Abstract
Although there are few studies of the sexual life of coccinellids these phenomena have attracted the interest of isolated groups of coccinellidologists. Probably the most important finding is that at least some coccinellid species (Adalia bipunctata and Harmonia axyridis) do not mate at random with the females prefering certain males. This phenomenon was first observed in Adalia bipunctata by Lusis and then studied in detail by Majerus, O'Donald, de Jong and others. In Japan, Harmonia axyridis was similarly studied by Osawa and Ueno. While the former author found that in this species (as in A. bipunctata) the colour of the elytra is most important in mate choice by females, the latter stresses that size and activity are important. Sperm competition is another interesting phenomenon, most often the sperm of the last male fertilizes the eggs (Ueno, Katakura). Obata and Hidaka have contributed in an important way to elucidating the function of the spermatophore in mating. The studies by Hodek and Ceryngier recorded the maturation and regression of testicular follicles and the relation of mating activity to diapause in four coccinellid species. In contrast to females, where induction of diapause prevents maturation of ovaries, in diapausing males the tissue of testicular follicles remains active until the temperatures decrease in late autumn. Dissection of spermathecae revealed principal difference in autumn mating activity between Coccinella septempunctata, in which 40-60% of the beetles mated before hibernation and Ceratomegilla (syn. Semiadalia) undecimnotata, which does not mate in autumn.
Highlights
The studies on coccinellids have naturally concentrated on their relation to prey: prey specificity, quantitative aspects, prey foraging behaviour and impact
The very limited range of coccinellid species studied so far needs to be widened before general predictions about evolutionary trends in mating behaviour can be made
By means of selection experiments the authors demonstrated that the preferential mating has a large genetic basis (Majerus et al, 1982 a): the incidence of females mating with melanic males increased to 57% in the 4th genera tion (Table 3)
Summary
The studies on coccinellids have naturally concentrated on their relation to prey: prey specificity, quantitative aspects, prey foraging behaviour and impact. The development of gonads and mating have always been much less studied, they have some practical relevance, when coccinellids are reared as predators to be used in biological control. The little interest in the sexual activity of ladybirds, shown by a limited number of authors quoted here, inspired us to write this review. While the review does not attempt to be exhaustive, the aim of authors has been to stimulate fur ther research in this field, or at least provide information. The very limited range of coccinellid species studied so far needs to be widened before general predictions about evolutionary trends in mating behaviour can be made
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