Insect diversity in the Saharo-Arabian region: Revealing a little-studied fauna by DNA barcoding.

Joseph Addesi,Jamal S. M. Sabir,Arif M. Khan,Valerie Levesque-Beaudin,Muhammad Ashfaq,Carlene Gallant,Bernd Schierwater,Paul D. N. Hebert,Kate Perez,Akhtar Rasool,Hosam O. El-Ansary

doi:10.1371/journal.pone.0199965

Abstract

Although insects dominate the terrestrial fauna, sampling constraints and the poor taxonomic knowledge of many groups have limited assessments of their diversity. Passive sampling techniques and DNA-based species assignments now make it possible to overcome these barriers. For example, Malaise traps collect specimens with minimal intervention while the Barcode Index Number (BIN) system automates taxonomic assignments. The present study employs Malaise traps and DNA barcoding to extend understanding of insect diversity in one of the least known zoogeographic regions, the Saharo-Arabian. Insects were collected at four sites in three countries (Egypt, Pakistan, Saudi Arabia) by deploying Malaise traps. The collected specimens were analyzed by sequencing 658 bp of cytochrome oxidase I (DNA barcode) and assigning BINs on the Barcode of Life Data Systems. The year-long deployment of a Malaise trap in Pakistan and briefer placements at two Egyptian sites and at one in Saudi Arabia collected 53,092 specimens. They belonged to 17 insect orders with Diptera and Hymenoptera dominating the catch. Barcode sequences were recovered from 44,432 (84%) of the specimens, revealing the occurrence of 3,682 BINs belonging to 254 families. Many of these taxa were uncommon as 25% of the families and 50% of the BINs from Pakistan were only present in one sample. Family and BIN counts varied significantly through the year, but diversity indices did not. Although more than 10,000 specimens were analyzed from each nation, just 2% of BINs were shared by Pakistan and Saudi Arabia, 4% by Egypt and Pakistan, and 7% by Egypt and Saudi Arabia. The present study demonstrates how the BIN system can circumvent the barriers imposed by limited access to taxonomic specialists and by the fact that many insect species in the Saharo-Arabian region are undescribed.

Highlights

Because insects are the major component of terrestrial metazoan biodiversity and important indicators of environmental conditions [1,2], their biomonitoring can aid efforts to conserve and restore biodiversity [3], to evaluate the impacts of climate change [4], and to protect ecological services [5,6]
Aside from a lack of taxonomic resources, inaccessible terrain and political instability have contributed to the poor documentation of Saharo-Arabian biodiversity. This knowledge gap can be addressed by coupling efficient sampling methods, such as Malaise trap [33] with subsequent DNA barcode analysis to speed determinations of alpha and beta diversity and overlap [19]. By using this approach to examine patterns of insect diversity in Egypt, Pakistan, and Saudi Arabia, the present study provides a model for biodiversity surveillance in regions with limited previous biodiversity research
84% (44,432) of the specimens generated barcodes, sequence recovery varied among sites with the lowest recovery from Saudi Arabia (79%)

Summary

Introduction

Because insects are the major component of terrestrial metazoan biodiversity and important indicators of environmental conditions [1,2], their biomonitoring can aid efforts to conserve and restore biodiversity [3], to evaluate the impacts of climate change [4], and to protect ecological services [5,6]. Comprehensive assessments of their diversity have been impossible because of the lack of taxonomic specialists, and because many insect species are undescribed [7]. These barriers have contributed to the current uncertainty in the global species count [8] which can only be resolved by new approaches as morphological studies could require a millennium to inventory all species [9]. The capacity of DNA barcoding to advance understanding of biodiversity at local [12,13,14] and continental scales [15] is well-established. BINs are being used to advance biodiversity inventories [22], to reveal unknown faunas [23], and to explore biodiversity links among nations [24,25]

Methods

Results

Conclusion