Comparative Study of the Antennae of Dendroctonus rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae): Sensilla Types, Distribution and Club Shape

Abstract

We compared the antennae of two sibling bark beetle species, Dendroctonus rhizophagus Thomas and Bright and Dendroctonus valens LeConte, to identify biologically and taxonomically relevant differences. Specifically, we characterized the diversity of sensilla types by using environmental scanning electron microscopy, quantified the abundance and distribution of the different types of sensilla on the antennal club, and characterized club shape through multivariate and geometric morphometric analyses. We identified four classes of sensilla in both species: chaetica, fluted, trichodea (three distinct types), and basiconica (long and short). ANOVA and MANOVA demonstrated that the number and distribution of sensilla with the potential for chemoreception (i.e., short and long basiconica) differed between species and sexes. Notably, the long sensilla basiconica in the third sensory band were clustered in D. rhizophagus but not in D.valens. Geometric morphometric analysis using 27 landmarks showed that antennal club shape differed significantly between the two species and was not correlated with antennal size. The shape differences were associated with the number and distribution of sensilla.

Illustrated Key to Species of Genus Dendroctonus (Coleoptera: Curculionidae) Occurring in Mexico and Central America

“…The antennae, elytra, seventh tergite, and genitalia of some specimens of the 13 species were removed. The structures were cleared, mounted and examined following the protocols described by López et al (2014) and Armendáriz-Toledano et al (2015) .…”

“…Terminology used for describing characters and states is adapted from Hopkins (1909) and Wood (1963 , 1982) for external adult morphology; Payne et al (1973) , Dickens and Paine (1977) , and López et al (2014) for antennal anatomy; and Cerezke (1964) and Armendáriz-Toledano et al ( 2014a,b , 2015 ) for morphology of male genitalia. Lastly, karyotype information and gallery patterns were obtained from the literature and field observations ( Lanier 1981 ; Wood 1982 ; Lanier et al 1988 ; Salinas-Moreno et al 1994 , 2010 ; Armendáriz-Toledano et al 2015 ).…”

New characters and redescription ofDendroctonus vitei(Coleoptera: Curculionidae: Scolytinae)

“…The presence of sensillae clustered into pit-craterlike cavities in the third and fourth antenomeres of D. vitei antennae is unique, and nothing similar has been documented in other species of Dendroctonus (Payne et al 1973;Dickens and Payne 1977;Chen et al 2010;López et al 2014). In addition, their occurrence in both sexes allows reliable differentiation of both male and female D. vitei from other species of the D. frontalis complex with which they can coexist in syntopy or sympatry.…”

Caracterización Morfológica de las Sensilas Antenales deRhyssomatus nigerrimus(Coleoptera: Curculionidae)

“…Este resultado coincide con el reportado por Smith et al (1976). López et al 2014 mencionan dos sensillas basicónicas diferenciadas en larga (10.3 μm de longitud y 2.4 μm de ancho) y corta (6.2 μm de longitud y 3 μm de ancho) ambas relacionadas con funciones quimiorreceptoras.…”