Cannibalism of parasitoid-attacked conspecifics in a non-carnivorous caterpillar

• Published in: Entomologia experimentalis et applicata Vol. 151; no. 2; pp. 112 - 121
• Main Authors: Wang, Xin-Geng, Daane, Kent M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Blackwell Publishing Ltd 01.05.2014; Wiley Subscription Services, Inc
• Subjects: Braconidae; Choristoneura rosaceana; group selection; Habrobracon gelechiae; Hymenoptera; Lepidoptera; obliquebanded leafroller; Tortricidae; trans-generational defense
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1111/eea.12174

Cannibalism, the killing and consumption of conspecifics, can even occur in insect species typically considered to be non‐carnivorous. Of particular interest is the cannibalism of parasitoid‐attacked conspecifics, which could reduce parasitism levels in subsequent generations for that conspecific population. This study reports on the occurrence and some of the consequences of cannibalism in parasitoid‐attacked obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). We show that larvae of C. rosaceana, which is considered to be an herbivorous caterpillar species, did not prey upon live conspecifics, but readily consumed conspecifics attacked by Habrobracon gelechiae Ashmead (Hymenoptera: Braconidae). Further examination found that C. rosaceana larvae feeding on parasitoid‐attacked conspecifics, since their fourth instar, suffered a higher mortality and reduction in body size than those fed on plant material only. The cannibalism of attacked conspecifics did not appear to offer any nutrient benefits for the cannibal. To our best knowledge, this is the first empirical example of the occurrence and some of the consequences of cannibalism by a non‐carnivorous insect on its parasitoid‐attacked conspecifics. We discuss the adaptive significance of such cannibalism on parasitoid‐attacked conspecifics with respect to a trans‐generational fitness gain for the population through the killing of the parasitoids, thereby reducing parasitism in subsequent generations.