Effect of precocene II on circadian rhythms of feeding and mating behavior in the milkweed bug,Oncopeltus fasciatus

Summary Oncopeltus fasciatus adults were treated with the antiallatotropin, precocene II and the circadian rhythms of feeding and mating behavior were monitored at 2-h intervals from lights on to lights off under 2 photoperiod regimes. Females ovariectomized as 5th instars were monitored for feeding and mating behavior at 2–3-h intervals from lights on to lights off as well. Neither precocene treatment nor ovariectomy was found to affect the mating or feeding behavioral rhythms under any photoperiod regime.Acknowledgment. This work was supported by a National Science Foundation Grant number PCM76-10560 to M.A.R.     

Morphogenetic effect of precocene I and II onSchistocerca gregaria (Forsk)

Summary 4th instar nymphs ofSchistocerca gregaria exposed to precocene I and II by topical application metamorphosed precociously. The ED₅₀ of both compounds were evaluated and, unexpectedly, precocene I was found to be more active than precocene II. All adultiforms were identical and in an advanced form.Acknowledgments. This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Ministère de l'Education du Québec. We are grateful to Gaston Grégoire for rearing the insects.     

Precocene-induced collapse and resorption of corpora allata in nymphs ofLocusta migratoria

Summary Precocene II causes an irreversible regression of corpora allata in young 4th instar nymphs of the migratory locust. Within 2 h after application, the cells collapse. Cell fragments are subsequently phagocytosed by haemocytes.Acknowledgment. Thanks are due to Dr G. B. Staal of Zoecon Corporation for the gift of precocene II, and to the Department of Virology for the use of the electron microscope facilities.     

Precocene treatment of the female tsetse flyGlossina morsitans morsitans sterilises her female offspring

Summary When adult femaleGlossina morsitans morsitans were treated with either precocene I or precocene II, females of the F₁ generation, emerging from pupae of the 2nd, 3rd and 4th reproductive cycles failed to develop oocytes.Acknowledgments. The authors wish to thank Dr G. C. Unnithan for helpful discussions.     

Effects of precocene II and juvenile hormone III on the activity of neurosecretory A-cells inOncopeltus fasciatus

Summary Application of precocene II, topically or by contact method, appears to inhibit the synthetic activity of neurosecretory A-cells of the pars intercerebralis ofOncopeltus fasciatus. Treatment of precocene-treated insects with JH III apparently stimulates the secretory activity of these cells.Supported by National Research Council of Canada grant No. A4669.We thank Dr G. B. Staal, Zoecon Corporation, Palo Alto, California, for the gift of precocene II.     

RH-5849, a nonsteroidal ecdysone agonist,does not mimic makisterone-A inDysdercus koenigii

The response of final instar nymphs ofDysdercus koenigii to topical application of the non-steroidal ecdysone agonist, RH-5849, was dose dependent. The candidate compound produced mortality even at moderate doses, but precocious adult development was not observed. Similar results were obtained after oral administration or injection. Conversely, injections of makisterone-A (the principal moulting hormone ofDysdercus) into 5th instar nymphs resulted in precocious adult development within 4 days. We conclude that RH-5849 does not mimic makisterone-A, as is the case with ecdysone, and that toxicity is mediated instead through non-endocrine targets in this insect species.     

Antifeedant activity of precocenes and analogs onRhodnius prolixus

Summary Precocene and analogs added to the meal of 4th instar larvae ofRhodnius prolixus were tested as antifeedants. While precocene II had a strong antifeedant effect (ED₅₀=48 g/ml), the other compounds showed no drastic inhibition of feeding (ED₅₀>140 g/ml). ATP, a phagostimulant, did not reverse the antifeedant action of precocene II. The mechanism of feeding inhibition is discussed.Acknowledgments. This research was supported by funds from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, and National Science Foundation grants PCM-76-09647 and PCM-79-03245.     

