. oxyacantha). The experiments were conducted in a greenhouse with two treatments: previously induced plants via direct herbivory or mechanical wounding, and control plants that had never experienced herbivory. To test the performance of safflower aphid on different plant treatments, five unwinged aphids were placed on each plant and allowed to reproduce for 14 days. Finally, the total numbers of aphids on each plant were counted and the percentage of produced winged individuals was calculated. The number of aphids on plants that were previously infested or injured was significantly lower than in control plants. Percentage of winged aphids was significantly higher on induced plants, which is an indicator for unsuitable conditions. Also, significant increase in total phenolic content and hydrogen peroxide was observed in induced plants, showing that the levels of these compounds were either treatment, cultivar and/or genotype × treatment dependent, highlighting the specificity of these interactions. Overall, among the safflower cultivars the lowest number of aphids and the highest percentage of winged aphid individuals were observed on Mahali-Isfahan cultivar and wild safflower, showing that this cultivar is more sensitive to herbivory and/or responds to it more than other cultivars. These findings could contribute to a better utilization of induced defense in the integrated pest management of safflower fields.

Genetic diversity in a restricted-dispersal kissing bug: The centre-periphery hypothesis halfway.

The centre-periphery hypothesis (CPH) postulates that populations close to the centre of a species distribution will exhibit higher genetic diversity and lower genetic differentiation than populations located at the edge of the distribution. The centre of a species' distribution might represent an optimum for the environmental factors influencing the species absolute fitness and, therefore, genetic diversity. In species with wide distribution, the geographical variation of biotic and abiotic variables is crucial to understand the underlying mechanisms of the CPH. We evaluated the CPH and specifically tested which environmental variables better explained the patterns of genetic diversity in the kissing bug Mepraia spinolai, one of the main wild vectors of Chagas disease in southern South America, distributed across three Mediterranean climatic ecoregions in Chile. We analysed 2380 neutral single nucleotide polymorphisms to estimate genetic diversity. Mean winter temperature, mean summer temperature, vegetation cover, population abundance, proportion of winged individuals and female abdomen area were measured for each kissing bug population to construct a model. Lower genetic diversity was detected in populations at the edge of the distribution compared to those in the centre. However, genetic differentiation was not higher in the periphery. Genetic diversity was related to climatic and biological variables; there was a positive relationship with mean winter temperature and a negative association with mean summer temperature and body size. These results partially support the CPH and identify biotic (abdomen area) and abiotic (winter/summer temperatures) factors that would affect genetic diversity in this restricted-dispersal species of epidemiological relevance.

Wing dimorphism in semiaquatic bugs (Hemiptera, Heteroptera, Gerromorpha) as a tool for monitoring streams altered by oil palm plantation in the Amazon

Wing polymorphism is common in insects and is generally associated with environmental variation, thus, this characteristic can express different phenotypes under different environmental cues. Thereby, organisms with a greater dispersal capacity are more related to heterogeneous environments, while wingless organisms have a greater investment in reproduction even in habitats with suboptimal conditions. This study evaluated the efficacy of wing dimorphism in semiaquatic bugs as a tool to assess altered streams in oil palm plantations. We sampled 27 streams in the Eastern Amazon, classified in preserved areas and oil palm plantation areas. The total matrix of sites x species was broken down in two derived matrices, deconstructed in wingless and winged individuals. We evaluated the concordance between the derived matrices and the total matrix by Procrustes analysis. For each dataset, we used the t-test to evaluate the richness loss and model selection to assess the effect of environmental variables on species richness. There was a greater number of winged phenotype organisms in the preserved areas. Only the wingless matrix had a structure congruent with the overall community matrix. However, species loss of both wingless and winged individuals was observed in oil palm plantation areas. Wingless species richness was higher in areas with lower water temperature and a more closed canopy. On the other hand, winged species richness was higher at streams with lower temperature, pH, and depth. Also, our results emphasized the relationship between the expression of the winged phenotype and land use in polymorphic species. The greater abundance of winged individuals in preserved areas points to species such as Cylindrostethus palmaris and Brachymetra lata as potential targets for stream monitoring in the Amazon, as they are easily located and identified with no need for collection. These results suggest the wing polymorphism as a good strategy in environmental monitoring due to the reduction of time and financial costs required, also reducing the diversity loss that occurs in conventional biological collections. Additionally, they highlighted the trade-off between dispersal and reproduction in these areas, thus indicating that the wing polymorphic species life-history strategies can explain the environmental changes and contribute to the management of conservation policies for Amazonian aquatic ecosystems.

