RESPONSES OF AMBLYSEIUS-OVALIS (EVANS) (ACARINA, PHYTOSEIIDAE) TO NATURAL FOOD RESOURCES AND 2 ARTIFICIAL DIETS

Six phytophagous mites, maize pollen, and two artificial diets were fe d to Amblyseius ovalis to evaluate their food suitability for the pred ator. The parafilm diet-chip of Hager and Tassan was adopted for artif icial diet studies. The floating leaf method was the best among all te sted methods, producing high survival, developmental, and reproductive rates of the predator. Offspring of A. ovalis feeding on artificial d iets did not complete their life cycles. A. ovalis feeding on E. orien talis, O. mangiferus, ad O. taiwanicus developed into adult form faste r than those feeding on other food resources. Predators feeding on the natural food, except those feeding on T. kanzawai, had much higher im matural survival rates, lower escape rates, and shorter developmental durations than those feeding on the artificial diets. All A. ovalis la id an average of two eggs per female per day after 2 days of preovipos ition, except for those feeding on T. kanzawai which produced none. A. ovalis feeding on artificial diets showed a shorter oviposition perio d, lower daily and total reproductive rates, and shorter longevity. Th e complicated webbing life type of T. kanzawai inhibited the activitie s of A. ovalis, indicating that the predators may require nutrients ot her than T. kanzawai eggs to molt into adults and to reproduce. The fu nctions varying the phytoseiid-tetranychid relationship during the pre dator's approach to the microhabitat of the prey were postulated from the predator's structures and the prey's life type. Most predator eggs were laid by 2-18 day-old females feeding on natural food resources. A. ovalis retained its high activity on the low webbing habitats of O. mangiferus and E orientalis, and on maize pollen. The intrinsic rate of increase, mean generation time, and net reproductive rate of A. ova lis on each of nine tested food resources were evaluated from its life tables. The predator showed the highest intrinsic rates of increase w hen feeding on the prey of E orientalis, O. mangiferus, and on maize p ollen, and the lowest rates when feeding on the artificial diet even w hen the immatures had fed on the O. mangiferus and maize pollen. Conse quently, the optimal food resources for A. ovalis appear to be O. mang iferus or O. orientalis with supplements of maize pollen. When fed on these food resources, the predators demonstrated the highest rates of survival, longevity, fecundity, and intrinsic increase.