Rearing and development of Oligota pygmaea and Parastethorus histrio (Coleoptera: Staphylinidae, Coccinellidae) feeding on Oligonychus yothersi (Acari: Tetranychidae) and survival on non-mite foods under laboratory conditions

Oligota pygmaea and Parastethorus histrio are predators of Oligonychus yothersi, the most detrimental foliar pest of the avocado in Chile. Their incorporation and conservation as biological control agents in Integrated Pest Management programmes requires the development of rearing methods and life cycle studies. This paper studied the effects of different materials (gypsum plaster impressed with an array of shallow holes, wooden boxes imbedded in a gypsum block and corrugated cardboard placed on a smooth gypsum plaster base) on the survival, development and longevity of pupae and adults of O. pygmaea and P. histrio preying on O. yothersi. Oligota pygmaea pupae registered over 93% of survival on honeycombed gypsum plaster, this being a useful material to rear and maintain both predators. The egg-to-adult period was 24.38 ± 0.98 days for O. pygmaea and 19.64 ± 1.07 days for P. histrio, whereas the longevity of O. pygmaea adults was 134.03 ± 4.66 days and 120.47 ± 4.46 days for P. histrio. In addition, the study evaluated the survival time of both predators feeding on whitefly Aleurothrixus floccosus (Aleyrodidae) colonies, walnut aphid Chromaphis juglandicola (Aphididae) honeydew, honey and water. When fed with whitefly colonies the O. pygmaea females survived 31.2 ± 4.91 days and P. histrio survived 21.67 ± 2.69 days, indicating that, at moments of tetranychid scarcity, both predators exploit other food resources to survive.