Extremely rapid maternal photoperiodic response in Trichogramma telengai: A fine-scale study

Timing of maternal photoperiodic response of Trichogramma telengai to a single long night was studied in lab-oratory experiments. Adult females reared under diapause-averting short night conditions (L:D = 18:6) experi-enced one diapause-inducing prolonged night (12 h) and then were allowed to lay eggs (to parasitize the host, Sitotroga cerealella, eggs) during 3 days. The progeny was incubated under moderately diapause-inducing con-ditions (14 degrees C in the dark). The maternal photoperiodic response was extremely rapid: a slight but statistically significant increase in the incidence of diapause was already observed in the progeny hatched from the eggs laid 8 h after the beginning of the 'additional' part of night. Such a quick photoperiodic response, as far as we know, has not been reported for any insect. Then the proportion of diapausing progeny gradually increased over 30-50 h reaching 85-95%. Control females developed and were kept as adults under short night (L:D = 18:6) condi-tions; diapause was induced in <10% of their progeny. Analysis of individual variations showed that the pro-portion of diapausing progeny of experimental females increased with time gradually (not abruptly). These data enriches our knowledge of insect photoperiodic response and can be used for the planning of further (in particular, molecular) studies.

Automated summary

The timing of maternal photoperiodic response of Trichogramma telengai to a single long night was investigated. The study found that the maternal photoperiodic response was extremely rapid, with a slight increase in diapause observed in the offspring hatched 8 hours after the start of the prolonged night. The percentage of diapausing progeny gradually increased over time, reaching 85-95% after 30-50 hours. These findings contribute to our understanding of insect photoperiodic response and have implications for future studies.