Sense Organs on the Antennal Flagellum of Leptoglossus zonatus (Heteroptera: Coreidae)

Abstract

For the first time, antennal sensorial organs of Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae) are described through scanning electron microscopy. The antennae are formed by a scape, pedicel, and a flagellum that is composed of two flagellomeres and is the main bearer of sensorial organs. Five types of sensory structures were identified: Trichoid sensilla, basiconic sensilla, coeloconic sensilla, campaniform sensilla, and placoid sensilla. Trichoid sensilla were divided into five subtypes. The large striated trichoid sensilla have almost straight longitudinally striated cuticles and were present throughout the antenna. Flattened trichoid sensilla were variable-sized curved hairs distributed from the base ofthe scape to the distal end ofthe first flagellomere. Small striated trichoid sensilla were found mainly on the antenna distal flagellomeres. Smooth trichoid sensilla were located at the distal end of the scape and along the entire length of the pedicel, and are the least abundant type on the antenna. Small smooth trichoid sensilla were found precisely on the joints between the pedicel and scape. Based on size and shape, the basiconic sensilla were also divided into five subtypes (Bsl, Bs2, Bs3, Bs4, and Bs5). These all are rod-shaped. Coeloconic sensilla were found exclusively on the second flagellomere ofthe flagellum. Just one campaniform sensilla on each antenna was located on the second flagellomere ofthe flagellum. Finally, a group of 10 oval placoid organs were found at the scape base, in proximity to the joint connecting the antenna to the insect's head.

Morphological study of the antennal sensilla in Gerromorpha (Insecta: Hemiptera: Heteroptera)

“…Their position, shape and structure evidently suggest a mechanosensitive function in the studied taxa. The same shape and size of sensilla campaniformia were described in some taxa of heteropterans such as Reduviidae: Triatominae (Catalá 1997 ), Coreidae (Gonzaga-Segura et al 2013 ), in four species of pentatomids (Ahmad et al 2016 ) and currently on the antenna of gerromorphan species. It seems that these sensilla are common in most taxa of Heteroptera.…”

“…However, in Hydrometridae, sensilla trichoidea can also respond to touch. Similarly, the shape and function of the antennal sensilla chaetica in some heteropterans was described by Catalá ( 1997 ), Chinta et al ( 1997 ), da Rosa et al ( 1999 ), Silva et al ( 2010 ), Rani and Madhavendra ( 1995 , 2005 ) and Gonzaga-Segura et al ( 2013 ), who indicated that they have a mechanosensitive role, which enables true bugs to determine the position of their antenna with respect to their surroundings. Similarly, Keil ( 1997 ) mentioned that sensilla chaetica may allow detection and transmission of diverse mechanical stimuli.…”

“…So in the discussion below, a set of the antennal sensilla in semiaquatic and several terrestrial bugs have been compared, e.g. Pentatomomorpha, Scutelleridae (Romani and Rossi 2009 ), Pentatomidae (Silva et al 2010 ; Zhang et al 2014 ; Ahmad et al 2016 ) and Coreidae (Gonzaga-Segura et al 2013 ), Cimicomorpha: Miridae (Chinta 1997 ) and Reduviidae (Catalá 1997 ).…”

“…We estimated that, in gerromorphan species, two subtypes (ST1 and ST3) of sensilla are numerous and air sensitive, because they are long, probably flexible and can easily be subjected to the vibration of air waves. According to Gonzaga-Segura et al ( 2013 ) some types of antennal sensilla in Coreidae ( Leptoglossus zonatus ) also function in this way. Presently we can state, that large striated sensilla trichoidea in L. zonatus are similar to the ST1 in gerromorphan species and small, smooth sensilla trichoidea in L. zonatus are also similar to ST3 in gerromorphan species.…”

Fine structure and distribution of antennal sensilla of stink bug <i>Arma chinensis</i> (Heteroptera: Pentatomidae)

“…Sensilla coeloconica (SCO) were found only on the second segment of the flagellum of A. chinensis. Sensilla with similar morphological features were found on the flagellum of N. viridula, C. purpurea (West), E. heros, P. guildinii and L. zonatus (Brézot et al 1997, Rani & Madhavendra 2005, Silva et al 2010, Gonzaga-Segura et al 2013 and Reduviidae (Catalá 1997). In social insects, such as ants and wasps, whose behavior is guided by variations in temperature, sensilla coeloconica are chemoreceptors that respond to air temperature changes (Ruchty et al 2009).…”