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In indoor laboratory-cage and outdoor field-cage assays, we evaluated the attraction of released, protein-fed, mature Mediterranean fruit fly females to six volatile compounds emitted by attractive crushed ripe coffee fruit: 3-methyl-1-butanal, decanal, 3-methyl-1-butanol, 2-(Z)-pentenol, 2-(E)-hexenol, and 2-heptanone. Previous tests in a wind tunnel indicated that each of these six compounds was more attractive than clean air to females. In laboratory cage assays, none of the compounds elicited a response significantly greater than that to water. In field-cage assays, 2 or 4 μl of 2-heptanone in 5 ml of water (but none of the other compounds at 2 or 4 μl in 5 ml of water) consistently attracted protein-fed medflies at significant levels that averaged about five times greater than attraction to water alone, although about 40% less than attraction to odor of coffee fruit extract. All types of mature protein-fed females tested (laboratory-cultured virgin, laboratory-cultured mated, wild mated) in field-cage assays responded similarly to 2-heptanone, whereas same-age (9- to 11-day-old) protein-deprived females did not respond significantly to 2-heptanone. Response of protein-fed females to 2-heptanone increased progressively with increasing dose (1, 2, 4, or 8 μl in 5 ml of water). Addition of 2 μl of 2-heptanone or 2 μl of any of the other compounds tested to 5 ml of water extract of coffee fruit did not enhance attractiveness of the extract. Relative to response to water, protein-fed females consistently exhibited a significant positive response to odor of coffee fruit extract but no significant response to odor of Nulure (a proteinaceous food attractant). Together, our findings suggest that mature protein-fed females were responding to 2-heptanone as though it were an oviposition-site stimulus rather than a feeding-site stimulus.

A series of one- and two-dimensional NMR experiments were used to confirm structures of the four racemic trans isomers of ceralure, ethyl 4-(or 5)-iodo-trans-2-methylcyclohexane-1-carboxylate, a synthetic attractant for the male Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Proton and carbon assignments were made on the basis NMR data obtained from 2D chemical shift correlation maps, attached proton tests, and 2D- 1 H homonuclear correlation spectroscopy. Assignments of configuration and conformation, based on NMR, for the four trans isomers of ceralure (A, B 1 , B 2 , and C) were consistent with assignments previously derived from a comparison of the gas chromatographic elution behavior of the trans isomers of ceralure and the trans isomer of trimedlure, 1,1-dimethylethyl 4-(or 5)-chloro-trans-2-methylcyclohexane-1-carboxylate

A capillary GC method has been developed to analyze laboratory or commercial samples of the medfly attractant ceralure [ethyl 4- (and 5-)iodo-trans-2-methylcyclohexane-1-carboxylate]. The method utilizes a specially prepared fused-silica column with a bonded phenyl-methyl polysiloxane liquid phase. Baseline separation was achieved for three of the four trans-ceralure isomers. Difficulties encountered with other columns investigated are also discussed.

The physiological basis of phagodeterrence was studied electrophy-siologically and behaviourally in the phytophagous caterpillars Manduca sexta and Manduca quinquemaculata. The model unacceptable non-host plant was the canna lily, Canna generalis. A strongly deterrent extract was obtained from fresh leaves of canna by extraction with hot ethanol or ethyl acetate in a blender. Behavioural rejection of these extracts was similar to that of fresh leaves, although less intense. In contrast, blender extracts using other solvents, as well as leaf surface rinses, were phagostimulant or neutral. Chromatographic fractionation of the deterrent ethanolic extract showed the active principles to be moderately polar and separable into two fractions. Previous ablation experiments had shown that the medial maxillary styloconica and epipharyngeal sensilla are the two most important chemosensory organs in mediating behavioural rejection of canna leaves; if only one of these organs is spared, the animal completely rejects canna. We investigated the neural responses of the medial styloconica and their contribution to the sensory coding responsible for this phagodeterrence. The active fractions of the deterrent ethanolic extract elicited a vigorous response from one chemosensory neurone in the medial styloconica. This neurone is distinguishable from others in the medial styloconica by its unique temporal response parameters and the characteristic shape changes of its action potentials. The response frequency of this neurone correlates with the degree of phagodeterrence in a dose-dependent manner. Threshold deterrence occurs at a concentration of extract (1%) that elicits firing in this neurone at a rate of c. 50 spikes/s peak instantaneous frequency and 30 total spikes in the first Is. We conclude that this is a ’deterrent neurone’ in the sense that vigorous response from this neurone is a sufficient sensory code for behavioural rejection of canna. Thus input from a single sensory neurone is capable of blocking feeding, since only one (unilateral) medial styloconicum is needed to mediate this rejection.

