E. R. Mitchell

Mating disruption of diamondback moth (Lepidoptera: Plutellidae) and cabbage looper (Lepidoptera: Noctuidae) in cabbage using a blend of pheromones emitted from the same dispenser.

Experiments were conducted in commercial plantings of cabbage in spring 1994 and 1995 to evaluate the efficacy of a blend of pheromones for diamondback moth, Plutella xylostella (Linnaeus), and cab...

Heliothis virescens: Attraction of males to blends of (Z)-9-tetradecen-1-ol formate and (Z)-9-tetradecenal

In field trapping experiments, 16∶1 and 32∶1 blends of (Z)-9-tetradecen-1-ol formate (Z-9-TDF) and (Z)-9-tetradecenal (Z-9-TDAL) caught as manyHeliothis virescens (F.) as 3 virgin females and virelure, the synthetic pheromone of this species [a 16∶1 mixture of (Z)-11-hexadecenal (Z-11-HDAL) and (Z)-9-tetradecenal]. Z-9-TDF and (Z)-7-dodecen-1-ol formate (Z-7-DDF) are structurally similar to Z-11-HDAL and Z-9-TDAL, respectively. The sensory input elicited by Z-9-TDF appears to substitute for the sensory input of Z-1 1-HDAL. In contrast, Z-7-DDF had no significant effect on catches of maleH. virescens when used alone, in combination with either Z-11-HDAL or Z-9-TDF as a bait in traps, or as a disruptant of pheromone communication via permeation of the atmosphere. Furthermore, Z-9-TDF may be a more stable and economical attractant forH, virescens males than is Z-1 1-HDAL.

Parasitism of Diamondback Moth (Lepidoptera: Plutellidae) Larvae by Cotesia plutellae (Hymenoptera: Braconidae) and Diadegma insulare (Hymenoptera: Ichneumonidae) in Cabbage Fields after Inundative Releases of C. plutellae

Cocoons of Cotesia plutellae (Kurdjumov) were released for nine consecutive wk along the margins of two commercial cabbage (Brassica oleracea var. bravo L.) fields near Bunnell, Flagler Co., FL, in...

Collection of Fall Armyworm (Lepidoptera: Noctuidae) Using Selected Pheromone Lures and Trap Designs

Two trap designs and three sources of commercially-produced pheromone lures were used to capture fall armyworm, Spodoptera frugiperda (J. E. Smith), males in silage corn and peanuts in north-centra...

Spodoptera exigua: mating disruption, measurement of airborne concentration of pheromone, and use of specialist receptor cell responses for comparison to female pheromone emission.

Field experiments were conducted to evaluate Shin-Etsu Yoto-con-S® ‘rope’ pheromone dispensers applied at different site densities in cotton to determine effficacy in disrupting sexual communication and mating of beet armyworm moths, Spodoptera exigua (Hübner); obtain atmospheric measurements of the disruptant pheromone components in and away from treated areas; and relate this information to estimates of the concentration of pheromone in the near vicinity of a calling virgin female moth. The number of pheromone-dispensing sites/ha ranged from 25 with 20 ropes/site up to a total of 247 sites with 2 ropes each. A total of 112 g pheromone of a 70:30 blend of (Z,E)-9,12-tetradecadien-1- ol acetate (ZETA) and(Z)-tetradecen-1-ol (Z9–14:OH) was applied/ ha. As few as 25 sites/ha effectively disrupted sexual communication by 91%, as measured by reductions of moth captures in traps baited with pheromone lures, and mating by beet armyworm females by 94% for at least 10 weeks post-treatment. The results compared favorably to an earlier large-scale field experiment in which beet armyworm larval populations were reduced 95% using 500 pheromone-dispensing sites/ha (two ropes/site) and 160 g total pheromone/ha. The airborne concentration of ZETA and Z9–14:OH measured within the pheromone-treated plots that disrupted mating was 1.5 × 1013 M and 1.2 × 1013 M, respectively. The airborne concentration of ZETA and Z9–14:OH in the vicinity of a female was estimated (by excision and electrophysiological methods) to range between 2.1 × 1011 M and 2.4 × 1012 M, respectively, in a 1.6 km / h (1 mph) wind speed. Thus, the average ZETA concentration in the treated plots was about 140 times less than that expected from a single female; the average Z9–14:OH in the treated plots was about 20 times less. The data support an argument that disruption of mating by beet armyworm resulted from an imbalance in sensory input because mating was almost completely disrupted in all of the plots for at least 10 weeks with a mixture of ZETA:Z9–14:OH that differed significantly with that from excised female sex pheromone glands. Estimates of these parameters provide a benchmark for the requisite pheromone concentration in the atmosphere to achieve a high level of mating disruption for beet armyworm and possibly other insect pest species.

Subtleties in Perception and Discrimination by Cabbage Looper Moths, Trichoplusia ni, of the two 14-carbon Acetate Sex Pheromone Components

Three compounds that are emitted by virgin female cabbage looper moths, Trichoplusia ni, (Z)-7-dodecenyl acetate (Z7–12:Ac), (Z)-7-tetradecenyl acetate (Z7–14:Ac), and (Z)-9-tetradecenyl acetate (Z9–14:Ac), are detected by antennal olfactory receptor neurons specialized to detect sex pheromone components. The principal evidence signifying that either or both of Z7–14:Ac and Z9–14:Ac have an effect on male behavior comes from an observed reduction in the numbers of males trapped by Z7–12:Ac paired with a six-component mixture. The evidence conforms to a hypothesis that either or both of these compounds are the basis for discrimination between the two mixtures. However, scant evidence for this hypothesis was obtained in paired-source laboratory wind-tunnel assays, even at airborne concentrations of Z7–14:Ac and Z9–14:Ac that ranged up to 1000× that emitted by a female. Furthermore, there was little evidence from single-source laboratory or field trap assays confirming that Z7–14:Ac and Z9–14:Ac at or above natural stimulus strengths modify the moths perception of Z7–12:Ac. The data suggest that discrimination of small mixture differences may not be resolvable within the confines of a wind tunnel.

Diamondback Moth (Lepidoptera: Plutellidae) in Cabbage: Influence of Initial Immigration Sites on Population Distribution, Density and Larval Parasitism

Examinations of cabbage plants in five fields near Bunnell, Flagler Co., FL, in spring 1995 showed that larvae of the diamondback moth, Plutella xylostella (L.), were more abundant on the field ends (perpendicular to cabbage rows) adjacent to weed-filled drainage ditches than the fields ends abutting wooded swamp areas. There were no significant differences in the numbers of diamondback moth larvae on cabbage plants on the ends next to other cabbage fields or at sites located within the interior of the fields. Cabbage heads rated for damage due to diamondback moth larvae at harvest showed a distributional pattern similar to that observed for diamondback moth larvae. Parasitism of diamondback moth larvae was not significantly different between field ends and interior fields. Cabbage damage ratings on field sides (parallel to cabbage rows) showed that no edge effect was detected on the sides abutting other cabbage fields, that edge effect only occurred on the first one or few rows on the sides adjacent to o...