R. M. Trimble

Geographic Variation in Pheromone Chemistry, Antennal Electrophysiology, and Pheromone-Mediated Trap Catch of North American Populations of the Obliquebanded Leafroller

Abstract The total and relative amounts of (Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac), (Z)-11-tetradecen-1-ol (Z11-14:OH) and (Z)-11-tetradecenal (Z11-14:Al), and the EAG response of male antennae to these pheromone gland compounds were compared in laboratory reared Choristoneura rosaceana Harris (Lepidoptera: Tortricidae) from British Columbia, Michigan, Ontario, New York, and Quebec. A field trapping experiment was conducted in each of these locations to determine the effect of Z11-14:Al on the numbers of moths captured. The amount of each of the four pheromone-gland compounds declined successively in moths from British Columbia, Quebec, Ontario, Michigan, and New York. The relative amount of Z11-14:Ac was greatest in moths from New York and smallest in moths from Ontario, whereas the relative amount of E11-14:Ac was greatest in moths from Ontario and smallest in moths from British Columbia. Moths from Ontario, Quebec, British Columbia, Michigan, and New York contained decreasing relative amounts of Z11-14:OH and Z11-14:Al. There was a trend of increasing antennal sensitivity to each of the four pheromone-gland compounds in moths from New York, Michigan, Ontario, Quebec, and British Columbia. The addition of 1% Z11:Al to a three compound blend of Z11-14:Ac, E11-14:Ac and Z11-14:OH (97:2:1) resulted in a >twofold increase in average trap catch in British Columbia, Ontario, and Quebec; this compound had no effect on trap catch in Michigan or New York.

Identifying (E)-4,8-Dimethyl-1,3,7-Nonatriene Plus Acetic Acid as a New Lure for Male and Female Codling Moth (Lepidoptera: Tortricidae)

ABSTRACT Laboratory and field studies were conducted to measure the responses of adult codling moth, Cydia pomonella (L.), to several plant volatiles presented alone and in combination with acetic acid. Plant volatiles included ethyl (E,Z)-2,4-decadienoate (pear ester), (E)-β-farnesene, (Z)-3-hexenyl acetate, ± farnesol, and (E)-4,8-dimethyl-l,3,7-nonatriene (DMNT). Male codling moth exhibited upwind behavioral responses to each compound in flight tunnel tests with acetic acid > DMNT > ± farnesol > (Z)-3-hexenyl acetate > pear ester > (E)-β-farnesene. In apple orchards, however, only pear ester was an effective lure when used alone with clear pane traps. Choice tests in a flight tunnel with delta traps baited with DMNT plus acetic acid caught significantly more male and females than unbaited traps and significantly more females than DMNT-baited traps. Combining pear ester or DMNT loaded in septa lures with separate vials containing acetic acid significantly increased both male and female moth catch compared with the plant volatile alone, acetic acid alone, and unbaited pane traps in field trials. Similar results were not obtained with the other three plant volatiles. Septum loadings of 1 and 10 mg with either pear ester or DMNT in combination with acetic acid caught similar numbers of moths in orange delta traps. Sixty to 75% of the moths captured in traps baited with DMNT plus acetic acid were females. Moth catches in traps baited with DMNT plus acetic acid were ≈40% of catches in similar traps baited with pear ester plus acetic acid.

Relative Attractiveness of Natural and Synthetic Pheromone of Three Tortricid Tree Fruit Pests

Abstract The relative attractiveness of natural and synthetic pheromone of the obliquebanded leafroller, Choristoneura rosaceana (Harris), the codling moth, Cydia pomonella (L.), and the oriental fruit moth, Grapholita molesta (Busck), was compared in apple orchards. A piezoelectric sprayer was used to emit the main and selected minor pheromone compounds at an equal rate from two adjacent traps, one baited with natural and the other baited with synthetic pheromone. The average number of moths captured in traps baited with natural C. rosaceana pheromone was two times greater than the average number captured in traps baited with synthetic pheromone, and the average number of moths captured in traps baited with natural C. pomonella pheromone was four times greater than the average number captured in traps baited with synthetic pheromone. The average number of moths captured in traps baited with natural G. molesta pheromone was two times greater than the average number captured in traps baited with synthetic pheromone; however, the difference was not statistically significant. The results suggest that more effective synthetic pheromone formulations could be developed for monitoring C. rosaceana, C. pomonella and G. molesta, and for orientation disruption of C. rosaceana and C. pomonella.

