Prey kills predator: Counter-attack success of a spider mite against its specific phytoseiid predator

Abstract

Success of counter-attack by the spider mite,Schizotetranychus celarius (Banks), against its specific phytoseiid predator,Typhlodromus bambusae Ehara, was examined under experimental conditions. The success of counter-attack by prey females (“mothers”) against a predaceous larva depended upon the former's density per nest. About 30% of the predaceous larvae were killed when they intruded into a nest containing eight females and their offspring. On the other hand, the prey males (“fathers”) effectively killed the predators, i.e. one male in the nest killed ca. 40% of the predators while two or three males destroyed up to 80%. The presence of prey parents in a nest considerably enhanced the success of the counter-attack. One male and two young females could kill 70% of the predator's larvae, while two males and two females killed 90% of such larvae. This suggests a kind of cooperative brood defence amongstS. celarius parents. Although more robust, protonymphs of the predator also suffered damage by the prey's counter-attack. However, prey male and female could not destroy the predator's eggs and adult females, whilst the latter often killed spider mite adults. From these as well as previous experiments, it is concluded thatS. celarius has evolved some kind of biparental care for its offspring. It is further proposed that the predator—prey interactions observed in this study provide a unique contribution towards understanding “predator—prey coevolution”.