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When good bugs go bad: intraguild predation by Jalysus wickhami on the parasitoid, Cotesia congregata
Author(s) -
Kester Karen M.,
Jackson D. Michael
Publication year - 1996
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1046/j.1570-7458.1996.00096.x
Subject(s) - biology , parasitoid , intraguild predation , pupa , predation , braconidae , zoology , biological pest control , hymenoptera , predator , ecology , larva
We report a case of direct intraguild predation involving an insect predator and parasitoid in an agricultural system. The spined stilt bug, Jalysus wickhami Van Duzee, feeds on eggs of the tobacco hornworm, Manduca sexta L., and also on prepupal and pupal stages of the gregarious hornworm parasitoid, Cotesia congregata (Say). In two separate trials, mean mortality of attached parasitoids was significantly lower (66%, 73%) than that of their detached siblings (97%, 96%) after a 3 day exposure to stilt bugs, demonstrating that attachment to the host offered some protection against predation. In no‐choice experiments, prepupal parasitoids suffered greater mortality (0 day‐old = 61%, 1 day‐old = 65%) than pupal parasitoids (2 day‐old = 50%, 3 day‐old = 14%). When offered in combination with 0 or 2 day‐old hornworm eggs, respective mortality of 0,1,2 and 3‐day‐old pupal parasitoids showed a similar pattern (67%, 63%, 33% and 23%). In another experiment, mortality of 0‐day‐old pupal parasitoids (64%) was greater than that of 3 day‐old pupal parasitoids (38%). Mortality of pupal parasitoids was not affected by the availability of hornworm eggs, a highly acceptable food. Younger pupal parasitoids (= prepupae) probably suffered greater mortality because they were more easily fed on by stily bugs than older (pupated) ones. Because C. congregata overwinters in the prepupal stage, it may be particularly vulnerable to attack late in the season when stilt bug populations are large and hornworm eggs are relatively uncommon.