Interaction Network and Niche Analysis of Natural Enemy Communities and their Host Bees (Hymenoptera: Apoidea) in fragments of Cerrado and Atlantic Forest

Reinanda Lima,Diego Moure Oliveira,Carlos Alberto Garófalo

doi:10.13102/sociobiology.v65i4.3386

Reinanda Lima, Diego Moure Oliveira + Show 1 more

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https://doi.org/10.13102/sociobiology.v65i4.3386

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Journal: Sociobiology	Publication Date: Oct 11, 2018
Citations: 3	License type: cc-by

Affiliation: Universidade de São Paulo

Abstract

Natural enemies are important components of solitary bee communities that nest in preexisting cavities because they act as a relevant mortality factor and can regulate population growth. Despite this, the natural enemy-host interaction remains poorly investigated. This research aimed to determine the composition of the community, the structure of the interaction network, and niche overlap and breadth of natural enemy species in areas of Cerrado (Brazilian savanna) and Semideciduous seasonal forest (Atlantic Forest) in the state of São Paulo, Brazil. Trap-nests made of black cardboard and bamboo canes were provided in the field and inspected monthly in each area, from August 2001 to July 2003 at Cerrado and from June 2006 to May 2008 at the Semideciduous seasonal forest. A modular structure in the interaction network was observed for both areas with the populations of natural enemies showing high degrees of specialization. This structure confers higher stability against disturbances than less specialized webs since these adversities must spread more slowly through the network. The niche analysis showed low degrees of overlap for both, trophic and temporal, among the natural enemy populations.

Highlights

Of the approximately 20,000 known species of bees more than 85% are not social but solitary (Batra, 1984) and among the solitary bees, 5% of them are species that nest in preformed cavities (Krombein, 1967; Batra, 1984)
A better knowledge of factors driving the population dynamics of solitary bees is essential for the future conservation of suitable habitats and ecological interactions (Kearns et al, 1998)
During the period of study, we found asymmetry in the phenology of the natural enemy species, as in 2003 when only Coelioxoides exulans (Holmberg) was sampled (Fig 1)

Summary

Introduction

Of the approximately 20,000 known species of bees more than 85% are not social but solitary (Batra, 1984) and among the solitary bees, 5% of them are species that nest in preformed cavities (Krombein, 1967; Batra, 1984). The abundance of many bee species has been declining for a variety of reasons, including agricultural intensification, which includes the loss of natural habitats, agricultural practices, floral resource availability and, increased pesticide and herbicide use (Potts et al, 2010). This decline of species diversity has been shown to result in productivity decrease in many ecosystems (Tilman et al, 2001) while the diverse pollinator communities provide more stable and productive ecosystem services (Rogers et al, 2014). Bottom-up factors mainly act as density-independent factors that limit population growth while top-down factors, i.e., natural enemies, can regulate population dynamics by positive density-dependent parasitism or predation (Berryman, 2001)

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