Synthesis of a material with high juvenile hormone activity

Chemosterilants for Control of Insects and Insect Vectors of Disease

Both historically and at present, vector control is the most generally effective means of controlling malaria transmission. Insecticides are the predominant method of vector control, but the sterile insect technique (SIT) is a complementary strategy with a successful track record in both agricultural and public health sectors. Strategies of genetic and radiation-induced sterilization of Anopheles have to date been limited by logistical and/or regulatory hurdles. A safe and effective mosquito chemosterilant would therefore be of major utility to future deployment of SIT for malaria control. Here we review the prior and current use of chemosterilants in SIT, and assess the potential for future research. Recent genomic and proteomic studies reveal opportunities for specific targeting of seminal fluid proteins, and the capacity to interfere with sperm motility and storage in the female.

Juvenile and moulting hormones from nematodes

Juvenile hormone and its analogues inhibited growth of Panagrellus redivivus and of the free-living stages of Haemonchus contortus. Substances extracted from nematodes had similar actions and also showed the activity of juvenile hormone in insects. Partly purified material from 1 g of freezedried juveniles of H. contortus contained about 200 Tenebrio units.

Juvenile hormone in adult eusocial Hymenoptera: gonadotropin and behavioral pacemaker

Studies on the role of juvenile hormone (JH) in adult social Hymenoptera have focused on the regulation of two fundamental aspects of colony organization: reproductive division of labor between queens and workers and age-related division of labor among workers. JH acts as a gonadotropin in the primitively eusocial wasp and bumble bee species studied, and may also play this role in the advanced eusocial fire ants. However, there is no evidence that JH acts as a traditional gonadotropin in the advanced eusocial honey bee or in the few other ant species that have recently begun to be studied. The role of JH in age-related division of labor has been most thoroughly examined in honey bees. Results of these studies demonstrate that JH acts as a "behavioral pacemaker," influencing how fast a worker grows up and makes the transition from nest activities to foraging. Hypotheses concerning the evolutionary relationship between the two functions of JH in adult eusocial Hymenoptera are discussed.

Development of morphogenetic agents in insect control

Chemicals which interfere with the growth and development of insects (morphogenetic agents) have been receiving major attention as potential means of selective insect control. Major advances in this field resulted from the identification of Juvenile Hormones -1, -2, and -3, and the discovery that various terpenoid and sesquiterpenoid derivatives were more potent morphogenetic agents than the three known Juvenile Hormones. Several highly active compounds have emerged from these research programs. Their field performance, problems, and prospects in selective insect control are considered here.

Juvenile hormone induction of esterases: a mechanism for the regulation of juvenile hormone titer

Within a few hours after injection of juvenile hormone into Hyalophora gloveri pupae, several fast-migrating carboxylesterases (EC 3.1.1.1) that are sensitive to diisopropylfluorophosphate appear in the hemolymph. Treatment of the pupae with puromycin or actinomycin D prevents the appearance of these hemolymph enzymes, suggesting de novo synthesis of the carboxylesterases. Of the several other compounds investigated, only a potent mimic of the juvenile hormone is able to induce these enzymes. When the induced enzymes are incubated in vitro with (14)C-labeled juvenile hormone, the hormone is rapidly and efficiently degraded. It is suggested that these induced carboxylesterases play an important role in the regulation of juvenile hormone titer.

Insect hormones and their derivatives as insecticides

The hormonal control of moulting, reproduction, and diapause in insects has little or no relationship to any similar phenomena in other animals, and the hormones involved in these processes are unlike any known hormones of vertebrates.The availability of pure chemicals with high biological activity has permitted an astonishing increase in research on insect hormones. At present, understanding of insect endocrinology is far too incomplete to justify much speculation about the possibility of using insect hormones as insecticides. However, the preliminary studies discussed in this paper give reason for hope, and the results justify further effort.

Control of gene activities in the polytene chromosomes of Chironomus tentans by ecdysone and juvenile hormone

The injection of ecdysone (molting hormone) into chironomid larvae is known to result in the stimulation of specific gene activities (increased RNA synthesis). The morphological manifestation of this gene activation is the formation of a puff. Cytological and autoradiographic analysis of several regions of the salivary gland chromosomes of Chironomus tentans revealed that ecdysone also stimulates Balbiani ring 1. In contradistinction to the puffs, the Balbiani rings are tissue specific and account for a significant percentage of the cell's non-nucleolar RNA.The application of juvenile hormone results in a decreased activity of Balbiani ring 1, suggesting that the two hormones may act antagonistically. In addition, juvenile hormone induces a puff at chromosome region I-19-A and this puff becomes less active after a short-term treatment with ecdysone. These data demonstrate an effect of juvenile hormone on puffing and are the first to demonstrate activation of a Balbiani ring by ecdysone.

Juvenile hormone: effects on a higher dipteran

Injection of dl-juvenile hormone or C(17) methyl ester into Sarcophaga bullata larvae prevents puparium formation or arrests development at about the 3rd day of pupal-adult development. Topical application to the abdomens of young pupae results in the secretion of a second pupal cuticle. This is the first reported morphogenetic effect of juvenile hormone on a fly.

Lethal effects of synthetic juvenile hormone on the human body louse

Images

Lethal effects of synthetic juvenile hormone on larvae of the yellow fever mosquito, Aedes aegypti

Emergence of adult mosquitoes is blocked after the addition of 1 part of crude synthetic juvenile hormone to 100,000 parts water. Development is arrested at stages ranging from pupae to fully formed pharate adults incapable of escaping from the pupal exuvium. Fourth-stage larvae just prior to metamorphosis are most sensitive: 40 percent were killed after being exposed for 1 dayto 1 part juvenile hormone in 2 million parts water. The active material also inhibits the hatching of mosquito eggs.