Effects of defoliation by the edible caterpillar \u201cchitoumou\u201d (Cirina butyrospermi) on harvests of shea (Vitellaria paradoxa) and growth of maize (Zea mays)

Charlotte Payne,Fernand Bationo,Sally Pearson,Athanase Badolo,Andrew Balmford,Bakary Sagnon,Sioned Cox,Antoine Sanon

doi:10.1007/s10457-019-00385-5

Abstract

Edible insects are found in agricultural systems worldwide, and are an important source of food and income. However, many edible insects are also pests of important food crops, which raises the question of how far their presence might be costly to farmers in terms of reduced crop yields. In this study we aimed to understand the impact of defoliation of shea trees by edible caterpillars on yields of shea and maize in a mixed agroforestry system in Burkina Faso, West Africa. We collected field data in two consecutive years. Our results suggest that tree defoliation by caterpillars has no effect on shea fruit yields, and that defoliation may have a positive effect on maize productivity. We conclude that this appears to be an example of an agricultural system in which nutritionally and economically important plants and insects are both harvested by humans without risking yield reductions of harvested plants.

Highlights

Wild-harvested edible insects are an important source of food and income across much of the world (Van Huis et al 2013)
We found no significant difference in defoliation across compass directions, in either year of data collection
Despite highly variable levels of defoliation of shea trees by shea caterpillars, we found no evidence of that caterpillar herbivory impacts shea fruit production—variation among trees in the abundance of shea fruit was not correlated with variation in their extent of defoliation the previous year

Summary

Introduction

Wild-harvested edible insects are an important source of food and income across much of the world (Van Huis et al 2013). Edible insects are often harvested from agricultural systems In many cases, this is because insects that feed on crop plants are deliberately collected as food (DeFoliart 1992; Van Itterbeeck and Van Huis 2012). Some insects—such as grasshoppers and crickets—are collected at multiple points in the middle of their life cycle with the explicit aim of limiting crop damage This presumably means that the harvested biomass of insects is not maximised, but crop yield is higher than it would have been if the insects had been left to mature. Elsewhere farmers use insecticide to control outbreaks of these edible insects, apparently choosing higher crop yield over insect yield (Ecobichon 2001)

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