ISSN:
1570-7458
Keywords:
intraguild predation
;
predation
;
Hemiptera
;
Jalysus wickhami
;
Cotesia congregata
;
Manduca sexta
;
tobacco
;
biological control
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00187035
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