Laboratory studies on the suitability of Thrips tabaci Lindeman (Thysanoptera, Thripidae) as prey for the development, longevity, reproduction and predation of four predatory mite species of the genus Amblyseius (Acari, Phytoseiidae)

In the present study, the suitability of Thrips tabaci Lindeman (Thysanopte ra, Thripidae) larvae as prey of the predatory mites Amblyseius (Iphiseius) degenerans Berlese, Amblyseius umbraticus Chant, Amblyseius andersoni Chan t and Amblyseius limonicus Carman and McGregor was examined under laborator y conditions. The spider mire Tetranychus urticae Koch (Acari, Tetranychida e), standard prey in rearing predatory mites, was used as comparative prey. The suitability of T. tabaci as prey for the development, longevity, repro duction, and predation of the predatory mites was determined. Since the oni on thrips is the most important economic pest in the field production of le ek (Allium porrum L.) in Germany, the results of this study should provide information on the potential of these predatory mites as biological control agents. Results showed that I: tabaci larvae as prey had a negative influe nce on the examined parameters of most: predatory mite species when compare d with T. urticae as control prey. A. degenerans was not able to develop be yond the protonymph stage with thrips lan ae being the only prey available. Longevity of A. umbraticus and A. limonicus was reduced to half and one th ird, respectively. Daily and total reproductive rates were reduced for all four predatory mite species examined. A. andersoni tvas the only predatory mite that showed comparable results when fed with T. tabaci. Its total deve lopmental time was not prolonged significantly and longevity was only reduc ed by a few clays. Furthermore, A. andersoni showed the highest mean lifeti me predation rare of all examined species amounting to 35 T. tabaci-larvae. How well these predatory mites will actually perform in biological control of T. tabaci in the field cannot yet: be concluded from the assessed labor atory potential and has to be evaluated in the field.