Prey Suitability of Galerucella pusilla Eggs for Two Generalist Predators, Coleomegilla maculata and Chrysoperla carnea

The leaf beetle, Galerucella pusilla, is an introduced natural enemy of purple loosestrife, Lythrum salicaria, in North America. The suitability of G. pusilla eggs for development and survival of Chrysoperla carnea and Coleomegilla maculata was quantified by measuring preimaginal development, survival, and adult weight. Individual first-instar predators were assigned to one of two diets: G. pusilla eggs or a diet of Ephestia kuehniella eggs and pea aphids (Acyrthosiphon pisum) alternated every 24 h. Chrysoperla carnea and C. maculata larvae that fed on G. pusilla eggs had lower survival rates, longer developmental times, and reduced adult weight. Galerucella pusilla eggs were not suitable prey for 95% of C. maculata larvae, but 37% of C. carnea larvae completed development on G. pusilla eggs. Because G. pusilla eggs may be utilized by these predatory species as alternative prey during periods of low availability of suitable prey, this predation could affect the biological control of L. salicaria.