Effects of an insect growth regulator,ZR-2646 on egg fertility in the fleshfly,Sarcophaga bullata

Summary Topical application of an insect growth regulator, ZR-2646 on adult females ofSarcophaga bullata affects the viability of the eggs. The compound is most effective if applied at the time of ovulation.The work was supported by the National Research Council of Canada.I am grateful to Dr G.B. Staal, Zoecon Corporation, Palo Alto, California, for the gift of ZR-2646.     

Effets de l'intoxication par le lindane sur les corpora allata deLocusta migratoria (Orthoptère)

Summary The corpora allata of adult and 5th instar nymphs of the migratory locust exhibit several ultrastructural alterations after lindane intoxication. The type of cell degeneration observed here is very similar to ultrastructural changes obtained after the administration of precocene.     

Insect anti-juvenile hormone and juvenile hormone activity from plants in the genusNama

Summary The insect anti-juvenile hormones precocene I and II (7-methoxy-2,2-dimethyl-2H-1-benzopyran and 6,7-dimethoxy-2,2-dimethyl-2H-1-benzopyran) were identified in three of nineNama (Hydrophyllaceae) species. Precocene I occurred inN. lobbii while precocene II occurred inN. hispidum, N. lobbii andN. sandwicense. N. hispidum contained the highest concentration (ca 0.5% dry weight) of precocene II, which was found in the leaves, stems, seed capsules, corolla, glandular trichomes, and seeds. In addition to the anti-juvenile hormone, insect juvenile hormone activity was detected in the organosoluble extracts ofN. rothrockii andN. sandwicense. N. sandwicense is the first plant discovered to contain compounds with both anti- and juvenile hormone activity.     

In vitro inactivation of corpora allata of the bugOncopeltus fasciatus by precocene II

Summary Corpora allata fromOncopeltus fasciatus incubated in vitro in medium containing 10^–5.35 M (1 g/ml) of precocene II lose their ability to secrete juvenile hormone when reimplanted into last instar larvae.Acknowledgments. We thank Mr K. Dorn, Mrs L. Dolezal, Mrs V. Nötzli-Graf, Mr K.H. Trautmann and Mr A. Schuler for technical help, Dr W. Vogel and Dr A. Dübendorfer for valuable discussions.     

Effect of precocene II on acid phosphatase activity in the large milkweed bug,Oncopeltus fasciatus (Hemiptera: Lygaeidae)

Summary When precocene II was applied to the fourth instar milkweed bug, there was a significant decrease in acid phosphatase activity in the hemolymph at the 40%, 50%, 60%, and 70% time periods in the stadium.     

Precocene inhibition of vitellogenesis inDrosophila melanogaster

Summary A single topical application of precocene I or precocene II inhibits the normal process of vitellogenesis inDrosophila melanogaster. This effect is partly prevented by treatment with JH-11 or spontaneously reversible with time.This work was supported in part by NIH grants AI 15662 and GM 22711.     

Oenocyte and prothoracic gland activity inManduca sexta under varying photoperiod and light conditions

Summary Manduca sexta larvae were subjected to diapause-inducing and diapause-preventing photoperiods, using two types of fluorescents (Indorsun and Blacklight-blue). The oenocytes, prothoracic glands (PTG) and ecdysone levels were examined in 3-day-old 5th instar larvae, 2-day-old and 10-day-old pupae. Our results indicate that oenocytes and PTG cells tend to be more active under long photoperiods while oenocytes only are active under short photoperiods in pupae in diapause. UV light has a definite effect on oenocytes while PTG cells seem to be unaffected. Ecdysone and ecdysterone levels vary with PTG and oenocyte activity at the pupal stage. The significance of these findings is discussed.This work was supported by a research associateship to L.M. by the People's Republic of China and a grant from NSERC to B.J.R.P.     

