LEPIDOPTERAN EGG PARASITOID SURVEY OF O‘AHU: ASSESSING PARASITISM RATES AND PARASITOID DIVERSITY IN WILD COLLECTED AND SENTINEL EGGS ACROSS AN ELEVATION GRADIENT

Logan, Mitchel

LEPIDOPTERAN EGG PARASITOID SURVEY OF O‘AHU: ASSESSING PARASITISM RATES AND PARASITOID DIVERSITY IN WILD COLLECTED AND SENTINEL EGGS ACROSS AN ELEVATION GRADIENT

Files

Logan_hawii_0085O_10481.pdf (1.14 MB)

Date

2019

Authors

Logan, Mitchel

Advisor

Rubinoff, Daniel

Department

Entomology

Abstract

Egg parasitoids are mostly wasps and flies that oviposit into the eggs of other insects, which are used as a food source for the development of their larvae. They are often purposely employed to control pests in both agricultural and natural settings through the resulting reduction in the populations of targeted pest insects. Hawai‘i is known for its high levels of endemism among insects and plants in particular, but it also has some of the highest numbers of introduced species of arthropods in the world. Many of these introduced arthropods are parasitoids used to control populations of adventive insect pests. Egg parasitoids in particular are often used to target pest populations of Lepidoptera. Egg parasitoids are typically minute insects that are not readily detected during quarantine inspections, or during conventional insect collecting efforts. I summarized the history of egg parasitoid introductions in island systems no greater than 16,637 km2 and surveyed O‘ahu for unrecorded egg parasitoids by using sentinel eggs of three moths: Helicoverpa zea Boddie (Lepidoptera: Noctuidae), Daphnis nerii Linnaeus (Lepidoptera: Sphingidae) and Agrius cingulata Fabricius (Lepidoptera: Sphingidae) and eggs collected from wild populations of Lepidoptera across an elevation gradient on O‘ahu. To assess the effectiveness of sentinel eggs, and to detect egg parasitoid diversity, I also compared parasitism and parasitoid species between wild eggs and deployed sentinel eggs. In total 540 eggs were collected in the wild of which 319 (59.1%) were parasitized and 2,030 sentinel eggs were retrieved of which only 3.1% were parasitized; simple correlation coefficients were taken to compare percent parasitism, proximity to ports, and elevation between wild collected and sentinel eggs. My results reveal that parasitoid species differ by location, and wild collected eggs are parasitized at a higher rate than sentinel eggs, suggesting that such sentinels may not be effective measures of parasitoid impacts or diversity. A negative correlation was found for percent parasitism and proximity to ports in wild collected eggs, and both sentinel and wild collected eggs revealed a mild negative correlation between percent parasitism and elevation with parasitism decreasing at higher elevations. Four parasitoid species were collected in the survey of egg parasitoids on O‘ahu: Ooencyrtus pallidipes (Ashmead) (Hymenoptera: Encyrtidae), Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae), Telenomus sp. and an unidentified Eupelmid.

Keywords

Entomology, Conservation biology, Elevation, Hawai‘i, Lepidoptera, Parasitoid, Sentinel, Survey

URI

http://hdl.handle.net/10125/66215

Extent

95 pages

Rights

All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.

Collections

M.S. - Entomology

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