Emeryia, Xenometra, zoserka: it's a boy, again! The misleading morphology of Cardiocondyla male ants

Wingless “ergatoid” males of the ant genus Cardiocondyla have repeatedly been described as females of novel genera of workerless social parasites (Emeryia and Xenometra), which after recognition of their real nature were synonymized with Cardiocondyla. Examination of ants newly collected from Comoe National Park in Cote d’Ivoire, West Africa revealed that winged Cardiocondyla males have sparked a similar misidentification: the “winged female sexuals” of the supposed inquiline Cardiocondyla zoserka Bolton 1982, known only from the type material from Nigeria, are in fact the winged males of their presumed host, a species of the Cardiocondyla shuckardi group (sensu Seifert 2002). The types of C. zoserka are immediately recognizable by their strangely modified antennal funiculi with cup-shaped apical segments, which do not resemble any other known ant antenna. More than twenty winged individuals from two Cardiocondyla colonies from the flood plain of Comoe River exhibited the same strange modifications of their antennae and were otherwise also similar to the C. zoserka type specimens. However, these winged ants turned out to be winged males rather than winged female sexuals. The inspection of the holotype and one paratype of C. zoserka verified that they also were males: like the winged males from Comoe N.P., they have concealed male genitals and ocelli, which are considerably larger than those of the female sexuals of Cardiocondyla. All female sexuals and workers found in the colonies with the bizarre winged males from Comoe N.P. had antennae with a three-segmented club as is typical for this genus. Sequences of the mitochondrial cytochrome c oxidase subunits I (CO I) and II (CO II) of a winged male and two nestmate workers showed that they are close to C. venustula and C. shuckardi but differ from them in about 10% of the base pairs. Other samples of Cardiocondyla collected in Comoe N.P. belong to C. venustula and related species. Their males were always ergatoid or “intermorphic” (i.e., ergatoid with rudimentary wings), as previously found in other populations of C. venustula, and never winged with modified antennae.

Morphological Variation Tracks Environmental Gradients in an Agricultural Pest, Phaulacridium vittatum (Orthoptera: Acrididae).

Invertebrate pests often show high morphological variation and wide environmental tolerances. Knowledge of how phenotypic variation is associated with environmental heterogeneity can elucidate the processes underpinning these patterns. Here we examine morphological variation and relative abundance along environmental gradients in a widespread agricultural pest, native to Australia, the wingless grasshopper Phaulacridium vittatum (Sjöstedt). We test for correlations between body size, wing presence, and stripe polymorphism with environmental variables. Using multiple regression and mixed-effects modeling, body size and stripe polymorphism were positively associated with solar radiation, and wing presence was positively associated with foliage projective cover (FPC). There were no associations between body size or morphological traits with relative abundance. However, relative abundance was positively associated with latitude, soil moisture, and wind speed, but was negatively associated with FPC. Therefore, sites with low relative abundance and high forest cover were more likely to contain winged individuals. Overall, our results suggest that environmental and climatic conditions strongly influence the relative abundance and the distribution of morphotypes in P. vittatum, which is likely to affect dispersal and fitness in different landscapes. This knowledge is useful for informing how environmental change might influence the future spread and impact of this agricultural pest.

