Comparative behavioural studies of larval and adult stages of the phytoseiids (Acari : Mesostigmata) Typhlodromus athiasae and Neoseiulus californicus

We compared the behaviours of the indigenous Typhlodromus athiasae Porath a nd Swirski and the exotic Neoseiulus californicus (McGregor) (= Amblyseius chilenensis Dosse) relative to their persistence in apple orchards in Israe l. We studied (1) larval feeding, walking, intraspecific interactions (cann ibalism, touch-avoidance responses and/or touching with palps and tarsi) an d tendency to aggregate (when resting), (2) predation and cannibalism on ph ytoseiid eggs by young females and (3) the effects of starvation for 10 day s on young females relative to ambulation speed, longevity, fecundity, prog eny survival and sex ratio. Larvae of T. athiasae were almost inert, did no t feed and hardly walked or interacted whereas larvae of N. californicus fe d, walked and interacted, mainly by touching with palps and tarsi. No canni balism in the larval stage was observed for either species. The presence of prey increased the larval walking and intraspecific interactions of N. cal ifornicus but not of T. athiasae. Egg predation by adult females of both sp ecies was substantially higher than cannibalism, implying that both are cap able of distinguishing their eggs from those of other species. Soaking eggs for 30 min in deionized water increased cannibalism in both species. Durin g the 10 days of starvation, the ambulation speed of adult female N. califo rnicus ranged from 1.8 to 10.1 times that of T. athiasae. The 50% lethal ti me 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 recuperate d 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. californ icus eggs by T. athiasae could prevent establishment of N. californicus. Th e degree of specialization of these two predators is discussed.