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© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Simple Summary

The cactus moth is from South America and feeds on prickly pear cacti (Opuntia sp.). However, it is now present in North America and threatening the native Opuntia plants there. We are investigating a potential biological control agent, the wasp Apanteles opuntiarum, as a sustainable method to control the cactus moth population. This wasp is a larval parasitoid. We studied several aspects of A. opuntiarum reproduction and laboratory rearing. We documented the morphology of the wasp eggs and larvae. We found that A. opuntiarum prefers to lay its eggs on previously parasitized larvae compared to unparasitized larvae. We also found that exposing cactus moth larvae without the cactus and in groups of 20 larvae resulted in the highest parasitism and produced the most wasp offspring, suggesting that these factors reduced defensive behaviors of the cactus moth larvae. Understanding the wasp’s preference for previously parasitized larvae and how the cactus moth larvae interact with their environment will allow us to manipulate these factors to improve wasp production in laboratory colonies. Efficient laboratory production will be critical for successful release of this wasp as a biological control for the invasive cactus moth.

Abstract

The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) is native to South America and has been used as a biocontrol agent of Opuntia (Cactaceae) in Australia and South Africa. Its invasion in North America has raised concerns for the native Opuntia in the USA and Mexico. We investigated the reproductive biology and rearing procedures of a host-specific potential biocontrol agent, Apanteles opuntiarum Martínez and Berta (Hymenoptera: Braconidae). Given the gregarious nature of the parasitoid larvae, we studied the morphology of the immature stages and evaluated evidence of polyembryony and superparasitism. We also investigated the effects of host exposure arena and host density on parasitism rates and wasp production. The morphological descriptions provide a basis for comparison with other species. Early larval instars of A. opuntiarum are similar to other microgastrine immature stages. However, the mature larva exhibits placoid sensilla in the epistomal region, a unique character not previously reported. We provide evidence that A. opuntiarum eggs are not polyembryonic; females frequently superparasitize and have an oviposition preference for larvae parasitized 1–2 d previously. Exposing larvae of C. cactorum to wasps while inside the cactus resulted in lower parasitism and fewer offspring from each host than exposing larvae in the arena without the cactus. Parasitism and mortality rates were higher at lower host densities, possibly due to reduced host group defensive behavior. These results suggest that preference for superparasitism, host defensive behavior, and interactions with the cactus may play an important role in per-host wasp production under laboratory conditions.

Details

Title
Reproductive Biology and Rearing Improvements of Apanteles opuntiarum, Potential Biocontrol Agent of the Argentine Cactus Moth, Cactoblastis cactorum
Author
Varone, Laura 1   VIAFID ORCID Logo  ; Benda, Nicole 2 ; Guala, Mariel Eugenia 3 ; Martínez, Juan José 4 ; Bruzzone, Octavio Augusto 5   VIAFID ORCID Logo 

 Fundación para el Estudio de Especies Invasivas, Hurlingham 1686, Buenos Aires, Argentina; [email protected]; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires 1033, Argentina; [email protected] (J.J.M.); 
 Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville, FL 32608, USA; [email protected] 
 Fundación para el Estudio de Especies Invasivas, Hurlingham 1686, Buenos Aires, Argentina; [email protected] 
 Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires 1033, Argentina; [email protected] (J.J.M.); ; Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Santa Rosa 7263, La Pampa, Argentina 
 Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires 1033, Argentina; [email protected] (J.J.M.); ; Instituto de Investigaciones Forestales y Agropecuarias Bariloche, Bariloche 8400, Río Negro, Argentina 
First page
604
Publication year
2024
Publication date
2024
Publisher
MDPI AG
e-ISSN
20754450
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3097949808
Copyright
© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.