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Abstract

Laboratory studies were carried out to assess the effects of feeding on different prey species either individually or in a sequential combination, on the development, survival and reproduction of Nephaspis bicolor Gordon (Coleoptera: Coccinellidae). Three species of Aleyrodidae were used as prey, two from the subfamily Aleurodicinae (Aleurodicus cocois Curtis and Aleurodicus pulvinatus Maskell on coconut and seagrape, respectively), and one from the subfamily Aleyrodinae (Aleurothrixus floccosus Maskell on guava). Based on development rate and the size of adults, A. floccosus was the most suitable prey for larvae. Prey species affected lifetime fecundity with beetles ovipositing significantly more eggs when fed A. floccosus. Rearing N. bicolor on A. floccosus and A. cocois produced the fittest adults in terms of population growth statistics. Prey substitution in larval stages did not affect survival or the duration of development. However, switching newly-emerged adults to a prey different from that fed on as larvae resulted in an increased preoviposition periods. Based on these data, it is concluded that the N. bicolor is adapted to utilize prey from both whitefly subfamilies and can readily switch between prey types in accordance with changes in their availability. Thus, any biological control programme that plans to introduce the coccinellid as a predator of Aleyrodidae needs to take this into consideration in the risk analysis / decision-making process.

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