Dependence of the efficiency of activating and inhabiting thermophase from its position in photoperiod in the parasytic wasp, Alysia manducator Panz. (Hymenoptera, Braconidae)

摘要

Experiments were conducted at thermoperiods of 12-27 and 12-25 deg C. Thermophase coincided with 0-4, 4-8, 8-12, 12-16, 16-20, and 20-24 h of photoperiod. The time was recorded from the moment when light was turned on. Efficiency of the activation thermophase was compared at LD 12 : 12, LD 114 : 10 and LD 15 : 9. At LD 12 : 12, the thermophase was most efficient when coincided with 20-24 h of photoperiod. When thermophase coincided with 0-4, 4-8, 8-12, and 16-20 h at LD 12 : 12 all wasps (Alysia manducator Panz.) diapaused. Experiments conducted at LD 12 : 12 and constant 12 deg C have shown that the 《quality》 of diapause was different. In the same experiment, wasps were kept first 20 days at LD 12 : 12 and 6 different positions of thermophase, then they were removed in the constant darkness with the same thermorhythm. In all 6 positions of thermophase all wasps diapaused. The 《quality》 of diapause has proved to be almost identical when tested. This experiment shows that when photoperiodic signals are terminated, the new rhythm of the neurosecretory system is changed according to the thermorhythm. Combination of the thermophase with the first (12-16) or last 4 h (20-24 h) of the scotophase induced development without diapause in more than a half of the wasps. The diapause in 100% of the samples was observed when two thermophases coincided with 12-16 h and 20-24 h. These experiments support the hypothesis that two antagonistic centers regulate development of insects (Zaslavasky, 1984, 1988).