Sterilization of solanaceous hadda,Epilachna vigintioctopunctata F. by irradiating pupae using gamma radiation

Summary Sterility in males and females was observed in the resulting adults when 3–4-day-old pupae of solanaceous hadda,Epilachna vigintioctopunctata F. were exposed to gamma radiation doses of 2000 rad and 2500 rad. However, at 2500 rad longevity of treated insects was adversely affected.Acknowledgment. Financial help to one of us (J.K.G.) by C.S.I.R. in the form of J.R.F. is gratefully acknowledged. Authors are thankful to Prof. P.N. Srivastava and Dr A.R. Rao, School of Life Sciences, J.N.U. Delhi for providing radiation facility.     

Ecdysterone-induced mortality and inhibition of feeding in diapausingRhodnius prolixus stal

Summary Administration of ecdysterone was fatal to diapausingRhodnius prolixus; the male adults and 19-week-old male fifth instar larvae were more susceptible than the 3-week-old larvae. The hormone also inhibited the feeding activity of the bugs.     

Activity of precocene analogs onLocusta migratoria migratorioides (R. and F.)

Summary Several analogs of precocene have been synthesized and evaluated as potential inhibitors of juvenile hormone onLocusta migratoria. Only 5,7-dimethoxy-2,2-dimethylchromene was active; its ED₅₀ and LD₅₀ were measured and compared to those of precocene I and II.Acknowledgments. This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Ministère de l'Education du Québec. We are grateful to Gaston Grégoire for rearing the insects.     

In vivo inactivation of denervated corpora allata by precocene II in the bug,Oncopeltus fasciatus

Summary Transection of the nervous connections between the brain and the corpus allatum (CA) inOncopeltus fasciatus does not alter the susceptibility of the CA to precocene II in vivo.The authors wish to thank Patricia Ferugia for rearing the insects; Dr D. Soderlund, Department of Entomology, New York State Agricultural Experiment Station for helpful discussions; and Dr A.O. Lea, Department of Entomology, University of Georgia for technical advice. To whom reprint requests should be addressed     

Biological activity of enantiomerically pure forms of insect juvenile hormone I and III inBombyx mori

Summary Biological activity of enantiomerically pure juvenile hormones was assayed by topical application on allatectomizedBombyx fourth instar larvae. JHs tested were (10R)-JH I [methyl (2E,6E,10R,11S)-10,11-epoxy-3,11-dimethyl-7-ethyl-2,6-tridecadienoate], (10S)-JH I [methyl (2E, 6E, 10S, 11R)-10,11-epoxy-3,11-dimethyl-7-ethyl-2,6-tridecadienoate], (10R)-JH III [methyl (2E,6E,10R)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate] and (10S)-JH III [methyl (2E,6E,10S)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate]. Among these compounds, natural (10R)-JH I was most active and the dose needed to induce 50% larval molting was 0.04 g/larva; it was approximately 12,000 times more active than unnatural (10S)-JH I. Though natural (10R)-JH III showed slight biological activity, it was only one three-thousandth of that of (10R)-JH I. Unnatural (10S)-JH III exhibited no biological activity at the levels assayed.     

Arylpyridyl-thiosemicarbazones: A new class of anti-juvenile hormones active against Lepidoptera

Summary A new class of anti-juvenile hormone agents is described. Active anti-juvenile hormone compounds were either diazine thiosemicarbazones or aryl substituted pyridyl thiosemicarbazones, synthesized from substituted benzaldehydes. While many analogs in these classes showed feeding and growth inhibition in a variety of insects, a select group caused formation of precocious pupal characteristics inAgrotis ipsilon (black cutworm) andHeliothis virescens (tobacco budworm) and black cuticle and precocious pupae inManduca sexta (tobacco hornworm). They were active only by diet incorporation. The symptoms of precocious development could be reversed by co-administration of a juvenoid. One of the active compounds was shown to inhibit juvenile hormone biosynthesis in vitro by corpora allata of the cockroachDiploptera punctata. However, none of the compounds were active inhibitors of purified chicken liver prenyl transferase.