Attempt to define morphological parameters enabling sex determination of Ips typographus (Linaeus, 1758) (Coleoptera: Curculionidae: Scolytinae) using PCA and CLU

Abstract

There are only two known methods for determining the sex of Ips typographus (L.) – dissection that can­not be used with live beetles and by distinguishing between the density of the hairs on the head, a less reliable method that requires experienced personnel. As a result, we have sought to find a more reliable method of sex determination for I. typographus which can be used with live specimens but is still reliable and easy to conduct. The aim of the article is to explore the inner structure in data from measurements of morphological parameters of spruce bark beetles and to find correlations which could be used for sex determination. The number of beetles in our sample was 110, all from the first trapping of one pheromone trap. The statistical methods of principal components analysis (PCA) and cluster analysis (CLU) were used to support any correlation between the sex parameter and other morphological parameters (weight, elytra length, elytra width, pronotum length, pronotum width). As no correlation was found in the case of sex, we can claim that it is not possible to determine sex according to the examined morphological parameters. However, we have found an interesting inner structure in the data and it was confirmed that even weight is slightly correlated with other morphological parameters.