Comparative thermoregulation between different species of dung beetles (Coleoptera: Geotrupinae)

Insects can use thermoregulation to keep their body temperatures within a certain range in response to thermal stress situations. The mechanisms to regulate internal temperature depend on whether species are endothermic or ectothermic species, i.e., if the heat source is internal and/or external. In this study, the thermal stress response due to excess heat was examined in individuals belonging to different species of the Geotrupinae subfamily by using a standardized protocol based on infrared thermography. All the measured heat stress variables allow discrimination among the considered species to a greater or lesser extent. The body heating rate in the heat stress range, the critical thermal maximum and the stress start temperature were the most important variables in discriminating between apterous and winged individuals (R2 = 52.5%, 51.1% and 50.0%, respectively). Examining the degree of association between the physiological similarity of individuals and some species traits suggest that flying capability and daily activity are related with different thermal responses. Based on the obtained results, the Geotrupinae subfamily can be divided into three ecophysiological groups: good, medium and non-thermoregulators. Within these groups, apterism appears mainly in those species with the ability to actively decrease their body temperature. Our results indicate that this ability may be partially due to the management of water loss related with evaporative cooling.

Багаторічна динаміка щільності стану розвитку міжвидових популяцій злакових попелиць (Homoptera, Aphididae) упродовж вегетації пшениці озимої в умовах Лісостепу України

Багаторічна динаміка щільності стану розвитку міжвидових популяцій злакових попелиць (Homoptera, Aphididae) упродовж вегетації пшениці озимої в умовах Лісостепу України

Wing morphology is linked to stable isotope composition of nitrogen and carbon in ground beetles (Coleoptera: Carabidae)

As movement is expensive in terms of energy required, mobile animals might have to utilize more energy rich resources than less mobile animals. As mobile animals are possibly more effective foragers we hypothesize a positive correlation between mobility and trophic niche width. We address this link using information on the trophic level of 35 winged, wingless and wing dimorphic species of ground beetles studied on 18 lake islands and at two mainland sites in northern Poland. Trophic analyses using stable isotope values (δ15 N, δ13C) revealed that winged individuals of wing dimorphic species are characterized by broader isotopic niches than wingless individuals. Macropterous species are characterized by depleted δ13C values, which can be interpreted in terms of lipid-rich prey selection. Wing dimorphic species are characterized by higher trophic levels, as inferred from δ15 N values, than winged species. Numbers of islands colonized by particular species were not correlated with δ15 N values, δ13C values or isotopic niche width. Our results point to a relationship between diet and wing morphology in ground beetles.

