Date of Award:
5-1-1997
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Biology
Committee Chair(s)
Frank J. Messina
Committee
Frank J. Messina
Committee
Edward W. Evans
Committee
Edmund D. Brodie Jr.
Abstract
This research investigated the effects of plant architecture on the foraging behavior and prey capture success of two generalist predators of the Russian wheat aphid, Diuraphis noxia (Mordvilko). One study examined plant architectural effects on the behavior of a native predator, the common green lacewing, Chrysoperla plorabunda Fitch; a second study examined host plant effects on larvae and adults of the fourteen-spotted ladybird beetle, Propylea quatuordecimpunctata (L.), which is native to Eurasia and has been released in the United States for potential control of D. noxia. Behavioral observations of each of these predators were conducted on two architecturally diverse perennial grasses, crested wheatgrass, Agropyron desertorum (Fisher ex Link) Schultes, which is characterized by flat, broad leaves and a spike inflorescence, and Indian ricegrass, Oryzopsis hymenoides (Roemer & Schultes) Ricker, which is characterized by linear, involute leaves and a panicle inflorescence. In the absence of aphid prey, both lacewing and ladybeetle time budgets and residence times were similar on the two host grasses. On plants infested with the Russian wheat aphid, the number of aphids dislodged, contacted, and captured by predators was significantly higher on Indian ricegrass than on crested wheatgrass. On crested wheatgrass, aphids frequently occurred in relatively concealed locations, such as the rolls of immature leaves or the blade-sheath junctions of mature leaves; leaves of Indian ricegrass were usually so tightly rolled that a large fraction of the aphid population was forced to feed in more exposed locations. Comparisons of predator behavior on aphid-free versus aphid-infested plants suggest that plant architecture modified prey susceptibility primarily by its effect on prey accessibility rather than by its effect on predator movement. Although both predators were more effective at locating and capturing prey on Indian ricegrass, lacewing larvae were better able to feed on aphids in refuges by virtue of their sickle-like mandibles; fourth-instar larvae and adult ladybeetles were largely excluded from refuges of crested wheatgrass. These results suggest that lacewings may be an effective biological control agent against the Russian wheat aphid on cereals, which are structurally more similar to crested wheatgrass than to Indian ricegrass.
Recommended Citation
Clark, Teresa L., "Effects of Plant Architecture on the Foraging Behavior and Prey Capture Success of Two Generalist Predators Attacking the Russian Wheat Aphid" (1997). Biology. 636.
https://digitalcommons.usu.edu/etd_biology/636
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