Sex Pheromone of Grape Berry Moth (Lepidoptera: Tortricidae)

Abstract Pheromone gland extracts of grape berry moth females, Endopiza viteana Clemens, contain the main pheromone component, Z9–12Ac, at ≈1.2 ng per female, together with both geometric isomers of 11–14Ac, and a number of saturated acetates and alcohols of the chain length 12–16. The analogous alcohol, Z9–12OH, was found in some gland extracts. Trap capture of males was significantly increased by adding 0.5 or 2 μg of Z11–14Ac to 10 μg of the main compound, Z9–12Ac; whereas, adding 0.5 or 2 μg of E11–14Ac had no significant effect. In contrast, the addition of 5% Z9–12OH to the main compound resulted in a strong reduction in trap capture. Traps baited with a blend of Z9–12Ac and its geomeric isomer, E9–12Ac, which was not detected in gland extracts, were significantly less attractive than traps baited with blends of Z9–12Ac and Z11–14Ac. Knowledge of pheromone components and antagonists is essential for development of the mating disruption technique. The compounds identified in E. viteana are behaviorally active in the three most important tortricid pests of grape, Vitis vinifera (L.), in Europe. It may thus be possible to use a single blend of synthetic pheromone for control of several species.

Electrophysiological and Behavioral Responses of Oriental Fruit Moth to the Monoterpenoid Citral Alone and in Combination with Sex Pheromone

ABSTRACT The monoterpenoid citral synergized the electroantennogram (EAG) response of male Grapholita molesta (Busck) antennae to its main pheromone compound Z8–12:OAc. The response to a 10-µg pheromone stimulus increased by 32, 45, 54, 71 and 94% with the addition of 0.1, 1, 10, 100 and 1,000 µg of citral, respectively. There was no detectable response to 0.1, 1, or 10 µg of citral; the response to 100 and 1,000 µg of citral was 31 and 79% of the response to 10 µg of Z8–12:OAc. In a flight tunnel, citral affected the mate-seeking behavior of males. There was a 66% reduction in the number of males orientating by flight to a virgin calling female when citral was emitted at 1,000 ng/min ≈1 cm downwind from a female. Pheromone and citral induced sensory adaptation in male antennae, but citral did not synergize the effect of pheromone. The exposure of antennae to 1 ng Z8–12:OAc/m3 air, 1 ng citral/m3 air, 1 ng Z8–12:OAc + 1 ng citral/m3 air, or to 1 ng Z8–12:OAc + 100 ng citral/m3 air for 15 min resulted in a similar reduction in EAG response of 47–63%. The exposure of males to these same treatments for 15 min had no effect on their ability to orientate to a virgin calling female in a flight tunnel. The potential for using citral to control G. molesta by mating disruption is discussed.

Relative Attractiveness of Incomplete and Complete Blends of Synthetic Pheromone to Male Obliquebanded Leafroller (Lepidoptera: Tortricidae) Moths in a Flight Tunnel and in Apple Orchards: Implications for Sex Pheromone–Mediated Mating Disruption of This Species

Abstract The relative attractiveness of synthetic Choristoneura rosaceana (Harris) pheromone consisting of the major compound Z-11-tetradecenyl acetate (Z11–14:OAc), or the major compound plus one, two, or all three of the minor compounds E-11-tetradecenyl acetate (E11–14:OAc), Z-11-tetradecenol (Z11–14:OH), and Z-11-tetradecenal (Z11–14:Ald), in amounts similar to those in the natural pheromone, was compared in a flight tunnel and in apple orchards. In the flight tunnel, there was an increase in the proportion of moths that were activated when E11–14:OAc was combined with the main compound, but no detectible additional increases in response with the addition of Z11–14:OH and Z11–14:Ald. The time required for activation was twice as long when using the major compound than when using the major compound and one or more of the minor compounds. There was a trend of increase in the proportion of males initiating the take-off, lock-on, close-in, and touchdown phases of upwind flight when progressively more complete blends were used. The time required for the initiation of these behavioral phases was statistically similar for each treatment. The proportion of moths landing at the pheromone source was 10 times greater when using the complete blend than when using the main compound alone. Similar results were obtained in apple orchards, where the four-compound blend was 17–55 times more attractive than the main compound. The superior attractiveness of the four-compound pheromone compared with the major compound, or to the major compound plus the minor compound E11–14:OAc, suggests that it would be the most effective synthetic pheromone if competitive attraction were an important mechanism of disruption in this species.

Differences in the relationship between sensory adaptation of antennae and concentration of aerial pheromone in the oriental fruit moth and obliquebanded leafroller (Lepidoptera: Tortricidae): implications for the role of adaptation in sex pheromone-mediated mating disruption of these species.

