Adoption of mating disruption for controlling the grape berry moth, Endopiza viteana  (Clemens) (Lepidoptera, Tortricidae) in Ontario, Canada

R. M. Trimble

• Introduction
• Development and evaluation of mating disruption
• Registration and adoption of mating disruption
• Recommendations for increasing the adoption of mating disruption
• References

Key words - Sex pheromone, mating disruption, controlled release dispenser, viticulture, Endopiza viteana, Tortricidae, Lepidoptera

Introduction

The grape berry moth, Endopiza viteana  (Clemens), is the most important insect pest of grapes in eastern North America (Taschenberg et al. 1974) and has been recognized as a pest in the Niagara peninsula of Ontario since 1917 (Roberts & Simpson 1982a). In the Niagara region, E. viteana  has three generations of actively feeding larvae per year. The first, or spring generation, attacks flowers or newly set clusters of berries; the next two generations feed on developing fruit (Roberts & Simpson 1982a). There is considerable variation in the size of E. viteana  populations within the Niagara peninsula and consequently from two to six applications of organophosphorous insecticides have traditionally been used to control this pest (Roberts & Simpson 1982b).

Development and evaluation of mating disruption
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The sex pheromone of the grape berry moth was identified as (Z)-9-dodecenyl acetate (Z9-12Ac) (Roelofs et al. 1971) and the first studies on the feasibility of controlling E. viteana  by sex pheromone-mediated mating disruption were conducted from 1972 to 1987 in New York State vineyards (Dennehy et al. 1990).

In Canada, the efficacy of mating disruption for controlling E. viteana  was evaluated from 1987 to 1993 in the Niagara peninsula of Ontario. In the initial experiments, 1987 to 1989, the technique was tested in 0.7 to 1.4-ha plots in commercial vineyards with high-, moderate-, and low-density grape berry moth populations using several versions of a polyethylene, capillary-tube pheromone dispenser (Pacific Biocontrol Ltd., Vancouver, Oregon) (Trimble et al. 1991). In 1987 and 1988, each dispenser was loaded with 365 mg of (Z)-9-dodencenyl acetate, 40 mg of (Z)-11-tetradecenyl acetate and 45 mg of stabilizer. The dispensers had a field life of 4-5 months and were deployed at the recommended density of 250/ha. In 1989, each dispenser was loaded with 57 mg of (Z)-9-dodencenyl acetate, 6 mg of (Z)-11-tetradecenyl acetate and 7 mg of stabilizer. The field life of these dispensers was also 4 to 5 months and they were deployed at the recommended rate of 1 000/ha.

In a subsequent experiment, the technique was tested in ca. 1.5-ha plots of vines at two Niagara farms during five consecutive growing seasons, 1989 to1993, using Isomate® GBM pheromone dispensers (Pacific Biocontrol Ltd., Vancouver, Oregon) (Trimble 1993, Trimble unpubl.). In 1989, each dispenser was loaded with 135 mg of (Z)-9-dodencenyl acetate, 15 mg of (Z)-11-tetradecenyl acetate and 20 mg of stabilizer. The field life of these dispensers was 4 to 5 months and they were deployed at the recommended rate of 1 000/ha. During 1990 to 1993, each dispenser was loaded with 57 mg of (Z)-9-dodencenyl acetate, 6 mg of (Z)-11-tetradecenyl acetate and 7 mg of stabilizer. The field life of these dispensers was 2 months and they were deployed at the recommended rate of 1 000/ha twice each growing season.

The efficacy of mating disruption was evaluated by comparing captures of male moths in pheromone-baited traps and berry moth damage to grape clusters in plots treated with pheromone and in control plots treated with insecticide.

In the first experiments, average pheromone dispenser release rates ranged from 20 to 32 mg/ha/hr and pheromone-baited trap catches were reduced by 92% or more in plots treated with pheromone. Treatment with pheromone significantly reduced damage (i.e. percentage infested clusters) compared with an untreated control in each of two tests, and provided control as good as or better than an insecticide control programme in two of four tests. In the five-year experiment, the average rate of release of pheromone ranged from 29 to 37 mg/ha/hr and pheromone-baited trap catches were reduced by more than 99% in plots treated with pheromone. At one farm (Farm 1), insecticides provided better control than pheromone during 1989, but during the next four years, 1990 to 1993, only small differences were observed between methods (Table 1). At the other farm (Farm 2), mating disruption provided control as good as or better than insecticides during the 5-year-study (Table 1).

