Food preference and some biological aspects of the predator Stethorus gilvifrons (Muls) (Coccinellidae: Coleoptera) on deferent stages of Tetranychus urticae Knock- on cotton


A laboratory experiment was undertaken to evaluate the food preference of Stethorus gilvifrons (Muls.) on deferent stages of the spider mite Tetranychus urticae Kock.The influence of prey stages on the biological performance of predator was also evaluated .Results showed that the predator larvae preferred the egg of over others stages, while adult mite were the least preferred host .Females of the predator preferred mite larvae in the first place followed by egg and then other stages subsequently. Males preferred mite eggs followed by other subsequent stages. The prey consumption time by predator larvae increased with the increasing size of prey and decreased with increase of the predator developmental stages. First and fourth instars larvae needed an average of 2.1 and 0.5 minutes to consume an egg of mite. The same predator stage needed an average of 11.8 and5.4 minutes respectively to consume adult mite. Results also indicated that the shortest developmental period and the highest survival rate were 10.2 days and 94.1% respectively obtained when the predator fed on mixed stages of mites. The longest period and lowest survival rate were 18.9day and 85.6% recorded for larvae fed on mixed stages of egg and adult mites. The biological performance of the predator adults was also improved when fed on diet containing mixed stages of mites.