Persistence of deterrent larval tracks in Coccinella septempunctata, Cycloneda limbifer and Semiadalia undecimnotata (Coleoptera: Coccinellidae)

Abstract

The persistence of oviposition-deterring effects of coccinellid and chrysopid larval tracks on females of three aphidophagous coccinellid species was compared. One month old tracks of first instars of the coccinellid Cycloneda limbifer Casey deterred conspecific females from oviposition in choice tests with clean and contaminated substrates. Intraspecific effect of larval tracks in Semiadalia undecimnotata Schneider was statistically significant after 10 days. Although fresh tracks of conspecific first instars effectively deterred females in both tested populations of Coccinella septempunctata L., deterrent effects disappeared when tracks of larvae were only one day old. However, females of C. septempunctata laid fewer eggs on sites with 10 days old tracks of Chrysopa oculata Say or sites with one month old tracks of Chrysopa perla (L.) first instars than on clean sites. In contrast to females of C. septempunctata and S. undecimnotata, C. limbifer females left significantly more faecal spots on clean sites than on sites with 5-30 days old tracks of conspecific first instars. This indicates that sites with tracks of larvae can also effectively repel conspecific females of some coccinellid species from searching.