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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED MANAGEMENT STRATEGIES RELATED TO INSECTS FOR ESTABLISHED AND INVASIVE PEST SPECIES

Location: Crop Protection and Management Research

Title: Targets of an invasive species: Oviposition preference and larval performance of Cactoblastis cactorum on 14 North American Opuntioid cacti

Authors
item Jezorek, Heather -
item Stiling, Peter -
item Carpenter, James

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2010
Publication Date: December 1, 2010
Citation: Jezorek, H., Stiling, P., Carpenter, J.E. 2010. Targets of an invasive species: Oviposition preference and larval performance of Cactoblastis cactorum on 14 North American Opuntioid cacti. Environmental Entomology. 39(6):1884-1892.

Interpretive Summary: Cactoblastis cactorum, the cactus moth, is a well-known biological control agent for cactus species of the genus Opuntia. However, the arrival of the moth in Florida and its subsequent spread through the southeastern United States poses a threat to the diversity of these cacti in North America. Of particular concern are the ecological and economic impacts the moth could have in the cacti-rich southwestern United States and Mexico, where both native and cultivated Opuntia species are important resources. Although C. cactorum is known to attack many Opuntia species, there are many species in North America that it has not encountered. It is unknown which of these species would best support larval development if the moth were to spread further westward in North America. The objectives of this study were to determine if egg-laying females would demonstrate a preference for any of fourteen common Opuntia-like cacti native to or naturalized in Mexico and the southwestern United States; to determine which of these species would best support larval development; and to determine if female oviposition preference would correlate with larval performance, as predicted by simple adaptive models. Results from a field experiment showed that female moths preferred O. engelmannii var. linguiformis for oviposition, together with O. engelmannii var. engelmannii. Data analysis showed number of cladodes and degree of spininess to be significant predictors of oviposition activity. Results from a no-choice larval survival experiment showed Consolea rubescens to be the best host, together with O. streptacantha. The toughness of the outer layer of the cactus pad was found to be a significant predictor of larval development and survival. In general, oviposition preference was not correlated with larval performance. For example, despite being a preferred host for female moths, O. engelmannii var. linguiformis was not a good larval host; less than seven percent of larvae raised on this species survived to the adult stage. A lack of co-evolutionary history between C. cactorum and North American Opuntia-like species may have caused the disconnect between oviposition preference and larval performance.

Technical Abstract: Cactoblastis cactorum (Lepidoptera: Pyralidae), the cactus moth, is a well-known biological control agent for cactus species of the genus Opuntia. The arrival of the moth in Florida and its subsequent spread through the southeastern United States poses a threat to opuntioid diversity in North America. Of particular concern are the ecological and economic impacts the moth could have in the cacti-rich southwestern United States and Mexico, where both native and cultivated Opuntia species are important resources. Although C. cactorum is considered oligophagous, it is unknown which species would best support larval development if the moth were to spread further westward in North America. The objectives of this study were to determine if ovipositing females would demonstrate a preference for any of fourteen common opuntioids native to or naturalized in Mexico and the southwestern United States; to determine which of the fourteen opuntioids would best support larval development; and to determine if oviposition preference would correlate with larval performance, as predicted by simple adaptive models. Results from a field experiment showed that female moths preferred O. engelmannii var. linguiformis for oviposition, together with O. engelmannii var. engelmannii. A generalized linear model showed number of cladodes and degree of spininess to be significant predictors of oviposition activity. Results from a no-choice larval survival experiment showed Consolea rubescens to be the best host, together with O. streptacantha. Epidermal toughness was found to be a significant predictor of most larval fitness parameters. In general, oviposition preference was not correlated with larval performance. For example, despite being a preferred host for female moths, O. engelmannii var. linguiformis was not a good larval host; less than seven percent of larvae raised on this species survived to the adult stage. A lack of co-evolutionary history between C. cactorum and North American opuntioid species may have caused the disconnect between oviposition preference and larval performance.

Last Modified: 9/2/2014
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