The biology and foraging behavior of the fairyfly parasitoid Anagrus delicatus (Hymenoptera: Mymaridae) were studied to determine their effect on host population dynamics and stability. Anagrus delicatus is a short-lived solitary parasitoid that attacks the egg stage of two geographically sympatric planthoppers, Prokelisia marginata and P. dolus (Homoptera: Delphacidae). Host eggs are laid within the leaves of the grass, Spartina alterniflora, found in salt-marshes of the Atlantic and Gulf coasts of the eastern United States. / Laboratory studies indicate that upon locating a patch (S. alterniflora leaves), A. delicatus quickly and efficiently detects the presence of host eggs. Wasps remain on a patch for up to ten hours, but numbers of hosts attacked are low and variable and not much affected by host density. This low attack rate is not a consequence of differences among host species, parasitoid egg limitation, long handling times, a high ratio of parasitized to unparasitized hosts, or the presence of a host refuge. However, direct interference among parasitoids does cause a decrease in number of attacks as wasp density per patch increases. These behaviors lead to density-independent parasitism among S. alterniflora leaves. / Field studies that measured the response of natural populations of A. delicatus to experimental host patches corroborate these laboratory findings. Per capita numbers of hosts parasitized are low, variable, and a declining function of parasitoid density (parasitoid interference); and result in spatial and temporal density independence. Wasps appear to favor a foraging strategy that serves to spread eggs among a number of host patches. / I examined these parasitoid behaviors for their effect on stability in traditional host-parasitoid models. In general, patch use by A. delicatus is not stabilizing, but parasitoid interference can greatly enhance or cause interaction stability. A model developed specifically for this system that incorporates both host and parasitoid biology and behavior supports this conclusion. Due to parasitoid interference and asynchrony in host and parasitoid generation times, this model predicts that A. delicatus will cause the host population to exhibit "stable" cycles through time; exactly the pattern found in nature. / Source: Dissertation Abstracts International, Volume: 52-10, Section: B, page: 5069. / Major Professor: Joseph Travis. / Thesis (Ph.D.)--The Florida State University, 1991.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76517 |
| Contributors | Cronin, James Thomas., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 239 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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