Two simple chromenes with anti-JH activity have been isolated and identified from the bedding plant Ageratum houstoianum. By contact and fumigation these compounds induce precocious metamorphosis and sterilization in several hemipteran species of insects. Certain holometabolous species are sterilized, forced into diapause, or both. Each of these biological actions is equivalent to removal of the corpora allata, which produce the JH's, and is reversible by treatment with exogenous JH. Thus, the action of these compounds is to stop the production or depress the titer of the JH's. To our knowledge, this is the first discovery of anti-JH, and we hope it will guide the way to the emergence of a fourth generation of safe and insect-specific pesticides.

https://science.sciencemag.org/content/sci/193/4253/542.full.pdf

Discovery of insect anti-juvenile hormones in plants.?2U

The juvenile hormones: historical facts and speculations on future research directions.

Publisher Summary This chapter discusses the juvenile hormones (JH). The JH, a family of acyclic sesquiterpenoids, are essential to insect development and reproduction. This chapter examines the new compounds that have been added to the family. Recent structural elucidation of the hemolymph transport and catabolic proteins is examined. Molecular biology surrounding the long-sought JH receptor and potential candidates are discussed. The juvenile hormones, a family of acyclic sesquiterpenoids, are essential to insect development and reproduction. This family of hormones has been extensively studied because of its central role in regulating development and value as an insect pest control agent. Recent advances have been made in the areas of chemistry, biosynthesis, transport, catabolism, and biological roles the hormones play in the immature insect. Two common features characterize the naturally occurring JHs: their site of synthesis, the corpora allata (CA), and their farnesoid structure.

The Juvenile Hormones

Publisher Summary This chapter discusses the structure and regulation of the corpus allatum. The corpora allata (CA) are endocrine glands in the posterior regions of the head, or in rare instances in the thorax, which are closely associated with the stomatogastric nervous system. This chapter focuses on the regulation of the CA. It also describes the embryology, innervations, and the relationships of the structure, particularly the ultrastructure, to its synthetic activity. The characteristic shape of the CA is ovoid to round but they may be elongate as in large larvae and adults of Libellula depressa. The size of the glands is frequently about the diameter of the aorta or smaller; however, there is much variation among species and even within a species, size differs with age, sex, polymorphism, and the activity cycle of the glands. Although only one type of glandular cell occurs in the CA, there are a variety of types of CA with respect to the number of cells per gland and the relative size of the cells. The CA are surrounded by a continuous noncellular basal lamina, roughly 0.1-1 μ m thick. This material occasionally projects between two glandular cells into the interior of the gland, forming trabeculae that may accompany nerves and trachea.

Structure and Regulation of the Corpus Allatum

Publisher Summary One of the fundamental questions concerning the role of lipids in the physiology of the insect concerns the quantity of lipid contained upon, and interior to, the rigid exoskeleton. Lipids are of vital importance to many insects as substrates for embryogenesis, metamorphosis and flight. Although several problems of the function and metabolism of lipid in insects have been unraveled in recent years, this research area remains ripe for invasion by both the entomologist and biochemist. The task of assuring that insects utilize the same metabolic pathways as micro-organisms and vertebrates has not yet been completed. This chapter concentrates on developments within the past ten years but also discusses older literature when applicable to the historical development of the topic. In most cases, sophisticated experiments have been conducted on only a few species of “domesticated” insects and the result cannot be extrapolated to all insects. The multitude of different ecological niches and behavioral characteristics are no doubt reflected in a great number of metabolic variations on perhaps more than one basic theme.

