Cryptic Species Discrimination in Western Pine Beetle, Dendroctonus brevicomis LeConte (Curculionidae: Scolytinae), Based on Morphological Characters and Geometric Morphometrics.

Jazmín García-Román,Francisco Armendáriz-Toledano,Gerardo Cuéllar-Rodríguez,Gerardo Zúñiga,Brian T Sullivan,José F Negrón,Moises Becerril,Osiris Valerio-Mendoza

doi:10.3390/insects10110377

Abstract

The western pine beetle (WPB), Dendroctonus brevicomis LeConte, is a major mortality agent of pines in North America. A total of 706 adults of WPB from 81 geographical sites were analyzed with traditional and geometric morphometric methods to evaluate the variation of discrete and quantitative morphological characters with particular attention to the antenna, spermatheca, and seminal rod. Principal coordinates and canonical variate analyses supported three geographical groups in WPB: (1) West, from British Columbia to southern California along the Pacific coast, Idaho, and Montana; (2) East-SMOC, including Nevada, Utah, Colorado, Arizona, New Mexico, Texas, Chihuahua, and Durango; and (3) SMOR, including Coahuila, Nuevo Leon, and Tamaulipas. The pubescence length on the elytral declivity was a robust character for separating West specimens from the other groups. Additionally, the genitalia shape both female and male in dorsal view was a reliable character for discriminating among groups. Based on these results, which agree with genetic and chemical ecology evidence, we herein reinstate Dendroctonus barberi Hopkins (East-SMOC group) and remove it from synonymy with D. brevicomis (West group). Differences in the spermatheca and seminal rod shape of SMOR specimens suggest that these populations might be a different species from D. barberi and D. brevicomis.

Highlights

The western pine beetle, Dendroctonus brevicomis LeConte, is a North American species distributed along the Pacific coast from southern British Columbia to southern California, in Idaho and easternInsects 2019, 10, 377; doi:10.3390/insects10110377 www.mdpi.com/journal/insectsMontana, and from Nevada, Utah, and Colorado southeast to Durango and Tamaulipas [1,2].Dendroctonus brevicomis is a facultative predator that, during outbreaks in Canada and the United States, colonizes and kills millions of trees, mainly ponderosa pine
Nevada; the second included specimens of the states adjacent to those of the west coast (Utah, Colorado, Arizona, New Mexico, and Texas), as well as those from Chihuahua and Durango states in the Sierra Madre Occidental (SMOC) in the North of Mexico (East-SMOC group); the third included specimens from Nuevo Leon, Coahuila, and Tamaulipas states in the Sierra Madre
Pairwise Hotelling’s vs. PCo2) partially recovered the same groups found in the analysis of sexes combined (Figure 4b), but with a slight overlapping between East-SMOC and SMOR groups

Summary

Introduction

The western pine beetle, Dendroctonus brevicomis LeConte, is a North American species distributed along the Pacific coast from southern British Columbia to southern California, in Idaho and easternInsects 2019, 10, 377; doi:10.3390/insects10110377 www.mdpi.com/journal/insectsMontana, and from Nevada, Utah, and Colorado southeast to Durango and Tamaulipas [1,2].Dendroctonus brevicomis is a facultative predator that, during outbreaks in Canada and the United States, colonizes and kills millions of trees, mainly ponderosa pine The western pine beetle, Dendroctonus brevicomis LeConte, is a North American species distributed along the Pacific coast from southern British Columbia to southern California, in Idaho and eastern. Dendroctonus brevicomis is a facultative predator that, during outbreaks in Canada and the United States, colonizes and kills millions of trees, mainly ponderosa pine In Mexico, D. brevicomis apparently does not produce outbreaks, its populations are far less abundant, and the insect colonizes a wider range of pine species, including. Ex Schltdl, P. durangensis Martínez, P. engelmannii Carr., P. leiophylla Schiede Ex Schltdl. & Cham., and P. teocote Schiede Ex Schltdl. Dendroctonus brevicomis is a member of the Dendroctonus frontalis species complex, which is composed of D. adjunctus

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