Survival of stored and shipped Phytoseiulus persimilis predators for twospotted spider mite control in strawberry (Fragaria Xananassa duch.)

James F. Price, Elzie Mccord Jr., Dan E. Legard, Craig K. Chandler


Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) predators were shipped overnight on the day of their harvest from a commercial insectary in order to determine the effects of 4C storage at strawberry production sites in Florida. Beginning on the day of arrival and on each of the next 6 days, eight replicates of 5-ml samples were taken from a different bottle. Samples were placed in bottoms of 85 mm diameter×80 mm high cardboard ice cream containers and maintained at 27C in full laboratory light. Predators that reached tops of containers during each 5-minute interval were counted during 2 hours as a measure of dispersal fitness. Predators that did not reach the top were counted after 2 hours and were assumed poorly fit for dispersal. Concurrently, eight replicates of five apparently gravid females from the same source were caged to lay eggs for 5 days in order to determine average numbers of larvae produced per female per day. There was a positive linear response (Y = 2.718 + 3.886X) to days of storage in the portion of predators that failed to disperse in 2 hours. A positive quadratic response (Y = 12.131 - 0.480X + 0.292X) was observed in the time for 50% of the population to disperse. There was no significant effect of storage period on the average number of larval predators produced. Strawberry producers should release predators as quickly as possible, given that indicators of dispersal fitness decreased greatly after 5 days.


biological control; insects; integrated pest management; spider mites; storage; tetranychus urticae; acari; tetranychidae; phytoseiidae

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283