昆虫翅型分化的表型可塑性机制

PDF HTML阅读 XML下载 导出引用 引用提醒 昆虫翅型分化的表型可塑性机制 DOI: 10.5846/stxb201310302610 作者: 作者单位: 中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院森林生态环境与保护研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(31370654) Mechanisms of phenotypic plasticity for wing morph differentiation in insects Author: Affiliation: Key Laboratory of Forest Protection,State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Protection,State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Protection,State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Protection,State Forestry Administration,Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:翅多型现象在昆虫中广泛存在,是昆虫在飞行扩散和繁殖能力之间权衡的一种策略,对种群的环境适应性进化具有重要的意义。目前在植食性昆虫中研究较多,有关寄生蜂的翅型分化鲜见报道。综述了昆虫翅型分化的表型可塑性机制。遗传因素和环境因素均对昆虫翅的发育产生影响,基因型对翅型的决定具有显著作用,外界环境条件,包括温度、光周期、食物质量、自身密度、外源激素等因素对昆虫翅的发育也产生重要的调节作用,从而产生翅的非遗传多型性现象。此外,天敌的寄生或捕食作用可能会诱导某些昆虫的翅型产生隔代表型变化。对昆虫产生翅多型现象的生态学意义及其在生物进化过程中的作用进行了讨论,并探讨了寄生性昆虫翅型分化机制在生物防治上的可能应用途径。功能基因组学和表观遗传学的进一步发展可望为彻底揭示昆虫翅型分化机制提供新的机遇和技术手段。 Abstract:Phenotypic plasticity is a phenomenon in which the same genotype produces entirely different phenotypes in response to changes in the environment, and grants an organism the ability to adapt to environmental variations. Wing polymorphism is commonly observed in insects, including Homoptera, Hemiptera, Coleoptera, Hymenoptera, Orthoptera, Diptera, Lepidoptera, Isoptera, Psocoptera, and Dermaptera, as a strategy to tolerate trade-offs between flight capability and fecundity. As a result, it may confer an important adaptive value to the evolution of populations because these winged individuals can migrate long distances and find suitable habitats for development and reproduction of their offspring more easily. At the present time, there is limited knowledge of the mechanisms of wing polymorphism in varying populations. Both genes and the environment are usually considered to affect the developmental outcomes of insect wing morphs. It is easy to understand the contributions of genes to morphology as a consequence of the research of evolution and developmental biology. However, very little is known about the influential mechanism of environmental factors on the development of phenotypes. In fact, it is not yet clear that how the evolutionary shifts of character variation is realized between environmental and genetic control. So far, studies on wing polymorphism are mostly reported on phytophagous insects, very few are known in parasitoids, natural enemies of insect pests. Here we summarized the mechanisms of phenotypic plasticity for wing morph differentiation in insects. Both genetic and environmental factors can act on the wing development of insects. The genotypes have significant effects on the determination of insect wing morphs. External environmental conditions such as temperature, photoperiod, food quality, population density, exogenous hormones, etc., also play important roles in regulating the insect wing development, which produce wing polyphenism. In addition, the parasitism or predation of natural enemies may induce alternative variations across transgenerational wing morphs in some insects. The ecological significance of insect wing polymorphism and its functions during their evolutionary process are discussed. Polyphenism is one of the main reasons why insects have become so successful on the earth, and grants them the capability to effectively utilize the same genome in order to best adapt to predictable changes in the environment, such as degradation of survival conditions after overcrowding, by developing into different phenotypes. Wing polyphenism in insects is a clear example of adaptive phenotypic plasticity, which provides a very good model to study alternative phenotypes from both genetic and environmental perspectives. This may also be advantageous to evaluate how environmental and genetic factors jointly control the same developmental events. Further study recommendations were also discussed in this review, as well as the potential utilization of wing morph differentiation mechanisms of parasitic wasps in biological control, e.g., through artificially culturing the winged individuals of parasitoids for field release to improve the dispersal ability of natural enemies. Some critical aspects still need to be investigated further on the mechanisms of phenotypic plasticity for wing morph differentiation in insects. Further development in functional genomics and epigenetics may provide novel opportunities and technological support for revealing the mechanisms of polyphenism in insects completely. 参考文献 相似文献 引证文献

Endemic aphidsAphis carveraesp. nov. andCasimira canberrae(Eastop, 1961) onEpilobium(Onagraceae) threatened by introducedAphis oenotherae Oestlund, 1887 (Hemiptera: Aphididae: Aphidinae)

We describe the wingless viviparae and sexual forms of Aphis carverae sp. nov., a new endemic species of Aphis Linnaeus, 1758 from Australia. The species is holocyclic and monoecious on Epilobium (Onagraceae). No winged individuals have been found. Casimira canberrae (Eastop, 1961) is another endemic aphidine species from Epilobium. We describe the winged viviparous and wingless sexual female morphs of this aphid, which is also shown to be holocyclic and monoecious. Native aphids feeding on Onagraceae in Australia are under serious competitive threat from the recently introduced Aphis oenotherae Oestlund, 1887.

