Figure 1.
A simple three-trophic level conceptual model based on the well-studied mechanistic linkages between cotton (Gossypium hirsutum), the herbivorous insect Helicoverpa zea, and the parasitic wasp Microplitis croceipes.
Solid blue arrows denote who eats whom, whereas dashed black arrows highlight ecological effects spanning non-adjacent trophic levels. Chemical structures represent caterpillar-induced cotton volatiles known to impact parasitoid foraging behavior, e.g., [29],[30]; from top to bottom: linalool, 3,7-dimethyl-1,3,6-octatriene, caryophyllene, and cis-3-hexen-1-ol. Photo credits: cotton, Charles T. Bryson, USDA-ARS, Bugwood.org; H. zea, Peggy Greb, USDA-ARS, Bugwood.org; Microplitis sp., James Lindsey, Ecology of Commanster.
Figure 2.
A food web depiction of feeding relationships associated with the caterpillar
The trophic diagram is based on direct field observations of predation events by W.H. Whitcomb and K. Bell in Arkansas (US) cotton fields during the 1950s and 1960s, and later reconstructed by [31]. Only a small subset of the carnivore community was included for ease of presentation and the food web thus represents a highly simplified view of trophic dynamics that naturally occur in this system. Photo credits: cotton, Charles T. Bryson, USDA-ARS; H. zea, Peggy Greb, USDA-ARS; jumping and lynx spiders and damsel bug, Joseph Berger; crab spider, Frank Peairs, Colorado State University; lady beetle, Scott Bauer, USDA-ARS; big-eyed bug and paper wasp, Russ Ottens, University of Georgia; assassin bug, Clemson University, USDA Cooperative Extension; praying mantis and robber fly, Whitney Cranshaw, Colorado State University; minute pirate bug, Bradley Higbee, Paramount Farming; mud dauber, used with permission from entomart (image available via www.entomart.be). All images (except for the mud dauber) are from Bugwood.org.