Sexual dimorphism in body dimensions and antennal sensilla in the white grub beetle, Dasylepida ishigakiensis (Coleoptera: Scarabaeidae)

Abstract

The white grub beetle, Dasylepida ishigakiensis shows sex dimorphism in body dimensions and abundance of antennal sensilla. Body length was almost identical in the two sexes, but the abdomen was significantly longer in females than in males. Males had longer legs than females. Six types of sensilla were observed on antennal terminal lobes. The total number of sensilla on the inner surface of terminal antennal lobes was larger in males than in females. One type of sensilla showed a sex-specific size difference. Among individuals that were collected as third stadium larvae on Miyako Island, Okinawa, Japan and reared in the laboratory (nϭ527), three emerged as adults with asymmetrical antennae. One was found to represent a gynandromorph and the others were a male and a female with a deformed antenna.

Sexual dimorphism in antennal receptors of Phyllophaga ravida Blanchard (Coleoptera: Scarabaeoidea: Melolonthidae)

“…This morphological study of P. ravida receptors is the fi rst for melolontids with several different types of antennal sensilla. In similar studies, antennal lamellae of other species have a maximum of six sensilla types (Ochieng et al 2002, Romero-López et al 2004, Tanaka et al 2006. For Coleoptera Table 5 Measurements (μm) of sensilla type basiconica on lamellae of both sexes of Phyllophaga ravida.…”

“…This is evident in the antennae of several melolontid species, in which males have longer antennae than females (Morón 1986, Kim & Leal 2000, Tanaka et al 2006. As in P. obsoleta (Romero-López et al 2004), the antenna is sexually dimorphic in P. ravida: males have longer pedicel, fl agellum, lamellar club segments, and the entire antenna.…”

“…For example, both sexes of P. anxia and P. obsoleta have fi ve sensilla types (Ochieng et al 2002, Romero-López et al 2004. In other genera, there are cases in which a particular sex has two or three identical PLAS types, as in Phyllopherta horticola L. (Agren 1985), Adoryphorus couloni Burmeister (McQuillan & Semmens 1990), Anomala cuprea Hope (Leal & Mochizuki 1993), Phyllopherta diversa Waterhouse , and Dasylepida ishigakiensis Niijima & Kinoshita (Tanaka et al 2006). Results obtained for P. ravida are similar, although Table 4 Measurements of sensilla type auricilica on lamellae of both sexes of Phyllophaga ravida.…”

“…Previous records for others species use terminology and classifi cation based largely on Meinecke (1975) and Schneider (1964); these papers report the main sensilla types as placodea, basiconica, and coeloconica (Leal & Mochizuki 1993, Kim & Leal 2000, Baker & Monroe 2005, including the auricilic type (Ochieng et al 2002, Romero-López et al 2004. Some also use different nomenclatures: sensilla types I to VI for one species (Tanaka et al 2006) and placoid, basiconical, or trichoid sensilla types A, F, G, H, J, K, L for several species of Hoplia, Isonychus, Pelidnota, Callirhinus, Cotinis, Euphoria, Tomarus, and Aegidium (Carrillo-Ruiz & Morón 2008).…”

“…PLAS are the most common chemosensilla on male lamellae of melolontids and were reported to be involved in the chemical perception of sex pheromones (Leal & Mochizuki 1993, Romero-López et al 2004. Although AUS are traditionally classifi ed as a special type of PLAS , Tanaka et al 2006, they have been recently considered a separate type of sensillum and their participation in the perception of sex attractants is suggested (Ochieng et al 2002, Romero-López et al 2004.…”