ABSTRACT The antennae of Grapholita molesta (Busck) are more susceptible to sex pheromone—induced sensory adaptation than the antennae of Choristoneura rosaceana (Harris). Adaptation is detectable in G. molesta at 1/1,000th the aerial concentration of pheromone (i.e., 5.0 × 10-7 ng Z8-12:OAc/ml air) that is required to induce detectable adaptation in C. rosaceana (i.e., 5.0 × 10-4 ng Z11–14:OAc/ml air). In addition, the predicted concentration of pheromone required to induce 50% adaptation in G. molesta (i.e., 1.2 × 10-3 ng Z8–12:OAc/ml air) after 15 min of exposure is only one sixth the estimated aerial concentration required to induce the same level of adaptation in C. rosaceana (i.e., 7.5 × 10-3 ng Z11–14:OAc/ml air) after 15 min of exposure. Sixteen percent and 28% adaptation of G. molesta antennae is predicted after 15 and 30 min of exposure to the equivalent of 1 ng Z8–12:OAc/m3 air (i.e., 1 × 10-6 ng Z8–12:OAc/ml air). The predicted level of adaptation in C. rosaceana antennae, however, is only 1.5 and 9.9% after 15 and 30 min of exposure, respectively, to the equivalent of 1 ng Z11–14:OAc/m3 air (i.e., 1 × 10-6 ng Z11–14:OAc/ml air). The approximately three-fold greater level of sensory adaptation in G. molesta antennae after 30 min of exposure to a pheromone concentration measured in pheromone-treated orchards (i.e., 1 ng/m3) may be one reason why this species is more readily controlled than C. rosaceana using mating disruption.

Sensory Adaptation of Antennae and Sex Pheromone-Mediated Flight Behavior in Male Oriental Fruit Moths (Leptidoptera: Tortricidae) After Prolonged Exposure to Single and Tertiary Blends of Synthetic Sex Pheromone

ABSTRACT Sensory adaptation has been measured in the antennae of male Grapholita molesta (Busck) after 15 min of exposure to its main pheromone compound (Z)-8-dodecen-1-yl acetate (Z8-12:OAc) at the aerial concentration of 1 ng/m3 measured in orchards treated with pheromone for mating disruption. Exposing males to this aerial concentration of Z8-12:OAc for 15 min, however, had only a small effect on their ability to orientate by flight to virgin calling females in a flight tunnel. Experiments were undertaken to determine if exposure to the main pheromone compound in combination with the two biologically active minor compounds of this species, (E)-8-dodecen-1-yl acetate (E8-12:OAc) and (Z)-8-dodecen-1-ol (Z8-12:OH) would induce greater levels of sensory adaptation and have a greater effect on male sexual behavior. The exposure of male antennae to 0.5 g/m3 air of one of the three pheromone compounds induced sensory adaptation to this compound and to the other two pheromone compounds demonstrating cross adaptation. Average percentage sensory adaptation to a pheromone compound was similar after 15 min of exposure to 1 ng/m3 air of Z8-12:OAc, or to 1 ng/m3 air of a 1:1:1 or 93:6:1 blend of Z8-12:OAc, E8-12:OAc, and Z8-12:OH. The exposure of males to 1 ng/m3 air of Z8-12:OAc or the two ratios of Z8-12:OAc, E8-12:OAc, and Z8-12:OH for 15 min had no effect on their ability to orientate to a virgin calling female. The implications of these results for the operative mechanisms of sex pheromone-mediated mating disruption of this species are discussed.

Relative Attractiveness of (10E)-Dodecen-1-yl Acetate and (4E,10E)-Dodecadien-1-yl Acetate to Male Spotted Tentiform Leafminers Phyllonorycter blancardella (F.)

The antennae of male spotted tentiform leafminers, Phyllonorycter blancardella, from Ontario, Canada, exhibited similar electroantennogram responses when stimulated with E10-12:Ac or E4,E10-12:Ac. In field trapping experiments, E10-12:Ac was two-fold or more attractive than E4,E10-12:Ac, and E4,E10-12:Ac did not enhance the attractiveness of E10-12:Ac. E4,E10-12:Ac has not been identified in the pheromone of P. blancardella and it is hypothesized that the structural similarity of this compound and E10-12:Ac, the major pheromone compound of this species, may be responsible for the electrophysiological and behavioral responses to E4,E10-12:Ac. The possible reasons for the disparity between the results of our field trapping experiments and those carried out in Nova Scotia, Canada, and Massachusetts, USA., where E4,E10-12:Ac was found to be two to four times more attractive to P. blancardella than E10-12:Ac, are discussed.