New approaches to quality control for cultures of insects for rearing

Abstract

An analytical review of existing methods of quality control for cultures of insects for rearing is presented. It is shown that there is a need to search for new approaches to solving this problem. The suggested methods for quality control for insect cultures are based on the rule of taxis intensity dependence on insect viability level. Testing of new methods of control and prediction of biological material viability was carried out on several breeds of silkworm (Bombyx mori L.) and a laboratory culture of the gypsy moth (Lymantria dispar L.). It was established that the caterpillars of silkworm breeds with high viability show higher chemotaxis intensity. It was found that intensity of taxis manifestation can be considered as a criterion of population condition. Selection of the most promising breeds of silkworm can be carried out at the moment of hatching without expensive rearing. It was shown that testing of neonate caterpillars by chemotaxis intensity provides the control of viability in all stages of insect development. Evaluation of chemotaxis intensity of adult males on female sex pheromone gives the possibility to select the specimens with the highest physiological properties for hybridization as well as to predict viability for progeny. The method of biological material selection by chemotaxis intensity was improved due to decrease the time of selection from 30 to 15 minutes and preliminary starvation of these insects. Positive correlation was evaluated between general viability of silkworm culture and intensity of chemotaxis of neonate larvae to the smell of mulberry leaf during 15 minutes after 12 hours of starvation. A significant increase of viability for silkworm breeds and hybrids was registered using such selection method during the spring and summer rearing. This selection method can be used also for assessment of culture viability. A new express-method of biological material selection for insect cultures establishment has been approbated. It is based on the positive correlation between insect viability parameters and their trophotaxis intensity. It is shown that for establishment of a laboratory culture of gypsy moth it is necessary to obtain the material from populations with the highest chemotaxis intensity. It was experimentally proved that parameters of chemotaxis intensity and insect viability reflect a certain level of population heterozygosity. The higher is the intensity of chemotaxis, the higher is the relative level of population heterozygosity. This fact gives the possibility to determine the level of heterozygosity for artificial insect populations by testing larvae for chemotaxis intensity. This method may be suitable for monitoring of natural populations condition in zones with intensive anthropogenic loading.