Reproductive biology of selected populations of the seven-spotted lady beetle, Coccinella septempunctata (Coleoptera: Coccinellidae)

Abstract

The first goal of this research was to investigate aspects of the life history traits of selected geographic populations of C. septempunctata and to quantify differences that may describe distinct populations with local adaptations. Because C. septempunctata is widely distributed in its indigenous area, the source of the originally established populations in North America are not known. And recently, releases of C. septempunctata collected from several regions of Eurasia have been made against Diuraphis noxia, making it essential that the nature of the established populations of this lady beetle in North America be determined. That is whether it consists of homogeneous or heterogeneous populations with respect to local adaptations; and if it is heterogeneous, what characteristics are different among the populations. The information from such studies will ultimately help to determine populations that have attributes of an effective natural enemy, that is, ability to colonize or establish and to suppress insect pests. Such populations of C. septempunctata, when known, can be of use against newly invading insect pests, such as Diuraphis noxia, through redistribution from areas where they are found to the pest infested areas, and also in augmentation programs.

The second goal was to investigate the relationship between temperature and rate of the ovarian development in C. septempunctata. These relationships can be used to determine female reproductive age categories which in tum will allow inferences to be made about the age structure of C. septempunctata field populations. If the reproductive ages used in categorization of C. septempunctata populations can be converted to chronological ages, predictions can be made of changes in the age structure of a C. septempunctata population through time. Such predictions can be applied to assess the synchronization between predator and prey development and the efficiency of C. septempunctata in biological control.