Squash leaf glandular trichome volatiles: Identification and influence on behavior of female pickleworm moth [Diaphania nitidalis (Stoll.)] (Lepidoptera: Pyralidae)

Fourteen volatile compounds occurring in leaf trichomes of yellow squash (Cucurbita pepo L. cv. Early Prolific Straightneck) were identified. These compounds accounted for 83.5% of the volatile matrix. Ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. The volatileso-,m-, andp-xylene, toluene, 2-heptanone, (R)-(+)- and (S)-(–)-limonene, and germacrene D were tested for their influence on attraction and oviposition by the pickleworm moth (Diaphania nitidalis Stoll.). No single compound, except germacrene D, was attractive. (R)-(+)-Limonene and 2-heptanone were weakly repellent. Mixtures of the highly volatile fractions were as attractive as volatiles emanating from whole, intact leaves. Oviposition levels on treated artificial sites corresponded with levels of visitation. Oviposition was significantly stimulated by whole-leaf volatiles, and (S)-(–)-limonene caused a slight but significant reduction.Mention of a trade name or proprietary product does not constitute a warranty or guarantee by the U.S. Department of Agriculture, nor does it imply exclusion of other products that may also be suitable.     

Fine structure and formation of the eggshell in scorpionfly Panorpa liui Hua (Mecoptera: Panorpidae)

The morphology and formation of the eggshell in the scorpionfly Panorpa liui Hua were examined with light microscopy and scanning and transmission electron microscopy. During oogenesis of the scorpionfly, the follicle cells multiply by mitotic divisions and diversify into four morphologically distinct subpopulations, three of which are engaged in the eggshell formation and mold various parts of chorion. The eggshell consists of three layers: An inner vitelline membrane, an outer chorion, and a precursor extrachorion. The chorion constitutes a very compact endochorion, a rough fibrillar exochorion, and a polygonal meshwork of elevated ridges. At proximal end of ovarioles the chorion of matured oocyte is covered with a loose membrane, which might be the remnant of follicle cells. The jelly substance, which acts as lubricant to protect the oviducts and ovulated eggs during ovulation, might add to the top of polygonal ridges as the outermost extrachorion after oviposition. The eggshell formation process in Panorpa is tentatively proposed. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc.     

Structure-activity relationship observations oftrans-trimedlure enantiomers

tert-Butyl 4- (and 5-) chloro-trans-2-methylcyclohexane-1-carboxylate (TML), a mixture of four majortrans and four minorcis isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly (medfly),Ceratitis capitata (Wiedemann). The eight isomers (racemic mixtures) were isolated by HPLC, and their relative attractiveness in the field was determined. A quantitative structure-activity relationship (QSAR) was proposed that related a molecular measurement (ų) of the TML structure to male medfly captures. More recently, thetrans-TML enantiomers were synthesized in sufficient quantities for field testing. This paper reports the computer-aided molecular modeling, via Chem-X, of thetrans-TML enantiomers and the staggered and superimposed fitting with the most attractive isomer, (1S,2S,4R)-TML-C, to determine common volumes and surface areas from Van der Waals (VdW) maps. Observations of structure-activity relationships (SAR) are reported for the staggered fittings.     

Cuticular hydrocarbons ofAedes hendersoni cockerell andA. triseriatus (SAY)

Field-caught adult male and femaleAedes hendersoni are difficult to distinguish from the sibling speciesA. triseriatus. We found that mosquitoes from the same sex of the sibling species can not be readily separated either by unique cuticular hydrocarbon components or by differences in percent composition of those components. Multivariate analysis of the cuticular hydrocarbon data does not provide good separation. Cuticular hydrocarbons were identified using gas chromatography electron-impact mass spectrometry and gas chromatography chemical-ionization mass spectrometry. Flame-ionization capillary gas chromatography was used for quantitative analysis of individual mosquitoes. Sixty-four hydrocarbons with chain lengths from C₁₆ to greater than C₄₆ were common to both species. Identified hydrocarbon components weren-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and alkenes.Diptera: Culicidae.     

Lanierone: A new pheromone component fromIps pini (Coleoptera: Scolytidae) in New York

A new pheromone component, lanierone, (2-hydroxy-4,4,6-trimethyl-2,5-cyclohexadien-1-one) was isolated and identified from a Porapak Q collection of volatiles from maleIps pini from New York through GC fractionation, bioassay, and spectrometry. In both the laboratory and the field, synthetic lanierone, in a 1:100 ratio with synthetic ipsdienol, is as attractive as natural pheromone sources. Synthetic ipsdienol alone is not attractive in the laboratory and only weakly attractive in the field. Varying the ratio of lanierone to ipsdienol in the field from 10^–41 to 11 in 10-fold increments resulted in an increased number of beetles trapped at the three lower ratios, but also in an increase in the proportion of males trapped. In the field, all combinations of lanierone to ipsdienol attracted proportionately fewer males than did pheromone-producing male beetles. GC and GC-MS analyses of Porapak Q-trapped volatiles revealed that lanierone is produced in an amount equal to about 0.2% of that of ipsdienol and is produced exclusively by males. The small amount of lanierone produced, together with a GC retention time similar to that of ipsdienol on a nonpolar column, probably confounded its detection in earlier studies.Deceased.     

