Diapause in the phytoseiid mite, Neoseiulus (T.) fallacis

Abstract

Female Neoseiulus (Typhlodromus) fallacis exhibited an adult reproductive diapause. Induction of diapause was dependent upon both photoperiod and temperature. The critical photoperiod at 15·6°C occurred between 11·75 and 12·0 hr light/day for a strain collected at Brunswick, New Jersey and reared in the laboratory under long light periods for ca. 2 years prior to testing. When the F 1 progeny of a strain collected at Wilkesboro, North Carolina was reared under a 11·75 hr light/day, 15·6°C régime along with the New Brunswick strain the photoperiodic response of the two strains was similar. Further studies with the New Jersey strain showed that the incidence of diapause at a short light period was averted entirely at 26·7°C. Little difference was shown in the developmental rates of mites under a short and long light period. Diapause duration was reduced at 15·6°C by exposure to a long light period. When held constantly at a short light period, an increase in temperature from 21·1 to 26·7°C reduced the duration of diapause. This reduction may reflect an effect of temperature on diapause termination as well as post-diapause development. Although diapause termination was influenced by both photoperiod and temperature, it occurred eventually under all experimental conditions, including those initiating diapause. There was no significant parental effect on the incidence of diapause in F 1 and F 2 progeny of adults reared under either a short or long light period. However, parental preconditioning did alter diapause intensity. When parents and offspring experienced a short light period, the resulting diapause duration was significantly longer than when parents experienced a long light period and the offspring experienced a short light period.