When good bugs go bad: intraguild predation by Jalysus wickhami on the parasitoid, Cotesia congregata

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.

The parasitic wasp Cotesia congregata uses multiple mechanisms to control host (Manduca sexta) behaviour

“…The localized desensitization is temporary, however. Within a day, the caterpillar's defensive strike recovers and it becomes a bodyguard for the cocoons (Kester and Jackson, 1996). Manduca sexta can also kill the wasps by eating the cocoons (Adamo et al, 1997); therefore, suppression of host feeding is critical for successful wasp development.…”

“…However, these parasitoids lose the opportunity to use the host as a bodyguard (Harvey and Malcicka, 2016) during the parasitoid's vulnerable pupal stage (e.g. Kester and Jackson, 1996). Even among wasp parasitoids from the same genus, the host's post-emergent behaviour can vary (Harvey et al, 2008).…”

“…Why caterpillars do not strike at the emerging wasps remains unknown; we examined this issue in this paper. After the wasps emerge, the caterpillar host becomes the cocoons' bodyguard (Kester and Jackson, 1996), as is seen in other parasitoid systems (e.g. Grosman et al, 2008;Harvey et al, 2011).…”

“…(A parasitoid is an insect that develops by feeding off the body of another arthropod; Godfray, 1994.) The host can live for up to 2 weeks after wasp emergence; however, the caterpillar ultimately succumbs to starvation (Kester and Jackson, 1996).…”

Interspecific interaction between Telenomus remus (Hymenoptera: Platygastridae) and Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) on Spodoptera frugiperda (Lepidoptera: Noctuidae) eggs

“…Prior to an introduction or release of natural enemies, such interactions should be well characterized and carefully studied, since various aspects may interfere with the action of biological control agents (Kester and Jackson 1996, Vilela and Pallini 2002, Babendreier et al 2003, Arim and Jaksic 2005. Researchers have traditionally worked on elucidating only the association between a prey and one (or very few) predator or parasitoid species (Rosenheim et al 1995).…”