S. Ya. Reznik and T. S. Kats

Exogenous and Endogenous Factors Inducing Diapause
in Trichogramma principium Sug. et Sor. (Hymenoptera,
Trichogrammatidae)

Entomological Review, Vol. 84, No. 9, 2004, pp. 963–970. 

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Maternal control of prepupal diapause in the progeny of the egg parasitoid Trichogramma principium Sug. et Sor. was studied in laboratory. Pre-maternal (G1) and maternal (G2) generations were reared at 20°C and photoperiods L : D = 3 : 21, 6 : 18, 9 : 15, 12 : 12, 15 : 9, 18 : 6, 21 : 3, or 24 : 0. The tendency to diapause in the progeny (G3) was determined by rearing at 13°C in the dark. The experiments revealed a response of a long-day type with a threshold zone of 12–15 h. The photoperiodic conditions of rearing of both G1 and G2 generations significantly influenced the prepupal diapause in the progeny (G3), the maternal influence being much stronger than the pre-maternal influence. Experiments with individual females which were offered several batches of host eggs demonstrated that the incidence of diapause in the progeny also depended on endogenous factors, such as the maternal age and duration of the egg retention period.