Exploring and exploiting natural variation in the wings of a predatory ladybird beetle for biological control
2013
Lommen, S.T.E.
The central theme of this PhD thesis is natural variation in the wing length of the predatory two-spot ladybird beetle, Adalia bipunctata. ‘Wingless’ individuals of this species occur occasionally. They possess truncated wing covers and flight wings and cannot fly, but the extent of the reduction is highly variable between individuals. At one hand, I take a multidisciplinary experimental approach to study the causes and consequences of this variation in an evolutionary context. Genetic and developmental studies show that it is regulated by several polymorphic genes, and results from gene-environment interactions affecting the growth of the larval wing discs. Studies on life-history traits and mating behaviour provide no evidence that winglessness is an adaptive trait in this ladybird. However, they reveal a function of the wing covers in survival and mating behaviour. On the other hand, I examine the use of wingless ladybirds in the biological control of aphids, since winged ladybirds are not effective when flying away soon after release. I show that wingless morphs have the potential to improve biocontrol efficacy. I then suggest that mass-rearing of this less fit morph could be improve by manipulation of the wing length. Altogether, this thesis interlinks the fields of fundamental (evolutionary) biology and applied biological control.
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