Bats Track and Exploit Changes in Insect Pest Populations

Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, United States of America.
PLoS ONE (Impact Factor: 3.23). 08/2012; 7(8):e43839. DOI: 10.1371/journal.pone.0043839
Source: PubMed


The role of bats or any generalist predator in suppressing prey populations depends on the predator's ability to track and exploit available prey. Using a qPCR fecal DNA assay, we document significant association between numbers of Brazilian free-tailed bats (Tadarida brasiliensis) consuming corn earworm (CEW) moths (Helicoverpa zea) and seasonal fluctuations in CEW populations. This result is consistent with earlier research linking the bats' diet to patterns of migration, abundance, and crop infestation by important insect pests. Here we confirm opportunistic feeding on one of the world's most destructive insects and support model estimates of the bats' ecosystem services. Regression analysis of CEW consumption versus the moth's abundance at four insect trapping sites further indicates that bats track local abundance of CEW within the regional landscape. Estimates of CEW gene copies in the feces of bats are not associated with seasonal or local patterns of CEW abundance, and results of captive feeding experiments indicate that our qPCR assay does not provide a direct measure of numbers or biomass of prey consumed. Our results support growing evidence for the role of generalist predators, and bats specifically, as agents for biological control and speak to the value of conserving indigenous generalist predators.

Download full-text


Available from: Paula Federico,
1 Follower
51 Reads
  • Source
    • "Several bat species feed on prey with varying habitat requirements throughout their lifespan, such as Plecotus sp. on moths (Alberdi et al., 2012; Razgour et al., 2011), Myotis myotis on coleoptera (Arlettaz, 1996), Myotis lucifugus on prey emerging from water habitats (Clare et al., 2011), Trachops cirrhous on frogs (Ryan et al., 1982). Other species hunt migratory prey originating in source habitats beyond the bats' home-range, such as Tadarida brasiliensis on migratory pest moths (McCracken et al., 2012), and N. lasiopterus on migratory passerine birds (Ibañez et al., 2001). This new perspective identifies as a risk factor any intensification or change in the land use that alters the habitats required by the prey at any life-stage or lifespan moment, even when the hunting grounds of the bats remain untouched. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Conservation efforts for endangered animals commonly focus on the protection of foraging habitats, aiming to ensure sufficient food availability. However, the diet of many species is based on animals that undergo habitat shifts across ontogenetic life stages, yielding considerable differences between the lifelong habitat requirements of both predator and prey. Consequently, prey availability may not only depend on the suitability of the foraging grounds where predator and prey coincide, but also on habitats where the ecological requirements of the non-prey stages are fulfilled. In this study we test to what extent prey of the insectivorous bat Rhinolophus euryale (Blasius 1853) originate either from the grounds where they are consumed, or in areas/habitats outside the bat's foraging sites. We analyzed the diet of R. euryale, by identifying its prey to the species level using DNA metabarcoding, and by searching for its prey's larval feeding requirements in the literature. We found that the larvae of the moth prey grow both inside and outside the grounds where they are hunted by the bats once the moths reach their adult stage. The importance of prey that originated from outside the bat's foraging grounds varied considerably across seasons. As a result, R. euryale does not only rely on the landscape elements where it hunts, but also on other source areas/habitats that supply it with food. This study shows that conservation measures that aim to address the foraging requirements of predatory species should not be limited to merely protecting their foraging grounds, but should also take into account the ecological requirements of their prey throughout their life stages.
    Biological Conservation 09/2015; 191:512–519. DOI:10.1016/j.biocon.2015.07.043 · 3.76 Impact Factor
    • "Quantification of biomass or abundance is highly desirable but remains illusive. Various attempts have been made to use qPCR (for example see McCracken et al. 2012), but these have seemed surprisingly complex. Early attempts based on equating sequence copy number with abundance are frequently suggested but there are significant controversies surrounding this concept (Pompanon et al. 2012, Clare 2014). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Competing hypotheses explaining species’ use of resources have been advanced. Resource limitations in habitat and/or food are factors that affect assemblages of species. These limitations could drive the evolution of morphological and/or behavioural specialization, permitting the coexistence of closely related species through resource partitioning and niche differentiation. Alternatively, when resources are unlimited, fluctuations in resources availability will cause concomitant shifts in resource use regardless of species identity. Here we used next generation sequencing to test these hypotheses and characterize the diversity, overlap and seasonal variation in the diet of three species of insectivorous bats of the genus Pteronotus. We identified 465 prey (MOTUs) in the guano of 192 individuals. Lepidoptera and Diptera represented the most consumed insect orders. Diet of bats exhibited a moderate level of overlap, with the highest value between P. parnellii and P. personatus in the wet season. We found higher dietary overlap between species during the same seasons than within any single species across seasons. This suggests that diets of the three species are driven more by prey availability than by any particular predator-specific characteristic. P. davyi and P. personatus increased their dietary breadth during the dry season, whereas P. parnellii diet was broader and had the highest effective number of prey species in all seasons. This supports the existence of dietary flexibility in generalist bats and dietary niche overlapping among groups of closely related species in highly seasonal ecosystems. Moreover, the abundance and availability of insect prey may drive the diet of insectivores.This article is protected by copyright. All rights reserved.
    Molecular Ecology 09/2015; 24(20):5296-5307. DOI:10.1111/mec.13386 · 6.49 Impact Factor
  • Source
    • "Bats are highly mobile predators, able to track spatiotemporal fluctuations in insect abundance (e.g. McCracken et al., 2012), which strongly decreases as management intensity increases (Wickramasinghe et al., 2004). Unfortunately, we do not have data on insect availability to empirically support this hypothesis. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Olive (Olea europaea L.) farming is one of the most widespread agricultural practice throughout the Mediterranean basin. Current trends even predict an increase in land area devoted to olive farms as well as the intensification of farming practices. However, knowledge of the effects of olive farming on animal species still remains elusive and conservation and management guidelines for the relevant stakeholders are therefore urgently needed. Here, we investigate community composition and activity patterns of insectivorous bats in Mediterranean olive monocultures in Southern Portugal. Bats surveys were carried out in three types of olive farms representing increasing levels of management intensity: (1) traditional olive farms, managed with few or no chemical inputs or manual labor; (2) semi-intensive olive farms, which share certain characteristics with traditional plantations, but are more intensively managed; (3) intensive olive farms, which are managed with high and frequent chemical inputs, and highly mechanized systems. We found differences in species richness and activity levels between farming practices. Both the number of species and foraging activity declined with increasing management intensity. However, olive groves as a whole showed a lower number of species compared with the regional species pool and extremely low activity levels, suggesting that large and homogeneous olive monocultures may serve more as commuting areas than true foraging habitats for bats. To our knowledge, this is the first study explicitly demonstrating the pervasive impact of olive farming on the community composition and activity levels of insectivorous bats. In the face of an even-increasing proportion of land surface devoted to olive farming in Mediterranean landscapes, our findings are therefore of great concern. We suggest that increasing habitat heterogeneity would contribute to preserve the community composition and ecological functionality of insectivorous bats in extensive olive monocultures.
    Animal Conservation 06/2015; DOI:10.1111/acv.12209 · 2.85 Impact Factor
Show more