Effect of multiple mating on reproduction and longevity of the phytoseiid mite Neoseiulus californicus.

Females of some insects and mites that mate repeatedly (multiple-mated females) or that have limited food supply have a shortened life span, compared to females that are allowed to mate only once (single-mated females) or that have ample food. The present study focused on the relationship between mating frequency and various reproduction-related parameters in a commercial strain (Spical) of the phytoseiid mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The impetus for this study came from the previous finding that single-mated females displayed an extremely long postoviposition period (ca. 60 days), accounting for more than 75% of the total adult longevity. In the present study it was found that the postoviposition period in the multiple-mated females was shorter than in the single-mated females and that longevity was gradually shortened with increasing mating frequency. Total egg production in females that mated twice or more was higher than in single-mated females, but egg production did not increase further with more than two matings. Single- and multiple-mated females ceased oviposition on the 24th and 34th day of adult life, respectively; multiple-mated females produced only male progeny on and after the 30th day. The postoviposition period of multiple-mated females was 40% shorter than that of single-mated females. Yet, the postoviposition period of the multiple-mated females is still more than 30 days, suggesting that other factors besides mating frequency have an influence on the prolonged postoviposition period. The reproductive ability of the Spical strain females gradually decreased with increasing virgin period (i.e. with increasing age), but they did not lose their reproductive potential--not even when mating was delayed for more than 2 months (i.e. females remained virgin for 70 days).