Sensilla on the antennal flagellum of the sawyer beetles Monochamus notatus (Drury) and Monochamus scutellatus (Say) (Coleoptera: Cerambycidae)

Abstract

The antennae of the sawyer beetles Monochamus notatus and M. scutellatus were examined with the light and scanning electron microscopes to determine the types, number, distribution and innervation of the sense organs. Nine types of sensilla are described. Both short, thin-walled pegs (sensilla basiconica) and reversely curved thick-walled hairs (sensilla trichodea) are chemoreceptors. There are three types of long, thick-walled hairs (sensilla chaetica) which may be mechanoreceptors. One of these is modified in males to form unique snail-shaped pegs. A few domeshaped organs, probably campaniform sensilla, were found.In addition to sense organs, many glands occur in association with the sensilla, and the antennae are well supplied with dermal glands connected by canals to small pores on the surface.Throughout eastern Canada, wood borers of the genus Monochamus present the greatest single threat to softwood logs that must remain in the woods through the summer, and to standing trees killed by fires. Monochamus larvae are capable of boring into wood to a depth of nine inches or more (Gardiner, '57), and Raske and Safranyik ('70) estimate that as few as two or three of the resultant holes per square foot result in a 30 % downgrade in the value of lumber. The two economically important representatives of this genus found in New Brunswick are M . notatus (Drury), which breeds mainly in white pine (Pinus StTobus), and M . scutellatus (Say), which is less specific in its choice of host and can be found on several species of the Family Pinaceae. This work is part of a study of the sensory physiology of host attraction in these beetles.Several recent reviews deal with the structure and function of the receptors found on insect antennae (Slifer, '70; Schneider, '64; Lewis, '70) and a small body of literature with the receptors of various beetles. To date there is no work on receptors in cerambycids. MATERIALS AND METHODSSpecimens of both sexes of Monochamus J. MORPH., 146: 513-532. notatus and M . scutellatus were either collected in the field or raised in the laboratory in white pine logs (Pinus strobus). A small number of larvae were raised on an artificial diet (McMorran, '65) in order to obtain newly emerged animals with soft cuticle. Histological techniquesTwo approaches were made to obtaining serial sections of the heavily sclerotized cuticle. The most successful method consisted of softening the fixed antennae for four days in 30% hydrogen peroxide followed by double embedding in 2 % celloidin and Tissuemat using the method of Peterfi (Gray, '54). For harder blocks or thin sections, fixed antennae were embedded in plastics such as methacrylate (Pease, '60) and for serial sections some of the plastic blocks were trimmed closely and reembedded in Tissuemat. Stains used included Harris' hematoxylin and eosin, Mallory's triple stain (Gray, '64), osmium tetroxide and ethyl gallate (Wigglesworth, '57), and for methacrylate sections, 1 % toluidine blue (Pease, '60).To reveal permeable areas of the cuticle the crysta...

Antennal sensilla of the ground beetle Platynus dorsalis (Pontoppidan, 1763) (Coleoptera, carabidae)

“…Histological preparations stained with methylene blue showed one neurone per sensillum, which is characteristic to mechanoreceptive bristles. They could function with equal probability as sound, wind, or touch receptors in Monochamus (Dyer and Seabrook, 1975). In contrast, such very long mechanoreceptive bristles are absent on the antennae, for instance, of click beetles (Merivee, 1992;Merivee et al, 1998Merivee et al, , 1999.…”

Scanning electron microscopy of antennal sensible of Anoplistes halodendri halodendri and Anoplistes halodendri ephippium (Coleoptera: Cerambycidae)

“…Sensilla types of the two longicorn beetle subspecies are to some extent different from other longicorn beetles (Cheng et al, 2008;Hu et al, 2001;Zhuge et al, 2009Zhuge et al, -2010. For instance, the types of antennal sensilla of Monochamus notatu (Drury) and M. scutellatus (Say) (Dyer and Seabrook, 1975) of Monochamus are more various. In addition, the snail-shaped pegs and dome-shaped organs were not observed in this study.…”

“…The sensilla on the antennae, in particular, play a significant role on the detection of semiochemicals (Ma and Du, 2000). By analyzing different species of the same genus using scanning electron microscopy, we have found that both intra-and interspecific differences in the types, density, and distribution patterns of the antennal sensilla of many insects (Dyer and Seabrook, 1975;Huang et al, 2007;Li et al, 2000;Wang et al, 2007).…”

Antennal Morphology of Nacoliea octasema (Meyrick) (Lepidoptera: Pyralidae)

“…However, given the low numbers and positions of these sensilla on the flagellum of N. octasema, they may function as proprioreceptors, providing information on the relative positions of the flagellar segments. This function was ascribed to a type of chaetic sensillum in several species of beetle, for similar reasons (Dyer and Seabrook 1975;Dai and Honda 1990). Evidence for sexual dimorphism.…”

“…They occur at the edge of the exposed ventral strip, some among the scales. Chaetic sensilla are often mechanoreceptors Dai and Honda 1990) but some are contact chemoreceptors (Jefferson et al 1970) or auditory receptors (Dyer and Seabrook 1975). Type 1 chaetic sensilla of N. octasema are more abundant towards the distal end of the flagellum (Fig.…”