Seasonal activity and environmental and hormonal regulation of development and diapause were studied in three different orders of tropical insects at Barro Colorado Island (9°N), Panama.
The seed bug, Jadera aeola, reproduces in the late dry season coincident with mass production of its food, seeds of Sapindaceae. Newly emerged adults enter diapause. Population density and food, but not photoperiod, appear to be involved in diapause regulation. Juvenile hormone analogue (JHA) stimulates sexual maturation in both sexes.
The fungus beetle, Stenotarsus rotundus, aggregates at the base of a palm tree where it remains in imaginal diapause for up to 10 months. In addition to daylength (Tanaka et al., 1987), humidity plays an important role in regulating diapause termination. Gonad and flight muscle development occur more rapidly at high humidity than at low humidity. Beetles treated with JHA initiate oocyte and flight muscle development but not testis development. 20-hydroxyecdysone has no effect on diapause termination.
Flesh flies (Sarcophagidae), when monitored with a meat-baited trap, show striking seasonal fluctuations in abundance. Yet, we found no evidence for diapause in three fly species reared in the laboratory under a range of photoperiod and temperature conditions.