Comparative Behavioural Studies of Larval and Adult Stages of the Phytoseiids (Acari: Mesostigmata) Typhlodromus Athiasae and Neoseiulus Californicus

Abstract

We compared the behaviours of the indigenous Typhlodromus athiasae Porath and Swirski and the exotic Neoseiulus californicus (McGregor) (= Amblyseius chilenensis Dosse) relative to their persistence in apple orchards in Israel. We studied (1) larval feeding, walking, intraspecific interactions (cannibalism, touch-avoidance responses and/or touching with palps and tarsi) and tendency to aggregate (when resting), (2) predation and cannibalism on phytoseiid eggs by young females and (3) the effects of starvation for 10 days on young females relative to ambulation speed, longevity, fecundity, progeny survival and sex ratio. Larvae of T. athiasae were almost inert, did not feed and hardly walked or interacted whereas larvae of N. californicus fed, walked and interacted, mainly by touching with palps and tarsi. No cannibalism in the larval stage was observed for either species. The presence of prey increased the larval walking and intraspecific interactions of N. californicus but not of T. athiasae. Egg predation by adult females of both species was substantially higher than cannibalism, implying that both are capable of distinguishing their eggs from those of other species. Soaking eggs for 30 min in deionized water increased cannibalism in both species. During the 10 days of starvation, the ambulation speed of adult female N. californicus ranged from 1.8 to 10.1 times that of T. athiasae. The 50% lethal time value (LT50) of T. athiasae (6.0 days) was significantly lower than that of N. californicus (10.4 days). None of the starved T. athiasae recuperated following the reintroduction of prey, whereas 75% of N. californicus did and oviposited after 2 days. These traits should enable N. californicus to persist when prey is scarce; however the selective predation of N. californicus eggs by T. athiasae could prevent establishment of N. californicus. The degree of specialization of these two predators is discussed.