predation consequence of continuous breeding vs starting a new colony of a polyphagous insect predator

The predation rates of a recently collected population of the mirid Macrolophus pygmaeus versus one continuously bred in the laboratory, reared under the same conditions for three generations, were compared in 24-h choice experiments using first to fourth instar nymphs of the aphid Myzus persicae on aubergine and sweet pepper. On aubergine, the mean wet weights for first, second, third and fourth instar nymphs of M. persicae were 46%, 36%, 8% and 14% greater, respectively, compared with aphids on pepper. Adult females from a recently collected field population of M. pygmaeus (MpK) consumed more second and third instars compared with first and fourth instars on aubergine and pepper (79% and 88% of biomass consumed, respectively). M. pygmaeus females (MpV) from a population maintained in the laboratory for more than 15 years consumed more first and second instar nymphs on aubergine. On pepper, consumption by MpV females was relatively constant between instars and unlike other combinations, where third instars contributed the greatest amount of biomass consumed (43–60%), fourth instars contributed the most biomass consumed (51%). The total aphid biomass consumed by the MpK population was twofold greater on pepper and 4.7-fold greater on aubergine when compared with the MpV population. The MpK population consumed more aphid biomass on aubergine compared with pepper while the reverse was the case for the MpV population. Such intraspecific differences may have a significant influence on their efficacy as predators in biological control systems.