Egg cannibalism byColeomegilla maculata lengineonates: preference even in the presence of essential prey

Abstract

Abstract. 1. Egg cannibalism among coccinellids has been reported widely, however reasons why this type of behaviour is observed so frequently have been neglected. This experiment was undertaken to clarify whether cannibalistic behaviour is advantageous to Coleomegilla maculata lengi Thimberlake neonates and to understand the reasons for high levels of egg cannibalism.2. Benefits gained by neonate cannibals were ascertained by comparing survival, developmental time, and second-instar weight of C. maculata larvae that were allowed to cannibalise conspecific eggs or not. Preference and behaviour tests were also conducted to assess the reasons for high levels of egg cannibalism.3. Cannibal neonates grew faster and were heavier than non-cannibals. The developmental time of neonates was influenced more by prey vulnerability than by prey quality.4. In choice tests, where three different proportions of conspecific eggs and aphids were offered (33±67, 50±50, and 67±33%), C. maculata neonates always consumed significantly more eggs. Manly's preference indexes indicated that neonates showed a consistent preference for conspecific eggs.5. Seventy-five per cent of neonates observed went directly towards eggs and 90% of the first prey consumed by neonates were an egg. When aphids were painted with extract of crushed eggs and eggs with crushed aphids to determine whether neonates found eggs by chemical cues, neonates preferred aphids painted with egg extract to eggs painted with aphid extract.6. It was concluded that C. maculata neonates benefited from cannibalistic behaviour. Moreover, egg cannibalism is not related only to frequency of encounter; chemical cues are also involved in egg searching.

Egg cannibalism in Ascia monuste in the field; opportunistic, preferential and very frequent

“…It is generally assumed that eggs are highly nutritious, as they are provisioned by the mother with a yolk to feed the developing embryonic larva. Eggs could, therefore, be considered as a high quality food source that fits the nutritional requirements of neonates better than other diets (Eickwort 1973;Takahashi 1987;Hodek and Honek 1996;Gagnè et al 2002). Sometimes the survival of the 1st instar and its foraging success could be related to cannibalism (Banks 1956;Dixon 1959;Brown 1972;Kawai 1978), as this period is frequently critical and limiting for the larvae.…”

Cannibalism and Intraguild Predation Community Dynamics: Coexistence, Competitive Exclusion, and the Loss of Alternative Stable States

“…Search terms were "cannibalistic" or "cannibalism" combined with "preference," "choice," "heterospecific," "interspecific," "Manly's," and "Chesson." Empirical studies: Duelli (1981); Orr et al (1990); Leonardsson (1991); Streams (1992); Macpherson and Gordoa (1994); MacRae and Croft (1997); Baras et al (1999);Schausberger (1999); Walzer and Schausberger (1999) ;Gerber and Echternacht (2000); Schausberger and Croft (2000); Yasuda et al (2001); Gagné et al (2002); Santi et al (2003); Park et al (2005); Dörner et al (2007); Mahe et al (2007); Rudolf (2008); Byström et al (2013). nibalism on both complete diet shift and diet broadening LHIGP scenarios.…”

Food Relationships

“…Larvae of the coccidophagous ladybird Exochomus fl avipes generally developed faster when fed on conspecifi c eggs than when fed on their usual prey, Dactylopius opuntiae (Geyer 1947 ). Similarly, Col. maculata larvae gained more weight by preying on conspecifi c eggs than on aphids (Gagn é et al 2002 ). Agarwala and Dixon (1992) found that conspecifi c eggs of A. bipunctata were superior to aphids as food for fourth instars; consumption of a greater biomass of aphids was required to support a given rate of growth.…”