Anatomical and histological changes during dormancy in twococcinellidae

The gonads of both females and males ofSemiadalia undecimnotata Schneid, were studied during the estivo-hibernation period (August–May). The ovaries remain unripe in diapausing females, the ovarioles being formed by mere germaria until late April (or early May) when the previtellogenesis begins. In some years, the stage of the first oocyte is attained in females staying still in the hibernation quarters. On the contrary, both the spermatogenesis and spermateliosis proceed in the testes of diapausing males so long as the ambiant temperature is sufficiently high (August–September, April–May). Only in the coldest period of dormancy (November–March) the tissue of testicular follicles ceases to be active. Since mid-April the spermatogenesis and spermateliosis are resumed completely and the males fertilize the females, as is shown by dissections of their spermathecae. Seminal vesicles are always full of sperms. The digestive tract is empty in inactive coccinellids and the size of the fat body gradually diminishes in the course of estivo-hibernation.

The dependence of the activity of the tissue of testicular follicles on the ambient temperature was proved experimentally in bothS. undecimnotata andCoccinella septempunctata L. The temperature of +12°C enables a natural regression, while an abrupt transfer to +5°C renders gradual emptying of follicles impossible.