Lyle K. Gaston

Clarification of the Chemical Status of the Pink Bollworm Sex Pheromone

Propylure, 10-n-propyl-trans-5,9-tridecadienyl acetate, and deet, N,N,-diethyl-m-tolumide, were previously reported as the sex pheromone and a sex pheromone activator, respectively, of the pink bollworm. Neither chemical in three extracts of female moth abdomen tips could be detected by gas-liquid chromatographic analysis. These compounds, alone or in combination, exhibited little or no biological activity in the laboratory or in the field. Hexalure, cis-7-hexadecenyl acetate, a synthetic attractant for pink bollworm males, could not be detected in female moth abdomen tip extracts. The pink bollworm sex pheromone was identified as a mixture of cis,cis and cis,trans isomers of 7,11-hexadecadienyl acetate.

Composition, quantification, and periodicity of sex pheromone gland volatiles from individualHeliothis virescens females.

Sex pheromone gland volatiles from individualHeliothis virescens (F.) females were collected and analyzed on an SP-2330 capillary gas-liquid chromatography column for identification and quantification of the compounds emitted. Only four of the seven compounds previously reported as pheromone components appeared consistently in the volatile collections: 14:Ald, Z9-14:Ald, 16:Ald, and Z11-16:Ald. The female glands did not emit the same amounts of these compounds throughout a 24-hr period; they emitted maximum quantities between 6 and 11 hr after the onset of scotophase with the remainder of the photoperiod having minimal emission rates. Although the absolute quantities fluctuated, the percent compositions of the compounds remained about the same throughout the 24-hr period.

Composition, quantification, and periodicity of sex pheromone volatiles from individual Heliothis zea females

Abstract The airborne volatiles emitted from individual female Heliothis zea (Boddie) pheromone glands were collected by adsorption onto glass wool, analyzed, and quantified on an SP-2330 capillary GLC column. All of the compounds previously reported from gland washes, 16:Ald, Z7-16:Ald, Z9-16:Ald and Z11-16:Ald, were found in the volatile emissions. The forcibly extruded female H. zea pheromone glands exhibited a periodicity of pheromone release: maximal pheromone emission occurred between 1 and 2 h and the minimal pheromone emission between 5 and 21 h after the onset of scotophase.

Sex pheromones of noctuid moths: factors influencing antennal responsiveness in males of Trichoplusia ni.

Abstract A procedure was developed for recording electroantennograms (EAGs) from pheromone-stimulated antennae of males of Trichoplusia ni . Experimental evidence indicated that the EAG was a true measure of male olfactory response. Antennae recovered from sensory adaptation to the sex pheromone within 30 to 60 sec after exposure. Variations in age, light intensity, and time of day did not affect antennal responsiveness to sex pheromone, although the same variables had an effect on the behavioural responsiveness of intact male moths.

Insect Population Control by the Use of Sex Pheromones to inhibit Orientation between the Sexes

SEVERAL people have speculated on the thesis that if a sufficiently high concentration of an insect sex pheromone could be maintained in the atmosphere, the sexes could not find each other for mating purposes1–3 (for a review, see Jacobson4). Their conclusion was that this could lead to control or possibly eradication of the species. In the only large scale experiment to test this principle, gyplure, an analogue of the gypsy moth sex pheromone, was distributed over an island infested with gypsy moths5. Mating of males with females was not prevented; the failure of this experiment was attributed to the presence of a “masking” substance in the synthetic pheromone6. We have for the first time obtained experimental confirmation that pre-mating communication between the sexes can be disrupted by permeating the atmosphere with an insect pheromone. This general phenomenon was demonstrated using Trichoplusia ni (Hübner), the cabbage looper, as the test organism.

A high-efficiency collection device for quantifying sex pheromone volatilized from female glands and synthetic sources

A high-efficiency collection device for sex pheromones volatized from forcibly extruded female glands is described. Filtered nitrogen gas is the carrier and glass wool the adsorbent. Small quantities of distilled carbon disulfide are used to rinse the glass wool. Recovery efficiency of synthetic compounds was usually 90–100%, and a mean of 2.4 ± 0.65 SD ng/min of (Z)-7-dodecenyl acetate was recovered in emissions from individualTrichoplusia ni (Hubner) glands.

Temporal pattern of sex pheromone release by female Trichoplusia ni

Abstract The release rate of the pheromone component Z-7-dodecenyl acetate was determined for individual female Trichoplusia ni by using small glass tubes filled with Porapak Q to extract pheromone from air in the immediate vicinity of the everted gland. The change in release rate as a function of time was determined by taking sequential 5 min. samples from individual 4-day-old females through each pheromone release period over an entire night. The release rate was found to decline exponentially from a mean of 22 ng per min. initially to 12 ng per min. at the end of 20 min., the average length of a pheromone release period. Pheromone collections were also made from females of different ages, using a single tube of Porapak per female to collect pheromone for an entire night. The nightly mean release rate increased significantly with age, although the time spent releasing pheromone per night decreased significantly with age (to 6 days old).

Potential for evolution of resistance to pheromones: Interindividual and interpopulational variation in chemical communication system of pink bollworm moth

After an extensive examination of the release rates and blend ratios of pheromonal components emitted by field-collected femalePectinophora gossypiella (Saunders), we find no evidence of resistance to pheromones applied to cotton fields to disrupt mating. Females from fields with 3–5 years of exposure to disruptant pheromones as well as those from fields with only minimal exposure to disruptant pheromones emitted (Z,Z)-7,11-hexadecadienyl acetate at a rate of ca. 0.1 ng/min and (Z,E)7,11-hexadecadienyl acetate at ca. 0.06 ng/min. The ratio of pheromonal components was much less variable than the measured emission rate and was centered about a 61:39Z, Z to Z,E ratio. In contrast to the blend ratio emitted by females, the composition of the pheromonal blend used in monitoring populations and disrupting mating is centered about 50:50 Z,Z to Z.E. In general there was a remarkable consistency in the release rate and blend ratio among populations of females throughout southern California and those from a laboratory colony. It would appear that, although resistance to theP. gossypiella pheromone is still a very real possibility when it is used heavily in pest management as a mating disruptant, there are current agricultural practices and conditions which would hinder its development.

Maturation and senescence of an insect chemosensory response

Electroantennogram responses of male and femalePseudaletia unipuncta to the two major components of the presumed pheromone associated with the male anterior abdominal scent brushes vary with age. There is a postemergence period of maturation of responsiveness, followed by senescence. The age of maximum responsiveness differs according to the sex and to the compound tested.

Effects of gaster extract trail concentration on the trail following behaviour of the Argentine ant, Iridomyrmex humilis (Mayr)

Abstract In the Argentine ant, optimum trail following to gaster extracts was displayed to 0.1 and 1.0 equivalents/50 cm of circular trail. Trail following to airborne components was demonstrated when ants exhibited normal trail following behaviour while walking 3 or 6 mm below a 0.1 ant equivalent trail. However, at 8 or 12 mm separation, following ceased, indicating that the height of the active space was ca. 6–8 mm. The average horizontal distance from the centre of the trail at which ants exhibited following behaviour increased with concentration to 3–4 mm beyond the applied trail boundaries, indicating both an ability to follow airborne chemicals, and possibly a non-tolerance of excessively high concentration. Activity of 0.1 ant equivalent trails on filter paper declined to about half the original level by four hours; after eight hours, responses were significantly different from, but almost as low as, solvent controls.