Synergism between chemical attractants and visual cues influencing oviposition of the mosquito,Culex quinquefasciatus (Diptera: Culicidae)

Physical factors, such as the color of the oviposition substrate, have seldom been compared with chemical cues in their ability to elicit oviposition behavior in mosquitoes. The role of dyed oviposition waters in attracting ovipositingCulex quinquefasciatus was examined in laboratory experiments. Oviposition waters dyed with ink were found to be significantly attractive to ovipositingCx. quinquefasciatus when compared to distilled water controls. Experiments demonstrated that the mosquitoes were responding to the increased optical density of the dyed oviposition water rather than volatile components of the dye. Ink was also considered in combination with chemical oviposition cues. No comparative data exist on the effect of physical and chemical factors presented together on the oviposition behavior ofCx. quinquefasciatus. Waters dyed with ink acted synergistically with a five-component chemical attractant mixture (3-methylindole, indole, 4-methylphenol, 4-ethylphenol, and phenol) in inducing oviposition in a 2×2 factorial experiment.     

Imaging applications of synchrotron X-ray phase-contrast microtomography in biological morphology and biomaterials science. I. General aspects of the technique and its advantages in the analysis of millimetre-sized arthropod structure

Synchrotron‐generated X‐rays provide scientists with a multitude of investigative techniques well suited for the analysis of the composition and structure of all types of materials and specimens. Here, we describe the properties of synchrotron‐generated X‐rays and the advantages that they provide for qualitative morphological research of millimetre‐sized biological organisms and biomaterials. Case studies of the anatomy of insect heads, of whole microarthropods and of the three‐dimensional reconstruction of the cuticular tendons of jumping beetles, all performed at the beamline ID19 of the European Synchrotron Radiation Facility (ESRF), are presented to illustrate the techniques of phase‐contrast tomography available for anatomical and structural investigations. Various sample preparation techniques are described and compared and experimental settings that we have found to be particularly successful are given. On comparing the strengths and weaknesses of the technique with traditional histological thin sectioning, we conclude that synchrotron radiation microtomography has a great potential in biological microanatomy.     

Rhodanese in insects

Forty-four species of insects were assayed for the presence of rhodanese, an enzyme generally considered to be responsible for the detoxification of cyanide. Rhodanese was found to be widely distributed in both adults and larvae and was not restricted to those species which encounter exogenous cyanide through feeding on cyanogenic plants. These results indicate that cyanide detoxification is unlikely to be the primary role for rhodanese in insects.     

Evaluation of organic infusions and synthetic compounds mediating oviposition inAedes albopictus andAedes aegypti (Diptera: Culicidae)

Oviposition responses of gravidAedes albopictus andAe. aegypti were evaluated to natural organic infusions (hay infusion, larval rearing water, and field-collected larval water) as well as compounds isolated from hay infusion (3-methylindole, 4-methylphenol, 4-ethylphenol, indole, and phenol) known to elicit oviposition inCulex mosquitoes. In laboratory bioassays, significant oviposition responses were obtained fromAe. albopictus, but not fromAe. aegypti, to dilutions of hay infusion and field water. Oviposition responses of both species were moderate to the synthetic compounds tested in the laboratory (0.01–100 µg/liter). Only 3-methylindole (0.1 µg/liter) and 4-ethylphenol (1.0 µg/liter) elicited significantly more oviposition byAe. albopictus than did well water. Of the synthetic compounds tested withAe. aegypti, only phenol (1.0 µg/liter) and 4-ethylphenol (0.1 µg/liter) elicited significantly more oviposition than did well water. Significant repellency or oviposition deterrence for both species occurred in response to at least one high concentration of most of the compounds tested. In field cage evaluations, oviposition responses byAe. albopictus were strongest to larval water and field water, moderate to hay infusion and 3-methylindole (100 µg/liter), and low to well water. A mixture of five synthetic compounds mimicking hay infusion was no more effective than 3-methylindole alone. ForAe. aegypti, oviposition responses were greatest to larval water and least to 3-methylindole. In an olfactometer, gravid females of both species oriented more to field water than to well water and onlyAe. albopictus oriented more to larval water or hay infusion than well water. In general, gravidAe. albopictus responded more strongly to oviposition stimuli than didAe. aegypti.     

Identification of an attractant for the caneborerSesamia grisescens walker (Lepidoptera: Noctuidae)

The composition of the sex pheromone ofSesamia grisescens was investigated using gas chromatography, electroantennograms, and field trapping. (Z)-11-Hexadecenyl acetate and (Z)-11-hexadecenol were identified in field tests as the major attractants. Trapping trials identified a 3:2 blend of these compounds as the most effective bait. Gas chromatography indicated the presence of hexadecyl acetate. (Z)-9-hexadecenyl acetate, (Z)-9-hexadecenol, and (E)-11-hexadecenyl acetate in the pheromone gland, but these compounds had no significant effect on trap catches when added to the major components. Traps baited with the major components in a 1:1 ratio caught more male moths than traps baited with virgin females.