Temporal stability of morph frequency in central European populations of Adalia bipunctata and A. decempunctata (Coleoptera: Coccinellidae)

Alois HONĚK,Stano PEKÁR,Zdeňka MARTINKOVÁ

doi:10.14411/eje.2005.062

Abstract

In central Europe Adalia bipunctata (L.) occurs in two main colour morphs (typical, melanic), and A. decempunctata (L.) occurs in 3 morphs (spotted, chequered, dark). Temporal variation in the relative frequency of morphs was recorded in populations of the Czech Republic where geographic variation in morph frequency is low. Seasonal trends were investigated in samples collected by a light-trap run daily from March to November for 14 years. In A. bipunctata the melanic form was more abundant in autumn than in spring but the difference was not significant. In A. decempunctata morph proportions did not change seasonally. Samples were also collected by sweepnet from stands of many plant species. In both Adalia species the morph proportions did not differ significantly among collections made on different plants. Long-term changes in morph proportions were analysed by pooling annual samples over all host plants. In A. bipunctata, sampled in 15 years between 1971-2004, there was no significant change in proportion of typical (90.1%) and melanic (9.9%) forms. In A. decempunctata, sampled in 12 years between 1976-2004, the proportions of (mean over the years 29.4%), chequered (42.2%) and dark (21.3%) morphs varied between years. There was a trend toward an increasing proportion of the spotted form in the 2000s compared to the 1970s and 1980s.

Highlights

The enormous colour variation that occurs within some coccinellid species has attracted much research attention
Since we found no differences in morph proportions among samples collected from particular host plants, samples of all host plants taken in a particular year were pooled for testing the annual differences
The present study established the absence of significant variation among populations of different host plants and the absence of temporal variation in morph proportions

Summary

Introduction

The enormous colour variation that occurs within some coccinellid species has attracted much research attention. An important domain of investigation in this diversity is variation in proportion of colour morphs in local populations. These studies were pioneered by Dobzhansky (1933) who showed the relationship between climate and coloration in several coccinellid species. The morphs of each species were ranked according to the proportion of body surface that is dark, starting from the light (non-melanic) forms to the dark (melanic) forms. Data from Palearctic species revealed the prevalence of dark morphs in populations from humid and/or cold geographic areas and the dominance of light morphs in warm and dry areas

Methods

Results

Conclusion