Ultrastructure of the larval antenna of Tenebrio molitor L. (Coleoptera: Tenebrionidae): structure of the trichoid and uniporous peg sensilla

Abstract

The antenna of the final instar larva of Tenebrio molitor has three segments. The reduced third (terminal) segment bears a large trichoid sensillum, four uniporous peg sensilla, one blunt tipped peg sensillum, and one papillate sensillum. The second segment bears a very large multiporous placoid sensillum, three uniporous peg sensilla, one blunt-tipped peg sensillum, and one papillate sensillum. The numbers and arrangement of these sensilla are usually stereotyped, but variations occur.The trichoid sensillum is a long, thin, unsocketed, aporous hair. It is innervated by two (sometimes one) bipolar neurones and has five sheath cells. The three sheath cells which distally delimit the large sensillar sinus have extremely elaborate microvillate inner borders. The uniporous peg sensillum is a short, stout, socketed peg with a single terminal pore. It is innervated by two to six (usually six) bipolar neurones. The dendrite from one of these always ends as a tubular body in the base, while the dendrites from the others extend to the tip of the peg. This sensillum has a small sensillar sinus and only four sheath cells. The inner sheath cell of both types of sensilla forms a cylindrical, nonlapped sleeve around the dendrite bundles.

Morphology of antennal, maxillary palp and labial palp sensilla in different larval instars of the Asian long‐horned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae)

“…are on the apices of the second and third segments (Zacharuk ; Scott and Zacharuk ; Behan and Ryan ; Bloom et al . ). The ALB (13) had the same total number of sensilla on the apex of the antenna as Tenebrio molitor (Coleoptera: Tenebrionidae) (13) (Bloom et al .…”

“…In T. molitor L. and M. melolontha , which were examined with transmission electron microscopy, the s.t.b.1 were possibly a mechanoreceptor as well as a gustatory chemoreceptor (Bloom et al . ; Eilers et al . ).…”

“…The ALB (13) had the same total number of sensilla on the apex of the antenna as Tenebrio molitor (Coleoptera: Tenebrionidae) (13) (Bloom et al . ), but higher numbers were found on Languria mozardi (Coleoptera: Languriidae) (22) (Baker and Ellsbury ) and Tribolium (Coleoptera: Tenebrionidae) (21) (Behan and Ryan ). The types of sensilla on the apices of the maxillary and labial palps of A. glabripennis were similar to those of other coleopterans.…”

“…) and Coleoptera, particularly on the coleopteran predators, such as the click beetles and the carabid beetles (Behan and Ryan ; Doane and Klingler ; Bloom et al . ; Baker and Ellsbury ; Giglio et al . ), and the phytophagous beetle, such as the Colorado beetle, white grub, red turnip beetle and alfalfa weevil (Mitchell and Schoonhoven ; Bland ; Baker and Monroe ; Farazmand and Chaika ).…”

Comparative morphology of sensilla on antenna, maxillary palp and labial palp of larvae of Eucryptorrhynchus scrobiculatus (Olivier) and E. brandti (Harold) (Coleoptera: Curculionidae)

“…Sensilla with similar morphometrics are observed in many insects, including Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae), Nitidula carnaria Schaller (Coleoptera: Nitidulidae), Languria mozaradi Latreille (Coleoptera: Languriidae), Chrysolina aeruginosa Fald (Coleoptera: Chrysomelidae), Hypera postica (gyllenhal) (Coleoptera: Curculionidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae;Bland 1983;Baker and Ellsbury 1989;Bloom et al 1982;Farazmand and Chaika 2008;Giglio et al 2013;Ortloff et al 2014;Xu et al 2017). Sensilla with similar morphometrics are observed in many insects, including Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae), Nitidula carnaria Schaller (Coleoptera: Nitidulidae), Languria mozaradi Latreille (Coleoptera: Languriidae), Chrysolina aeruginosa Fald (Coleoptera: Chrysomelidae), Hypera postica (gyllenhal) (Coleoptera: Curculionidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae;Bland 1983;Baker and Ellsbury 1989;Bloom et al 1982;Farazmand and Chaika 2008;Giglio et al 2013;Ortloff et al 2014;Xu et al 2017).…”