Ecological Niche Modeling to Calculate Ideal Sites to Introduce a Natural Enemy: The Case of Apanteles opuntiarum (Hymenoptera: Braconidae) to Control Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America.

Stephen D. Hight,Saúl Espinosa-Zaragoza,Laura Varone,Nidia Bélgica Pérez-De la O,Víctor López-Martínez

doi:10.3390/insects11070454

Abstract

The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is an invasive species in North America where it threatens Opuntia native populations. The insect is expanding its distribution along the United States Gulf Coast. In the search for alternative strategies to reduce its impact, the introduction of a natural enemy, Apanteles opuntiarum Martínez and Berta (Hymenoptera: Braconidae), is being pursued as a biological control option. To identify promising areas to intentionally introduce A. opuntiarum for the control of C. cactorum, we estimated the overlap of fundamental ecological niches of the two species to predict their common geographic distributions using the BAM diagram. Models were based on native distributional data for both species, 19 bioclimatic variables, and the Maxent algorithm to calculate the environmental suitability of both species in North America. The environmental suitability of C. cactorum in North America was projected from Florida to Texas (United States) along the Gulf coastal areas, reaching Mexico in northern regions. Apanteles opuntiarum environmental suitability showed a substantial similarity with the calculations for C. cactorum in the United States. Intentional introductions of A. opuntiarum in the actual distribution areas of the cactus moth are predicted to be successful; A. opuntiarum will find its host in an environment conducive to its survival and dispersal.

Highlights

Mexico is one of the most rich and diverse areas of Cactaceae, with 850 species [1], many of them endemic to the region
Our ecological niche modeling study with C. cactorum and A. opuntiarum estimated the geographic space that could be occupied by these two species in a new region
We considered our projection of the C. cactorum ecological niche calculated in this study (Figure 2)

Summary

Introduction

Mexico is one of the most rich and diverse areas of Cactaceae, with 850 species [1], many of them endemic to the region. Opuntia spp., commonly referred to as prickly pear cacti, have long been used by native peoples as food for humans and animals, medicines, pigments, and fencing [3]. Insects 2020, 11, 454 economically important species of Opuntia for food is O. ficus-indica (L.) Mill., selected by indigenous people in central Mexico long ago as a vegetable (nopalitos) and a fruit (tunas) [4]. Many other edible species are used in Mexico, including O. megacantha Salm-Dyck, O. stricta Haw., O. dillenii (Ker Gawl.). Mexico leads the world in prickly pear cactus food production (74%) and is the principal consumer. The cultivated area of cactus fruits grew 940% from 1980 to 2015 [8]

Methods

Results

Discussion

Conclusion