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Why Do Ladybirds Lay Eggs in Clusters?
B. K. Agarwala and A. F. G. Dixon
Functional Ecology
Vol. 7, No. 5 (Oct.,
1993), pp. 541-548
(article consists of 8 pages)
Stable URL:
http://www.jstor.org/stable/2390130
Functional Ecology © 1993 British
Ecological Society
Abstract
1. Hypotheses that have been proposed to account for egg
clustering in insects, and in particular the idea that it might be a defence
against predators, were tested using the two-spot and seven-spot ladybirds,
Adalia bipunctata and Coccinella septempunctata. 2. Clusters of eggs were not
more viable than single eggs and, when supplied with an abundance of food,
groups of larvae were not more viable and did not develop faster than single
larvae. 3. Clustered eggs were not less vulnerable to cannibalism than single
eggs. 4. Single eggs, however, were more likely to be eaten by predators than
eggs in clusters and predators were more strongly deterred from attacking
clusters than single eggs. 5. The strength of the deterrent effect associated
with mixed species egg clusters was a function of the proportion of
non-conspecific eggs in the cluster.
