Discrimination of the Palomena prasina L. (Heteroptera: Pentatomidae) nymph stages and sex using some morphological parameters by the multiple regression analysis

Abstract

Discrimination of different nymphal stages and sex (male and female) of insects is important in the morphological, physiological and toxicological studies under laboratory and field conditions. The morphometric study of different parts of an insect’s body is needed to obtain an index to distinguish between different nymphal stages and sex. In the hazelnut production area of the Black Sea region, amongst the sucking type bugs the green shield bug (Palomena prasina L.) is the most important specie encountered due to its intensity and economical damage threshold. The study was aimed to develop modeling of the P. prasina nymph stages and sex (NSS) using body length and prothorax width. Eight regression equations were compared for accuracy and adaptability. The best model developed was as follows: NSS = 0.344 + 0.235W + 0.309L (R² = 0.9882), where NSS is nymph stages and sex, W is the prothorax width (cm) and L is the body length (cm). For validation of the model, estimated values for NSS showed strong agreement with the measured values. Therefore, it can be concluded that models presented herein may be useful for the estimation of the individual NSS with a high degree of accuracy.

Key words: Modeling, body length, prothorax width, Palomena prasina, nymph stages.