Alate production in an aphid in relation to ant tending and alarm pheromone

1. Winged dispersal is vital for aphids as predation pressure and host plant conditions fluctuate.2. Ant‐tended aphids also need to disperse, but this may represent a cost for the ants, resulting in an evolutionary conflict of interest over aphid dispersal.3. The combined effects of aphid alarm pheromone, indicating predation risk, and ant attendance on the production of winged aphids were examined in an experiment with Aphis fabae (Homoptera: Aphididae) (Scopoli 1763) aphids and Lasius niger (Formicidae: Formicinae) (Linné, 1758) ants.4. This study is the first to investigate the joint effects of alarm pheromone and ant attendance, and also the first to detect an influence of alarm pheromone on the production of winged morphs in A. fabae.5. After a period of 2 weeks, it was found that aphid colonies exposed to intermittent doses of alarm pheromone produced more winged individuals, whereas ant tending had the opposite effect. The effects were additive on a log scale, and ant attendance had a greater proportional influence than exposure to alarm pheromone. A tentative conclusion is that ants have gained the upper hand in an evolutionary conflict about aphid dispersal.

Functional Role of Dragonfly Legs before and after Wing Formation: Rearrangement of Coordinatory Relationships

We report here our studies of the characteristics of the structural-functional organization of the leg apparatus of the dragonfly Aeshna grandis, in larvae of the final instar, whose legs have a locomotor function, and in adult winged individuals (imagoes), whose legs have lost their locomotor function and are used mainly as traps to catch prey in the air. Neither the shape nor the proportions of individual leg segments in imagoes were significantly different from those in larvae, and all changes in the functional role of the legs in imagoes occur as a result of changes in the mechanisms controlling the functioning of the leg muscles and the corresponding rearrangements in coordinatory relationships. These rearrangements, as evidenced by the data reported here, affect the mechanisms generating motor commands, the appearance of a tight correlation in the operation of the wing muscles and the leg apparatus, and various others. These mechanisms are discussed.

Mechanisms of species‐sorting: effect of habitat occupancy on aphids' host plant selection

Interspecific interactions such as competition are important factors affecting insect herbivore fitness. Host choice in herbivorous insects including aphids has largely been studied with respect to host plant condition, while the role of competition is also very important. Tansy (Tanacetum vulgare L.) hosts three specialised aphids, Macrosiphoniella tanacetaria (Kaltenbach), Metopeurum fuscoviride Stroyan and Uroleucon tanaceti (L.) (Hemiptera: Aphididae). In this study, a set of greenhouse and field experiments were carried out to investigate whether aphid host plant choice was affected by the presence of the other aphid species. When winged individuals were given the choice between unoccupied plants and plants occupied by the same or another aphid species, choices generally reflected the outcome of competitive interactions among aphids. Colonisation of plants by winged individuals was influenced not only by the presence of other aphids on the host plant but also by previous infestation. The host choice of winged individuals basically reflected competitive hierarchies, i.e. aphids in most cases selected plants where future competition was less likely. By contrast, unwinged aphids did not show any host plant preference. For M. tanacetaria previously infested plants promoted the production of winged offspring. Our results show that competitive interactions could affect host selection behaviour by aphids. In a metacommunity context, such preferences in colonising different habitats leads to species‐sorting through habitat heterogeneity.

Multiple Cues for Winged Morph Production in an Aphid Metacommunity

Environmental factors can lead individuals down different developmental pathways giving rise to distinct phenotypes (phenotypic plasticity). The production of winged or unwinged morphs in aphids is an example of two alternative developmental pathways. Dispersal is paramount in aphids that often have a metapopulation structure, where local subpopulations frequently go extinct, such as the specialized aphids on tansy (Tanacetum vulgare). We conducted various experiments to further understand the cues involved in the production of winged dispersal morphs by the two dominant species of the tansy aphid metacommunity, Metopeurum fuscoviride and Macrosiphoniella tanacetaria. We found that the ant-tended M. fuscoviride produced winged individuals predominantly at the beginning of the season while the untended M. tanacetaria produced winged individuals throughout the season. Winged mothers of both species produced winged offspring, although in both species winged offspring were mainly produced by unwinged females. Crowding and the presence of predators, effects already known to influence wing production in other aphid species, increased the percentage of winged offspring in M. tanacetaria, but not in M. fuscoviride. We find there are also other factors (i.e. temporal effects) inducing the production of winged offspring for natural aphid populations. Our results show that the responses of each aphid species are due to multiple wing induction cues.