Lipid Metabolism and Function in Insects

Some years ago we reviewed the status of the insect juvenile hormone (JH) and its isolation.1 Since then two noteworthy contributions toward purification of the hormone have appeared.2' In all these purification attempts adult male Cecropia silk moths4 proved to be an invaluable source material. The first nearly pure hormone preparation was isolated in 1965.1 We obtained it from Cecropia oil (second batch) and characterized it by means of a gas-liquid chromatographic (GLC) analysis in conjunction with an ultrasensitive argon ionization systemA The hormonal activity was located exclusively in the two major peaks B and E. Both these substances had a specific activity of the same magnitude as the original preparation. They were retained on neopentyl glycol adipate (NGA) columns at ratios of 1.60 and 1.29 relative to methyl stearate. Only one contamination, peak H, was apparent, which amounted to less than 10 per cent of the total peak area. Thus our 3 X 105-fold enriched preparation was at least 90 per cent pure. A host of subsidiary gas chromatographic peaks (A,D, etc.) were artifacts that resulted from reactions of the active compounds in the analytical system. These substances were produced even though the hormonal preparations had been injected with a Hamilton syringe directly onto the packed glass columns, but they were more plentiful in the fractions that had been previously submitted to a GLC separation and collected after passage through the brass detector cell. Since the same pyrolytic products were formed whether they were derived from compound B or compound E, the two hormonally active compounds had to be closely related structurally. We have now processed a new (third) batch of Cecropia oil by a five-step purification sequence similar to that applied to the second batch. These steps w-ere: (I) molecular distillation at -1 mTorr and 1000C; (II) separation from acidic products formed; (III) leaching with cold aqueous methanol; (IV) SiO2 chromatography; and (V) A1203 chromatography. One modification had been made in step IV in which an improved silica gel system was substituted for the zinc carbonate sy-stem6 previously used. This resulted in eliminating compound H. In the Galleria N-lX test, fractions of the final preparation again exhibited a potrency of some 3 X 105 JH units per milligram (Table 1). Our GLC unit wsas perfected by construction of a metal-free injector and a glass effluent splitter. As a result, the hormone preparation could be processed through the system without contacting any metal. From then on, much simplified chromatograms have been recorded (Fig. 1). The GLC analysis of the biologically most active fractions of the pure preparation revealed that they were composed of only two substances: compounds B and E (Table 1). When the

The two juvenile hormones from the cecropia silk moth.

Purified extract of juvenile hormone from the cecropia silkmoth prevents the transformation of larva to pupa in Galleria. The injected extract acts independently of the insect's own corpora allata....

Larval-Pupal Transformation: Control by Juvenile Hormone

The isolation and identification of the two juvenile hormones from the Cecropia silk moth.

The absolute configuration of the predominant Cecropia hormone, methyl 12,14-dihomojuvenate, has been determined to be methyl (E,E)-(10R,11S)-(+)-10,11-epoxy-7-ethyl-3,11-dimethyl-2, 6-tridecadienoate (I). The less abundant hormone, methyl 12-homojuvenate, can be presumed by analogy to have the corresponding 3,7,11-trimethyldienoate structure (II). The assignment has been established with microamounts of substance by applying Horeau's method to the glycol derivative (III) of the hormone. 

The course of the perchloric acid-catalyzed epoxide ring opening of I was checked by conducting the conversion in 18O-labeled water. It has been ascertained that the configuration at the secondary hydroxyl group of the resulting III remained unchanged. On the other hand, the hydration proceeded with a surprisingly high rate of cis opening.

Absolute Configuration of Cecropia Juvenile Hormone

Methyl cis-10-epoxy-3,7,11-trimethyl-trans,trans-2,6-tridecadienoate has been stereoselectively synthesized in 12 steps starting from methyl trans-γ-bromo-β,β-dimethylacrylate and 1-acetyl-1-methylcyclopropane. The final product proved to be identical with the second, less abundant juvenile hormone (methyl 12-homojuvenate) isolated from the Cecropia silk moth. The biological activities of the compound were evaluated in various insects.

Andre S. Meyer

Papers

The two juvenile hormones from the cecropia silk moth.

Larval-Pupal Transformation: Control by Juvenile Hormone

The isolation and identification of the two juvenile hormones from the Cecropia silk moth.

Absolute Configuration of Cecropia Juvenile Hormone

Total synthesis of the racemic form of the second juvenile hormone (methyl 12-homojuvenate) from the cecropia silk moth