The evaluation of another pheromone dispenser, Decoy® GBM (Agrisense, Fresno, California), for use in controlling E. viteana  by mating disruption was completed in Niagara peninsula vineyards by Coopermill Ltd. of Madoc, Ontario, from 1987 to 1991 (JB Hastings pers. comm.). However, the results of this evaluation have not been published in the scientific literature.

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Table 1 Percentage grape clusters infested with E. viteana  at harvest in pheromone- and insecticide-treated plots at two Niagara peninsula farms, 1989 to 1993

Registration and adoption of mating disruption
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Decoy® GBM, a polymer-matrix-gel pheromone dispenser (Agrisense, Fresno, California) was registered in Canada in 1992 for controlling E. viteana  by mating disruption. During the four-year period 1992 to 1995, 23 to 26 growers used this product. The total area treated with Decoy GBM during this period did not exceed 200 ha, or 4% of the ca. 5 400 ha of commercial vineyard in the Niagara peninsula. During the 1996 growing season, 18 growers treated a total of ca. 140 ha of vineyard (JB Hastings pers. comm.).

The most probable reasons for the low rate of adoption of mating disruption for controlling E. viteana  are the relative costs of insecticide and Decoy GBM, the method of applying the pheromone and the method that has been used to promote the use of mating disruption. The cost of the insecticide required for a three spray control programme on one ha of vineyard using one of the six currently recommended insecticides (Anonymous 1996) ranged from $ Can 45 to 210 during the 1995 growing season (Table 2.).

Niagara peninsula grape growers are discouraged from using the pyrethroid insecticides permethrin or cypermethrin, and the carbamate insecticide carbaryl, because they are toxic to predaceous mites, and their repeated use can result in outbreaks of the European red mite, Panonychus ulmi (Koch). Therefore, azinphosmethyl, phosmet and diazinon are the most commonly used insecticides for controlling E. viteana.The cost of using Decoy GBM on one ha of vineyard during the 1995 growing season was from $ Can 196 to 249, depending on whether the grower purchased the pheromone dispensers with or without application and monitoring services (JB Hastings pers. comm.) (Table 2).

Table 2 Cost of E. viteana  control during the 1995 growing season by a three-spray insecticide programme and by mating disruption, using Decoy® GBM

Therefore, during the 1995 growing season, the cost of the pheromone dispensers required for use in mating disruption was 2.4 to 3.5 fold greater than the cost of the insecticide for a three-spray grape berry moth control programme. Decoy GBM must be applied by hand at a rate of 1000 dispensers/ha and the cost of performing this task, whether by the supplier or the grower, is viewed as an additional cost compared to using insecticide. This is because insecticides for E. viteana  control are generally applied as a sprayer tank mix with fungicides for disease control. The use of sex pheromone-baited traps as an indirect measure of the effectiveness of mating disruption, i.e. monitoring (Table 2), is an important component of the grape berry moth mating disruption programme (JB Hastings pers. comm.). However, this component of the programme is also regarded as an additional cost compared to using insecticides. Although sex pheromone-baited traps are used to acquire information that is used to time the application of insecticide sprays, this service has been provided free of charge by the Ontario Ministry of Agriculture, Food and Rural Affairs.

Another reason that mating disruption has not been widely adopted is that it has been promoted as an environmentally friendly alternative to the use of insecticides for controlling E. viteana  and grape growers, in general, have not regarded this as a benefit to their grape growing business.

Recommendations for increasing the adoption of mating disruption
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The use of mating disruption for controlling the grape berry moth in Niagara peninsula vineyards would likely be more widely adopted if the technique was cost-competitive with using insecticides and if it was promoted as an insecticide resistance-management tool for use in a sustainable, cost-effective pest management programme. The cost of using mating disruption would be reduced if it could be applied using conventional pesticide application technology. Microencapsulated formulations of pheromone can be applied with many types ground spraying equipment (Hall & Marrs 1989). The availability of a sprayable grape berry moth pheromone would enable growers to apply pheromone as a tank mix with the fungicides that are applied at approximately fortnightly intervals under Niagara peninsula growing conditions (Anonymous 1996).

