Time Allocation of Activities of Two Heteropteran Predators on the Leaves of Three Tomato Cultivars with Variable Glandular Trichome Density

Abstract

Abstract Plant glandular trichomes can confer protection from herbivores, but may also affect natural enemies. We studied time allocation of activities (inactive, moving, probing, feeding, and grooming) of nymphs of the predatory bugs Macrolophus pygmaeus and Orius niger on the upper surface of tomato leaflets from the cultivars Dombito, Elxis, and H30. In H30, which had the highest density of type VI glandular trichomes on the upper surface, both insects spent more time in grooming their tarsi and rostrum than the other two cultivars. In Dombito and Elxis, which have trichome densities that didn’t differ much, no significant differences were observed in time allocation of activities for both insects. When averaged across cultivars, younger instars of M. pygmaeus spent less time on probing and more time on grooming, whereas for O. niger, the nymphs of first stage spent more time on grooming and less on movement than the nymphs of older stages. Between species, O. niger first instars groomed more and walke...