Daily consumption and predation rate of different Stethorus punctillum instars feeding on Tetranychus urticae

Abstract

Laboratory experiments were conducted to evaluate the prey stage preference and the daily consumption of each stage of the coccinellid predator Stethorus punctillum Weise (Coleoptera: Coccinellidae) feeding on the two-spotted spider mite Tetranychus urticae (Koch) (Acari: Tetranychidae). Groups of different life stages of the prey were offered (eggs, larvae, nymphs and adults). The prey preference varied with the stage of S. punctillum. First larval instars had no significant preference among the T. urticae stages offered. Second larval instars consumed significantly more spider mite larvae in comparison with nymphs. In contrast, third larval instars indicated a strong preference for mite eggs. Significantly fewer T. urticae larvae were consumed by the fourth larval instars of S. punctillum, in comparison with the three other mite stages. Finally, adult predators consumed significantly more mite eggs than the other stages offered. This preferential trend was similar for all adults tested, whether during the pre-oviposition or the oviposition period.