Effects of two juvenile hormone analogs (R‐20458, RO203600) and three juvenile hormones (JH 1, 2, and 3) on the number and distribution of sensilla on the seventh abdominal tergite in the male German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae)

Abstract

Three types of sensilla, s. chaetica B, s. trichoidea, and s. campaniformia were identified on the 7th abdominal tergite of JH-JHA-and acetone (control)-treated adult male Blattella germanica by light and scanning electron microscopy. All contact chemoreceptors (s. chaetica B) and the majority of mechanoreceptors (s. trichoidea) surround the gland openings or cover the tergal modification, which indicates that contact chemoreception and mechanoreception are important in the tergal feeding stage of mating behavior. The numbers of all three types of sensilla were significantly reduced for all five treatments.In many species of cockroaches, the males have photoperiod and reared on purina laboratory chow evolved tergal glands with corresponding modified and water. Thirty 1-3-day-old, 6th (last) instar terga that play a crucial role in sexual behavior. males were treated topically with 0.2 pghnsect In Blattella germanica males, numerous sensilla, of R-20458 (6, 7-epoxy-l-(p-ethylphenoxy)S, 7-diassociated with the 7th tergal modification and methyl-trans-2-octene) (2 pl); 2.5 pghsect R020-involved in tergal feeding, surround the gland 3600 (6, 7-epoxy-3-methyl-7-ethyl-1-(3,4-methyleneopenings. Studies have shown three sensilla types dioxyphenoxy>2-~tene) (5 pl); 2 pghnsect juvenile (Sreng, '76): s. campaniformia and two other types hormone 1 (JH 1) (methyl-lO-ll-epoxy-7-ethyl-3,ll-which are characterized by pointed tips and either dimethyl-2,6-tridecadienoate,cis/trans mixture) (2 longitudinally fluted (20-pm-long) or smooth (5-10-pl), 2 pglinsect juvenile hormone 2 (JH 2) (2 pl), 7.5 pm-long) walls. The internal morphology and func-pglinsect juvenile hormone 3 (JH 3) (6 pl); or 2, 5, tion of the fluted-walled and smooth types have or 6 p1 of acetone, respectively (controls). been described.Ten excised 7th abdominal terga from normal The 7th abdominal tergum possesses the spicu-adult males were prepared for scanning electron lum copulatus, a structure crucial for mating (Ra-microscopy (SEMI (Ramaswamy and Gupta, '81). maswamy et al., '80; Wheeler and Gupta, '87), and The types of sensilla on the normal tergite were the two anterior tergal gland openings. No one has noted. Whole mounts of the terga from acetone reported the numbers and distributions of sensilla control and treated adult males were prepared for on the 7th tergum in male B. germanica or how light microscopy (Ramaswamy and Gupta, '8U, and insect growth regulator affects them. We repoh the the numbers of each sensilla type for each treateffects of R-20458, R0203600, JH 1, JH 2, and JH ment were recorded. Comparisons were made be-

Effects of the juvenile hormone analog pyriproxyfen on German cockroach,Blattella germanica (L.), tergal gland development and production of tergal gland secretion proteins

“…These findings are in agreement with those of Wheeler and Gupta (1987), who reported that treatment with JH caused deformation of the spiculum copulatus, that included various degrees of distortion to the exterior surface and a significant reduction in length. Third, the G1 and G2 cells of treated tergal glands seemed to be arranged in a less orderly fashion within the tissue.…”

“…Treatment with JHA has also been shown to cause a reduction in the number of sensilla associated with the tergal gland openings on tergite seven (Wheeler and Gupta, 1988). The research reported here was designed to examine effects of the JH analog pyriproxyfen on tergal gland secretory tissue development, including the structure of secretory cells and the production of tergal gland secretion proteins.…”

“…Because tergal glands are adult structures that do not begin developing until the last instar (Sreng and Quennedey, 1976), it follows that an absence of JH in the last instar would be necessary for tergal gland secretory cell development to proceed normally. Indeed, treatment of German cockroaches with JH analog during the last instar has been shown to cause deleterious effects on adult sense organs associated with mating (Ramaswamy and Gupta, 1981) and on tergal gland structures including the spiculum copulatus (Wheeler and Gupta, 1987) and tergal gland sensilla (Wheeler and Gupta, 1988). (King and Bennett, 1988;Kawada et al, 1989).…”