In this review article the available information on the wing dimorphism/polymorphism occurring at non-phytophagous Heteroptera is reviewed from a functional viewpoint. This meant practically the information about the wing dimorphism/polymorphism of the superfamily Gerroidea, as hardly anything has been published on this theme of other non-phytophagous Heteroptera. Seasonal and concurrent wing dimorphism/polymorphism are treated and discussed separately. Heritability and phenotypical plasticity of the wing form, and the effects of different modifying environmental factors are briefly reviewed and discussed. The superior reproductive ability of the non-macropterous form is well documented at female gerroid bugs; there are less available data on the males. The seasonal wing polymorphism directed by photoperiod and affected by temperature is usually well adapted to the current environmental conditions. The effects of the population density and that of the food quantity and quality on wing form of the gerroid bugs have not been well understood yet; and it is arguable, whether the macropterous/non macropterous ratio of the natural gerroid populations corresponds to the temporal stability of their actual habitats in an adaptive way. Wing dimorphism/polymorphism has to be evaluated within the wider concept of dispersal polymorphism, which includes other related phenomena like wing muscle polymorphism and behavioural differences.

This is the second part of the article where the available information from the published literature on the wing dimorphism/polymorphism occurring among true bugs (Heteroptera) is reviewed from a functional viewpoint. This paper covers the case studies on phytophagous species and draws some general conclusions. Wing dimorphism/polymorphism has been studied in detail at the red firebug: Pyrrhocoris apterus (Linnaeus, 1758), at some blissid species - mainly at the Oriental chinch bug: Cavelerius saccharivorus (Okajima,1922) - at some lygaeid species and at the red-shouldered soapberry bug Jadera haematoloma (Herrich-Schäffer, 1847) (Rhopalidae). In general, the macropterous form has a delayed sexual maturation, which further enhances its dispersal ability but represents an obvious reproductive disadvantage. In most known cases of the hemipteran wing dimorphism/polymorphism the wing form is affected by environmental factors (polyphenism), but examples of genetically determined wing dimorphism also have been documented among Lygaeinae. Seasonal wing dimorphism/polymorphism is very common among the well-studied northern temperate species. Wing dimorphic/polymorphic phytophagous “outbreak” species (Blissidae, Leptoterna dolobrata) react with mass production of the otherwise rare macropters to high population density and altered food quality. An underlying wing muscle dimorphism/polymorphism frequently co-exists with the externally visible wing dimorphism/polymorphism. Known cases of full or partial de-alation are also mentioned and briefly discussed.

In this article the available information on the effects of host plant’s nitrogen fertilisation on the preference/performance of the sap-sucking insects (Hemiptera) and on host plants tolerance is reviewed. There is a very strong general tendency that nitrogen fertilisation increases the preference/performance of the sap sucking insects. Important exceptions are known, when the excessive nitrogen fertilisation decreases the preference/performance of the hemipteran herbivores. Host plant tolerance usually improves with nitrogen fertilisation: exceptions are known when the herbivore is very efficient in exploiting the host plants nitrogen content. Relationship is affected by the host plants and herbivore’s genotype and by the type and the mode of application of the fertiliser. Direct underlining causes are complex and still not entirely known. Nitrogen fertilisation can affect the herbivore through changing the concentrations and ratios of the available nutrients in the plants and/or changing the concentrations of the host plant’s defensive chemicals.

In this review article the invasive potential of wing dimorphic and polymorphic insects is discussed by presenting two case studies and overviewing the general knowledge of the dispersal abilities of these insects. Flying morphs of the wing dimorphic rice planthoppers Nilaparvata lugens and Sogatella furcifera continuously re-invade the rice fields in Japan and Northern China, where subsequent generations of dimorphic populations build up, causing several economic damages. The rapid range expansion of the wing dimorphic bush cricket Metrioptera roeselii in Central and Northern Europe in the 2000s was documented and extensively studied. These case studies are analysed, and the general relation of wing dimorphism and polymorphism and invasive potential is briefly discussed using the extensive knowledge on the wing dimorphism and polymorphism present in different insect orders.

The aggregation behaviour and the senescence inducing effect on its host plants (Glyceria spp.) of the European chinch bug (Ischnodemus sabuleti) is documented in several Hungarian high- density populations. The hypothesis of intraspecific facilitation through host plant quality improvement is formulated and discussed in detail. We suggest that drought stressed host plants improve the performance of I. sabuleti and facilitate the local population outbreaks. We suggest that the optimal host plant drought stress level is higher for senescence feeding herbivores than for the flush feeding herbivores.