CIC-4 (1,1,4,5,6,7,8,8a-octahydro-3H-2-benzopyran-3-one) is a fused bicyclic lactone which acts as a non-contact insect repellent for Aedes aegypti at 1% concentration in 95% aqueous ethanol when applied topically to rhesus monkeys. Chromatographic and spectroscopic analyses of a synthetic sample indicated the presence of cis-and trans-fused isomers. To supply each isomer for the assessment of mosquito repellent efficacy on humans, we developed a semi-preparative high-performance liquid chromatographic separation technique for the isomer separation. A column of 5-μm silica was used for isolating milligram quantities of each isomer. By this method, each isomer was obtained in > 95% gas-liquid chromatographic (GLC)-purity for biological evaluation. Supporting GLC and electron impact and chemical ionization gas chromatography-mass spectrometric data are also presented for each isomer. Biological evaluation on the human arm using Anopheles quadrimaculatus, Aedes aegypti, and Anopheles albimanus as the test species was effective in determining relative repellency to the standard N,N-diethyl-3-methyl-benzamide

Azadirachtin (1.0 μg/ml) if fed to last-instar larvae of Rhodnius prolixus through a blood meal, affects the immune reactivity as shown by (i) a significant reduction in numbers of haemocytes and nodule formation following challenge with Enterobacter cloacae B12 (ii) a reduction in ability to produce antibacterial and lysozyme activities in the haemolymph when inoculated with bacteria, (iii) a decreased ability of azadirachtin-treated insects to destroy the primary infection caused by inoculation of E. cloacae cells. However, the present experiments, unlike other immune reactions, fail to demonstrate any interference of azadirachtin with the prophenoloxidase-activating system since the melanin production was not reduced when this system was stimulated by trypsin or by the presence of bacteria in the haemolymph. It is suggested that the immune response is deficient in the azadirachtin-treated insects. The significance of these results is discussed in relation to the general mode of azadirachtin action in insects.

High-performance liquid chromatography has made possible the separation of furanosesquiterpenoids in Commiphora myrrh oil. Combined application of NMR, UV, and MS techniques have revealed that oil from C. myrrh gum resins contains isofuranogermacrene (1), lindestrene (2), furanoeudesma-1,3-diene (3), and furanodiene (4).

6-d-Glucopyranosyl esters of palmitic, oleic, linoleic and linolenic acids were identified in Brassica napus (rape) pollen. These esters are inactive as plant growth promoters in the bean second-internode bioassay.

Extracts of Brassica napus L. (rape) pollen (family, Cruciferae) have been reported to produce a novel growth-promoting effect when applied to young pinto bean plants1,2. Fractions that are active in the bean second-internode assay3 give rise to both increased cell elongation and cell division4. The validity of these early reports has been questioned because biological activity was not correlated with any one pure compound5. Subsequently, we showed that isolation of the growth promoter was complicated by the presence of chromatographically similar, inactive components that were identified as 6-D-glucopyranosyl esters of long-chain fatty acids6. We now report the isolation, structure determination and biological activity of this new plant growth promoter, named (22R, 23R, 24S)-2α-3α,22,23-tetrahydroxy-24-methyl-6,7-s-5α-cholestano-6,7-lactone or brassinolide (Fig. 1).