Organophosphorous insecticides like azinphosmethyl, phosmet and diazinon have be used almost exclusively to control E. viteana  in Niagara vineyards for the last 30 years. Although there are no published reports of insecticide resistance in this pest, organophosphorous insecticide-resistance has be reported in other tortricid fruit pests such as the codling moth, Cydia pomonella (L.) in Australia (Thwaite et al. 1993) and the western U.S.A. (Varela et al. 1993; Knight et al. 1994), and the Oriental fruit moth, Grapholita molesta (Busck) in South Africa (Barnes & Blomefield, this volume). The fungus Botrytis cinerea Pers. has developed resistance to fungicides in Niagara peninsula vineyards (Northover & Matteoni 1986; Northover 1988) and therefore Ontario grape growers are aware of the potential for economic loss often associated with pesticide resistance. For this reason, mating disruption would be more readily accepted as a control strategy for grape berry moth control if it was promoted as part of a proactive, insecticide resistance-management programme instead of as a replacement for insecticides.

References
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Anonymous (1996) 1996/1997 Fruit production recommendations. Publication 360, Ministry of Food, Agriculture and Rural Affairs, Ontario

Dennehy TJ, Roelofs WL, Taschenberg EF, Taft TN (1990) Mating disruption for control of grape berry moth in New York vineyards, pp. 223-240 in R Ridgway, RM Silverstein, M Inscoe (eds.) Behavior-modifying Chemicals for Insect Management: Applications of Pheromones and Other Attractants. Marcel Dekker, New York

Hall DR, Marrs GJ (1989) Microcapsules, pp. 199-248 in AR Jutsum RFS Gordon (eds.) Insect Pheromones in Plant Protection. Wiley, New York

Knight AL, Brunner JF, Alston D (1994) Survey of azinphosmethyl resistance in codling moth (Lepidoptera: Tortricidae) in Washington and Utah. J econ Entomol 87, 285-292

Northover J (1988) Persistence of dicarboximide-resistant Botrytis cinerea in Ontario vineyards. Can J Plant Pathol 10, 123-132

Northover J, Matteoni JA (1986) Resistance of Botrytis cinerea to benomyl and iprodione in vineyards and greenhouses after exposure to the fungicides alone or mixed with captan. Plant Disease 70, 398-402

Roberts WP, Simpson CM (1982a) Pest management programme for grapes series: Grape berry moth on the Niagara peninsula. Ontario Ministry of Agriculture and Food, Agdex 212/632

Roberts WP, Simpson CM (1982b) Pest management programme for grapes series: Monitoring and predicting spray dates for the grape berry moth on the Niagara peninsula. Ontario Ministry of Agriculture and Food, Agdex 212/632

Roelofs WL, Tette JP, Taschenberg EF, Comeau A (1971) Sex pheromone of the grape berry moth: identification by classical and electro-antennogram methods and field tests. J Ins Physiol 17, 2235-2243

Taschenberg EF, Cardé RT, Roelofs WL (1974) Sex pheromone trapping and mating disruption for control of redbanded leafroller and grape berry moths in vineyards. Environ Entomol 3, 239-242

Thwaite WG, Williams DG, Hately AM (1993) Extent and significance of azinphos-methyl resistance in codling moth in Australia, pp. 166-168 in Pest Control & Sustainable Agriculture. CSIRO, Australia

Trimble RM (1993) Efficacy of mating disruption for controlling the grape berry moth, Endopisa viteana (Clemens) (Lepidoptera: Tortricidae), a case study over three consecutive growing seasons. Can Entomol 125, 1-9

Trimble RM, Pree DJ, Vickers PM, Ker KW (1991) Potential of mating disruption using sex pheromone for controlling the grape berry moth, Endopiza viteana  (Clemens) (Lepidoptera:Tortricidae) in Niagara Peninsula, Ontario vineyards. Can Entomol 123, 451-460

Varela SC, Welter SC, Jones VP, Brunner JF, Riedl H (1993) Monitoring and characterization of insecticide resistance in codling moth (Lepidoptera: Tortricidae) in four western states. J econ Entomol 86, 1-10
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