Effect of temperature and photoperiod on juvenile hormone biosynthesis and sexual maturation in the cotton bollworm, Helicoverpa armigera: implications for life history traits.

The Israeli population of the cotton bollworm, Helicoverpa armigera (Hübner), undergoes a short-day, low-temperature pupal diapause and is also suspected of being a seasonal migrant in the eastern Mediterranean region. H. armigera were reared in the laboratory under several constant temperature and photoperiodic combinations which simulate average conditions encountered in the spring, summer, early-autumn and late-autumn in Israel. Juvenile hormone (JH) biosynthesis, the onset of calling behavior, sex pheromone production and ovarian development were examined in virgin female moths subsequent to eclosion. Allatal maturation, defined as acquisition of competence to synthesize JH, was significantly delayed in moths reared under simulated spring conditions. This was probably the cause for the observed delay in ovarian development and the onset of calling behavior, and to the reduction in sex pheromone biosynthesis. The delay in female sexual maturation, commonly associated with migratory flight, is consistent with presumptive pre-reproductive migration in H. armigera.