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United States Department of Agriculture

Agricultural Research Service

Research Project: Biologically Based Management of Invasive Insect Pests and Weeds

Location: Insect Behavior and Biocontrol Research

Title: Host specificity and risk assessment of Trichogramma fuentesi (Hymenoptera:Trichogrammatidae), a potential biological agent of Cactoblastis cactorum (Lepidoptera: Pyralidae)

item Paraiso, Oulimathe
item Hight, Stephen
item Kairo, Moses T.k.
item Bloem, Stephanie

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2013
Publication Date: 12/1/2013
Citation: Paraiso, O., Hight, S.D., Kairo, M., Bloem, S. 2013. Host specificity and risk assessment of Trichogramma fuentesi (Hymenoptera:Trichogrammatidae), a potential biological agent of Cactoblastis cactorum (Lepidoptera: Pyralidae) . Florida Entomologist. 96(4):1305-1310.

Interpretive Summary: A moth from Argentine whose caterpillars feed on prickly pear cactus became established in Florida. The continued spread of this cactus moth has raised concerns about this insect’s unavoidable and unwanted impact on native, agricultural, and ornamental cactus in its new homeland. A tiny wasp was found in Florida that attacks the eggs of this cactus moth by laying her eggs inside the cactus moth eggs. Scientists with USDA, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida, Animal and Plant Health Inspection Service, and Florida Department of Plant Industry are looking into ways to control the cactus moth, including natural enemies such as the egg-attacking wasp. Studies were conducted to assess the suitability of native Florida butterflies and moths to the wasp. The proportion of native insect eggs attacked by the wasp was higher than the proportion of Argentine cactus moth eggs attacked. This high attack rate of native species makes this wasp an undesirable natural enemy of the invasive cactus moth and will not be pursued as a control agent for this pest.

Technical Abstract: Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) is a non-native moth attacking prickly pear cactus, Opuntia spp., in southeastern U.S. The insect is also an important threat to ecological systems and to native and endangered Opuntia spp. in southwestern USA. The egg parasitoid Trichogramma fuentesi Torre (Hymenoptera: Trichogrammatidae) was discovered attacking wild C. cactorum in Florida. To evaluate the potential effect of inundative releases of T. fuentesi against C. cactorum, the host searching behavior of T. fuentesi on C. cactorum eggs and host suitability of selected lepidopteran eggs were studied in the laboratory. Host suitability was studied on the native blue cactus moth, Melitara prodenialis Walker, and 6 selected species of butterfly eggs [Danaus plexippus (L.), Dryas iulia (Hübner), Junonia coenia (Hübner), Papilio glaucus (L.), Papilio polyxenes (F.), and Vanessa cardui (L.)] to assess the potential for non-target effects from T. fuentesi. The proportion of parasitism of the native cactus moth (M. prodenialis) was 98%; significantly higher than the non-native cactus moth, C. cactorum (11% average parasitism rate). The high proportion of parasitism for all native non-target species tested and the lowest proportion of parasitism for the exotic target species suggested that T. fuentesi not be considered for inundative releases in a biological control approach against C. cactorum.

Last Modified: 10/18/2017
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