Host plant effects on the functional response ofNeoseiulus cucumeristo onion thrips larvae

Abstract

Abstract: The performance of herbivores, natural enemies and their interactions may be affected directly or indirectly by host plant traits, e.g. the physical plant characteristics may influence the search pattern and the functional response of predators. We studied the functional response of adult females of the predatory miteNeoseiulus cucumeristo first instar larvae ofThrips tabacion three host plants (sweet pepper, eggplant and cucumber). The 24‐h leaf disc experiments conducted at 25 ± 1°C, 60 ± 10% relative humidity and 16 : 8 h (light : dark) showed thatN. cucumerisexhibited a type II functional response on all host plants. The following search rates and handling times were estimated from fitting the data to the disc equation 0.043/h and 1.798 h (cucumber); 0.048/h and 1.030 h (sweet pepper) and 0.0441/h and 2.294 h (eggplant) giving an estimated maximum predation of 13.35, 23.31 and 10.46 larvae per day respectively. The data from sweet pepper could also be described by the random predator equation (a′: 0.051/h;Th: 0.472 h). The host plant species interacted significantly with prey density on the functional response ofN. cucumeriswith the relative differences in the number of thrips eaten on each host plant increasing with density. It is suggested that it is mainly the difference in trichome density between the three host plants that is responsible for the observed differences in the functional response ofN. cucumeris. These results emphasize the importance of the host plant characteristics on the performance of natural enemies and for optimizing their use in biological control of pests.