Sympatric Bat Species Prey Opportunistically on a Major Moth Pest of Pecans

Elizabeth C Braun De Torrez,Gary F Mccracken,Veronica A Brown,Thomas H Kunz

doi:10.3390/su11226365

Elizabeth C Braun De Torrez, Gary F Mccracken + Show 2 more

Open Access

https://doi.org/10.3390/su11226365

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Abstract

Native predators provide undervalued pest suppression services to agriculture. Studies of pest consumption by insectivorous bats tend to focus upon single species in large, centralized colonies, while bats dispersed in small groups within the agricultural matrix often go unnoticed. Pecan trees, Carya illinoinensis, and the destructive pecan nut casebearer (PNC) moth, Acrobasis nuxvorella, comprise a tightly linked host–parasite system in a widespread agroecosystem native to North America. Here we use a quantitative polymerase chain reaction (qPCR) assay of fecal DNA to document predation on PNC moths by an assemblage of sympatric bat species across episodic peaks in PNC abundance. Although five species of bats consume PNC moths, greater predation by a solitary tree-roosting bat (eastern red bat, Lasiurus borealis) than other species is suggested by a higher frequency of PNC occurrence and quantity of PNC gene copies in fecal samples. Consumption of PNC by bats during all documented peaks in moth activity suggests that predation pressure occurs throughout the PNC season. Our results highlight the need to consider multi-species assemblages and different foraging strategies when assessing pest suppression services, particularly in agroforestry or tree crops. Assessing the diet of only common or easily captured species limits our ability to accurately document pest consumption by bats.

Highlights

Native predator assemblages provide critical but undervalued pest suppression services across agricultural landscapes worldwide [1,2]
Within the assemblage of bats that we investigated, our results suggest that eastern red bats are the primary bat predators of pecan nut casebearer (PNC) moths, with frequencies of PNC consumption two to ten times greater, and average PNC gene copy numbers two to three orders of magnitude higher, than for the other bat species examined
Our results indicate that the abundance of PNC moths relative to other available, prey-sized insects influences the likelihood of PNC consumption by bats, suggesting that the frequency with which PNC moths are encountered during foraging may be more important than the biomass, which takes into account the size and possible energetic reward of the prey

Summary

Introduction

Native predator assemblages provide critical but undervalued pest suppression services across agricultural landscapes worldwide [1,2]. The presence of these predators can help maintain insect populations at sustainable levels and dampen episodic outbreaks of destructive pests [3]. Because they do not depend upon a single species, assemblages of generalist predators are important pest regulators and suppressors in systems with complex food webs and diverse pest species [4]. Complementarity among multiple predators with different foraging strategies can enhance the efficacy of biological control in agricultural systems [10]

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