Functional Responses of Feral and Colonized Strains of Neoseiulus Idaeus Denmark & Muma Feeding on the Cassava Green mite Mononychellus Tanajoa (Bondar) (Acari: Phytoseiidae, Tetranychidae)

Abstract

The effect of long term laboratory breeding on the functional response of the Neotropical predatory mite Neoschulus idaeus Denmark and Muma (Acari: Phytoseiidae) was studied under laboratory conditions. Cassava green mites Mononychellus tanajoa (Bondar) (CGM) eggs are used as prey at densities of 1,3,5,10,20,30,40,50 and 60, foraging in a 3.14cm² leaf disc of "Odongbo", a local CGM-susceptible cassava variety. All functional responses observed were of the Holling type II curve with plateaux determined by predator's strain and desity. Mean highest number of 16,5 CGM eggs/5hrs consumed by feral N. idaeus was significantly different from the 14.7 CGM eggs/5hrs by colonized N. idaeus for females foraging singly (P<0.05). Mutual interference among predators in the same arena was significantly greater (P<0.05) for the feral strain and increased at higher predator density. The quest constant, search rate and killing power of the feral strain was superior to those colonized strain. There was significant negative correlation between predator's search rate and prey density in all treatments. Laboratory selection of individuals with low predatory attributes and therefore inferior biological control agents when given CGM prey is suggested.