Effect of temperature and photoperiod on the diapause of Doryctobracon areolatus under laboratory conditions

Abstract

Determine the effect of the temperature and photoperiod on the progeny of Doryctobracon areolatus was the main objective. The emergence, sex ratio and proportion of individuals that entered or broke diapause were recorded to understand how these factors influence the occurrence of diapause, and thus develop effective strategies to strengthen their lab rearing. Two temperatures (21 and 26 °C) and three photoperiod conditions (16: 08, 12: 12 and 08: 16, light: darkness hours) were evaluated under laboratory conditions. Both factors showed significant influence on the percent of adult emergence, the sex ratio, and the number of adults broking diapause. The proportion of the offspring entering diapause was lower than expected, which is associated to the high number of generations with strong selection of nondiapausal individuals in this strain over time. At the temperature of 26 °C, a greater adult emergence from diapausing pupa was recorded, which began to emerge two months after the start of diapause and continued until the eighth month. At 21 °C the emergence from diapausing pupa began at month five and continued for two more months, suggesting that lower temperature acted as a limiting factor for the continuation of the diapause. The effect of the photoperiod was less clear but was observed that the greatest rupture of diapause occurred in the 12: 12 h L: D ratio in both types of temperatures, and that the best proportion of females emerged in the ratio of 08: 16 h L: D. Our results suggest that the evaluated factors exert an effect on diapause breaking in D. areolatus, and that this could be related to its hosts phenology. This also provides a better support for an optimal management of environmental conditions in the process of their artificial rearing.