Harmonia axyridis Pallas (Coleoptera: Coccinellidae): Biological aspects and thermal requirements

Abstract

The aim of this study was to determine the biological aspects and thermal requirements of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) fed daily with Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs. Under laboratory conditions, the experiment was carried out in acclimatized chambers set to 18˚C, 21˚C, 24˚C, 27˚C, and 30˚C. Larvae of H. axyridis were separated, kept in a glass tube, and fed with A. kuehniella eggs. The Asiatic lady beetle adults were separated into 20 couples and kept in plastic cups receiving the same food as the larvae. The length of the larval, pupal, and total biological cycle (from egg to adult) stages declined significantly from 18˚C to 27˚C, but were stable between 27˚C and 30˚C. Survival was similar for larvae from the first to the fourth stadium when kept at 18˚C, 21˚C, and 24˚C with a higher total biological cycle survival at 27˚C. H. axyridis males presented higher longevity at 18˚C and 21˚C in comparison to females that had a longer life and a higher fecundity at 24˚C and 27˚C, respectively. The lower thermal limit for biological cycle development was 12.4˚C, and the thermal constant was 243.9 degree-days.