Use of Ethyl and Propyl (E,Z)-2,4-decadienoates in Codling Moth Management: Improved Monitoring in Bartlett Pear with High Dose Lures

ABSTRACT

The propyl and ethyl ester of (E,Z)-2,4-decadienoic acid were evaluated in gray halobutyl septa as kairomone enticements for both sexes of codling miller Cydia pomonella (L.). All studies were managemented in 'Bartlett' pear orchards with moderate to high codling miller adult population densities and treated with sex pheromone dispensers for mating disruption. Variable issues were obtained with kairomone loading experiments. Increasing the attraction loading to 40.0 mg of either the ethyl or propyl ester significantly increased male and total miller catch in separate experiments. However, in other ordeals with the ethyl ester no difference was ground in total moth catch in traps baited with 01 10 30 or 100 mg versus 400 mg allurements The 40.0 mg ethyl and propyl ester baits were both more effective than a 30 mg ethyl ester allurement and comparable to a sex pheromone temptation in detecting the beginning of codling miller flight in the spring generation. No difference was ground in moth catch between 400 mg propyl and ethyl ester decoys Significantly more females were caught in traps baited with 10 - 100 mg than with 10 - 1000 ?µg decoys loaded with the ethyl ester In general, kairomone decoys caught significantly fewer moths than sex pheromone lures

Key Words: Cydia pomonella, monitoring, kairomone, trapping

INTRODUCTION

Codling miller Cydia pomonella (L.) (Lepidoptera: Torticidae), is a worldwide, lock opener internal pest of pear, Pyrus communis L and adult populations in commercial orchards are typically monitored with traps baited with sex pheromone allurements (Riedl et al. 1986). Reliable adult monitoring is especially critical in orchards where codling miller is managed with applications of its sex pheromone for mating disruption (Knight 2002a). The sex pheromone treatment disrupts the attractiveness of the sex pheromone-baited trap, and traps can fail to alert fatal epidemic managers of potential problems. Efforts to improve the usefulness of traps in sex pheromone-treated orchards have included the use of high-dose enticements (Charmillot 1990) and an increased density of traps (Gut and Brunner 1996)

Identification of ethyl (E,Z)-2,4-decadienoate as a efficacious kairomone attractant for codling miller adults and larvae has allowed the unfolding of several new approaches to luckily monitor and manage this infection (Knight and Light 2001; Light et al. 2001) Ethyl (E,Z)-2,4-decadienoate is attractive to the pair sexes of codling moth, and traps can be used to assess the timing of female emerging see the verb and activity, as well as mating status. In addition, the attractiveness of the allurement is not strongly affected by means of the application of sex pheromones (Light et al. 2001) and the allurement can improve the prediction of local plague population densities (Knight 2002b).

Ethyl (E,Z)-2,4-decadienoate is a major volatile of ripe pear (Jennings et al. 1964) and is not base in immature fruit or pear-leaf volatiles (Miller et al. 1989 Scutareanu et al. 1997) An initial evaluation adviseed that ethyl (E,Z)-2,4-decadienoate might not be an effective attractant for codling miller adults in pear orchards (Light et al. 2001) However, this conclusion was based upon data collected with 1.0 mg allurements placed in three conventional 'Bartlett' orchards with high horizontals of codling moth (> 3 millers trapped per day with a sex pheromone bait and detectable levels of fruit injury). The relatively depressed attractiveness of the synthetic ethyl (E,Z)-2,4-decadienoate bait in these pear orchards was hypothesized to be to be paid to olfactory "masking" of the attraction by natural sources of ethyl (E,Z)-2,4-decadienoate released either from injured or ripening fruits or by dint of competing host volatiles (Light et al., 2001) A next to the first study found that lures loaded with 30 mg of ethyl (E,Z)-2,4-decadienoate were similar or more attractive than sex pheromone attractions in four cultivars of pear when orchards were treated with sex pheromones (Knight et al. 2005) Ethyl (E,Z)-2,4-decadienoate allurements performed similarly early and late in the season relative to a sex pheromone attraction in these cultivars suggesting that maturation of fruit was not an important factor affecting enticement attractiveness. Ethyl (E,Z)-2,4-decadienoate lures again performed poorly sole in 'Bartlett' pear orchards with high population densities of codling miller that were defined by catches in sex pheromone-baited traps exceeding 20 millers per season and the neighborhood of fruit injury (Knight et al. 2005)

Improvements in developing a more attractive kairomone allurement for codling moth in pear may involve optimizing its emission rate and/or the use of alternative attractants. Light et al. (2001) reported that ethyl (E,Z)-2,4-decadienoate loaded into gray halobutyl allurements was attractive at doses > 100 ?µg and the highest miller catches in walnut orchards occurr with 100 mg baits Studies testing doses of ethyl (E,Z)-2,4-decadienoate > 30 mg in pear have not been reported. Among the 23 volatile mingles tested by Light et al. (2001) solitary the blend of methyl and ethyl ester of ten-carbon acids were attractive to adult codling miller Within this group, methyl (E,Z)-2,4-decadienoate was ground to be somewhat attractive in one as well as the other apple and walnut orchards. This mix was also attractive to neonate codling miller (Knight and Light 2001). Unfortunately, the methyl ester is another constituting of ripe pears (Heinz et al. 1966 Shiota 1990) and its attractiveness to codling miller would also likely be influenced by the agency of competition with volatile fruit odors within the orchard.