H. H. Shorey

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.

Nature of the Sound Produced by Drosophila melanogaster during Courtship.

The wing vibrations of courting male Drosophila melanogaster Meigen produced pulsations of sound, with each pulse apparently caused by 1 to 2 cycles of wing movement. The average repetition rate at 25�C was 29.8 pulses per second. The rate was dependent on temperature, increasing at 1.4 pulses per additional degree Celsius.

Haemolymph juvenile hormone esterase activity in synchronous last instar larvae of the cabbage looper, Trichoplusia ni

Weight and time of moult during the last instar of the cabbage looper (Trichoplusia ni) were examined and used to select last instar larvae that had similar rates of development. Haemolymph protein content and titres of haemolymph esterases hydrolyzing juvenile hormone I, juvenile hormone III, and α-naphthyl acetate were monitored during the last instar using these closely timed larvae. Juvenile hormone I and juvenile hormone III esterase profiles were very similar and differed markedly from the α-naphthyl acetate esterase and protein content profiles. Two major peaks of juvenile hormone esterase activity were observed, one before ecdysone release and the other just prior to pupal ecdysis. Juvenile hormone I was hydrolyzed 15 times faster than juvenile hormone III when assayed at 5 × 10−6 M.

Chemical Trail-Following by Flying Insects: A Mechanism for Orientation to a Distant Odor Source

An aerial trail of odorous pheromone molecules extends downwind from a female pink bollworm moth that is receptive for mating. Males apparently sense the boundaries of the trail during their characteristic zigzag flights across it. Contrary to previous beliefs, the mechanism by which the males steer toward the odor source does not require a sensing of wind direction.

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.

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).

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.

Dodecyl acetate, a second pheromone component of the cabbage looper moth, Trichoplusia ni.

Dodecyl acetate was identified as a second component of the sex pheromone ofTrichoplusia ni (Hübner). Dodecyl acetate comprised 9.6% by weight of the total pheromone [(Z)-7-dodecenyl acetate plus dodecyl acetate] extracted from glands and 7.3% by weight of the total pheromone evaporated from the surfaces of glands. Dodecyl acetate appears to function as a short-range pheromone component. Evaporation at female release rates of a 10∶90 mixture of dodecyl acetate and (Z)-7-dodecenyl acetate in the field caused a significantly greater percentage of males to land on the pheromone source, increased significantly the time they spent on the source, but decreased significantly the time they spent searching for the source when within 50 cm, as compared to (Z)-7-dodecenyl acetate alone.

Pheromone Concentration as a Mechanism for Reproductive Isolation between Two Lepidopterous Species.

Pheromone-releasing females of the closely related noctuid moths Trichoplusia ni and Autographa californica attract mainly males of their own species. Sex-pheromone-concentration specificity appears to be an important reproductive isolating mechanism for these two species. Apparently, both species utilize the same pheromone, cis-7-dodecenyl acetate, for mating communication, but T. ni utilizes a higher level than does A. californica. Traps releasing amounts of cis-7-dodecenyl acetate that are highly attractive for males of one of the species catch very few males of the other species.