Comparison of structurally analogous allatotoxins on the molting and morphogenesis of Rhodnius prolixus, and the reversal of ecdysial stasis by ecdysone

Abstract

The allatotoxic effect of 3-ethoxy4methoxy-6iso-pentenylphenol o n nymphal molting and metamorphosis of Rhodnius prolixus was examined. Continuous contact treatment with IPP induced the formation of precocious adults and retarded molting or initiated a permanent ecdysial stasis. Insects treated with 7-ethoxy-6-methoxy-2,2-dimethylchromene were similarly affected. Ecdysone given orally counteracted the ecdysial stasis and also reduced the duration of the molting delay caused by IPP.Key words: Rhodnius prolixus, precocious metamorphosis, allatotoxin, antijuvenile hormone activity, ecdysial stasis, precocene, ecdysone INTRODUCTIONSince the discovery of the antijuvenile hormonal compounds precocene I and I1 [1,2] a significant body of literature has accumulated detailing the action of these compounds on insects [3-51. In general, these investigations show that the precocenes inhibit development of the corpus allatum [1,2,6-81 through an induced atrophy of its parenchymal cells [9-111. The degeneration of the gland and its subsequent invasion by connective tissue terminates JH* production in vivo [l-31 and in vitro [12-l5]. Morphogenetic, 'Abbreviations: Ethoxy precocene I I = 7-ethoxy-6-methoxy-2,2-dimethyl chromene = EPII; 3-ethoxy4methoxy-6-iso-pentenylphenol = IPP; juvenile hormone = JH; prothoracicotropic hormone = PTrH.Acknowledgments:

Inhibition of ecdysteroid production in nymphs of Rhodnius prolixus treated with ethoxyprecocene II

“…The molting stasis induced by EPII could be prevented by feeding the nymphs with 20-hydroxyecdysone at 4 pglml of blood. In the group receiving EPII (20 pglml of blood) and 20-hydroxyecdysone together, 85% molted within 14-19 days, confirming our earlier data in which the ecdysial stasis induced by precocenes was reversed with ecdysone (17,18,23). These results strongly suggest that the observed delay, or complete arrest, of molting in Rhodnius following EPII treatment may result from a direct or indirect action of this antijuvenile hormone on PG production of ecdysone.…”

“…These studies clearly show that, in addition to inducing precocious metamorphosis, EPII prolongs or entirely inhibits molting in R. prolixus nymphs. We show that both effects induced by EPII, as we have demonstrated for other precocenes (17,18,23), can be reversed by therapy with 20-hydroxyecdysone. Further, we demonstrate that EPII can limit or abolish ecdysteroid synthesis by the PG in vitro.…”

“…We show that both effects induced by EPII, as we have demonstrated for other precocenes (17,18,23), can be reversed by therapy with 20-hydroxyecdysone. Further, we demonstrate that EPII can limit or abolish ecdysteroid synthesis by the PG in vitro.…”

Age‐dependent responses of last instar larvae of Spodoptera mauritia to precocene II

“…Box 673 635, Kerala, India. Pedersen, 1978;Tarrant & Cupp, 1978;Chang et al, 1979;Masner et al, 1979;Sieber & Benz, 1980;Unnithan et al, 1980;Wilson et al, 1983;Sam Mathai & Nair, 1983, 1984aBitsch & Bitsch, 1984;Garcia et al, 1984). The corpora allata (CA) of insects treated with precocenes undergo necrosis and degeneration preventing their ability to produce JH (Unnithan et al, 1977;Pener et al, 1978;Schooneveld, 1979;Feyereisen et al, 1981).…”

Biomorphological Alterations Induced by an Anti-juvenile Hormonal Compound, 2-(2-EthoxyEthoxy)Ethyl Furfuryl Ether, on Three Species of Triatominae Larvae (Hemiptera, Reduviidae)

“…The effects of precocenes were investigated in different triatomine species. For example, Azambuja et al (1981), Garcia et al (1984Garcia et al ( , 1988 and Jurberg et al (1982Jurberg et al ( , 1984Jurberg et al ( , 1986 described the actions of precocene in Rhodnius prolixus, Panstrongylus megistus and Triatoma infestans.…”