On the identity of a U.S. intercepted Conotrachelus Dejean (Coleoptera: Curculionidae) with avocado (Persea americana)
Authors: Chamorro Maria Lourdes , Barclay Maxwell 
Published: November 2018

The multimillion-dollar avocado industry is threatened by a number of serious insect pests, including at least seven species of Curculionidae. Of these, threeConotrachelusspecies are known to develop and feed on avocados:Conotrachelus aguacataeBarber,Conotrachelus perseaeBarber andC. serpentinus(Klug); the first two are of economic importance. Recently, a series of unrecognisedConotracheluswas intercepted with avocado and other commodities by the USDA at various southern U.S. ports of entry. The species most closely resembled the U.S. nativeConotrachelus posticatusBoheman. Given the threat posed by certain species ofConotrachelusto avocado, the identity and biology of intercepted unknownConotrachelusspecies becomes a matter of much concern for regulators due to the potential risk posed by non-native species to local agriculture. This study aims to determine the identity, which in turn may shed light on the biology and native distribution, of possible new non-U.S.-native weevils and provide the tools necessary to distinguish amongst phenotypically similar native species.

Amongst the unknownConotrachelusweevils intercepted with avocados at certain U.S. ports of entry isConotrachelus lobatusChampion. This poorly known species resembles a commonly collected, phenotypically variable indigenous U.S. species,Conotrachelus posticatus, which, on occasion, is also intercepted with avocado.Conotrachelus lobatushas been collected, since the early 1900s until today, along a narrow corridor in the southwest Mexican states of Michoacan, Jalisco and Nayarit. Specimen label data in natural history collections suggests the presence of this species in large numbers in early July in the avocado growing region of Mexico and, based on notes from former curators, appears to breed in acorns of the Mexican endemic oak speciesQuercus obtusata. The interception ofC. posticatusandC. lobatuswth avocado does not imply strict biological association, however it reveals an important pattern of a non-native species' potential for introduction and its potential vector. Understanding all aspects of an organism's biology will better equip growers, as well as regulators, with effective and well-informed management strategies. Characters are imaged and discussed in order to help distinguish someConotrachelusspecies belonging toConotrachelusgroup II designated by Schoof (1942). Some characters of particular importance are the shape of the metauncus; shape of the lateral margin of the elytra and presence/absence of costate first and second elytral intervals. This study includes high-resolution images of sevenConotrachelusspecies, including the known avocado pestsC. aguacataeandC. perseae, as well as the first images ofC. lobatus,C. scopariusChampion andC. squamifronsChampion. The latter three species are not USA natives and were not included in Schoof's work. This study also confirms the important role played by natural history collections in anchoring the species' name through the study of types, which allows for the linking of biological and distribution data over time. Lectotypes are herein designated forC. lobatusandC. squamifrons.