The photoperiodic regulation of the larval growth and pupation in the mealworm beetle, Tenebrio molitor L. (Coleoptera, Tenebrionidae)


Tyshchenko, VP.; Amadau Sheik Ba.

Entomologicheskoe Obozrenie 65(1): 3-12

1986


The life cycle of Tenebrio molitor is controlled by two-top curves of photoperiodic reaction (PhPR), which influences the rates of larval growth and pupation. At 20 and 25.degree. the day length has similar effects on growth and pupation, but the photoperiodic regulation of growth is weakly defined and it is not indispensable condition for photoperiodic regulation of pupation. The most stable character of PhPR is a sharp transition from the strong inhibition of pupation to its stimulation, when the day length is extended from 10 to 12 hours. Not only the initiation of pupation delays but also its longevity is controlled by PhPR. At 25.degree. 12-hour day induces the pupation of 100% larvae without delays. Long days give rise to more protracted delays than short days. When the temperature increases to 30.degree., the inversion of photoperiodic response appears and 12-hour day inhibits pupation, while long day (18-hour) and continuous illumination stimulate formation of the pupae.