Tetranychus urticae density on variety of plant leaves influencing predatory mite Euseius scutalis functional response

Abstract

The functional response of adult females of the predatory mite Euseius scutalis (Athias-Henriot) was assessed at different prey densities of immature Tetranychus urticae Koch and variable plant texture using six plants (Cucumis sativus, Phaseolus vulgaris, Capsicum annuum, Vitis vinifera, Ficus carica and Cucumis melo). The present results demonstrated that the change in predation rate of E. scutalis is caused by the structural and morphological characteristics of the leaf and prey density. The handling time per prey item (Th) of the functional response for the E. scutalis changed with plant leaf type and numerical density of the prey. The shortest handling time was on P. vulgaris, while the highest handling time was on C. melo. It was evident that the searching efficiency (a') was highest on C. annuum, while lowest on C. melo. On P. vulgaris and C. melo there was significant difference in the mean number of prey killed at the different prey densities. Curves of functional response matched those of the type II response model, implying inverse density-dependence in addition to a positive quadratic coefficient. These findings highlight the significance of host plant traits and prey density on E. scutalis performance and in optimizing natural enemy usage in biological pest management.