Influence of predator density, diet and living substrate on developmental fitness of Orius laevigatus

Abstract

Mass rearing of Orius laevigatus on non-insect foods could substantially increase the cost-effectiveness of the production of this biological control agent which is largely based on the use of expensive eggs of the Mediterranean flour moth Ephestia kuehniella. In this study, the effect of substrate quality and predator density on nymphal development of O. laevigatus fed on E. kuehniella eggs, honeybee pollen or an egg yolk based artificial diet was assessed using several types of substrates as shelter materials in the rearing containers (wax paper, bean pod or no extra substrate). In general, E. kuehniella eggs proved to be a nutritionally superior food compared to pollen and artificial diet. Pollen supported nymphal development of O. laevigatus better than the artificial diet. Overall, increasing nymphal density resulted in higher mortality, which may be due in part to cannibalism. The addition of a bean pod compensated for the nutritionally suboptimal artificial, but had a negative effect when O. laevigatus was fed on pollen. The non-insect foods tested could not adequately replace lepidopteran eggs as a food source for O. laevigatus but they may be useful as an alternative food or in a part of the rearing process.