CONTROL OF WESTERN CHERRY FRUIT FLY IN TART CHERRY WITH NEONICOTINOID INSECTICIDES

Diane G. Alston

Department of Biology, Utah State University, Logan, UT

Abstract: The efficacy of two neonicotinoid insecticides, thiacloprid (Calypso) and imidacloprid (Provado), were tested for control of western cherry fruit fly (Rhagoletis indifferens) in tart cherry as compared to an industry standard program (azinphosmethyl (Guthion) and carbaryl (Sevin)) and an untreated control. Insecticides were applied with an air blast sprayer (70-80 gpa) to 3-row-wide by 5-tree-long (60 ft x 60 ft) plots. In fruit harvest samples collected on 16 July, there was no fruit injury in Provado and Guthion/Sevin treatments, 0.08% injury in the Calypso treatment, and 2.75% injury in the untreated plots. Adult fly densities monitored with yellow sticky traps were high in all treatments (ranged from 195-272 cumulative flies per trap per treatment from 1 June to 26 July) with no differences among treatments.

Introduction

Calypso and Provado are neonicotinoid insecticides that act upon nicotinic acetylcholine receptors (nAChR) of insect nerve cells. Provado is registered on pome fruits for control of aphids, leafhoppers, leafminer, psylla, scale and mealybugs. Provado is not registered on stone fruits. Calypso is a new product, related to Provado, but not yet registered.

Methods

The trial was conducted in a 2.2 acre ‘Montmorency’ tart cherry orchard at the Utah State University research farm in Kaysville, UT. Insecticides were applied with an air blast sprayer at a rate of 70-80 gal of dilute spray per acre. Treatments were applied every 14 days for a total of three times each. Application dates were 1, 15, and 29 June.

Insecticide Treatments:

1. Calypso 4 F (thiacloprid; 40.4% ai; Bayer) @ 4 fl oz/acre

2. Provado 1.6 F (imidacloprid; 17.4% ai; Bayer) @ 8 fl oz/acre

3. Guthion 50 WP (azinphosmethyl; 50% ai; Bayer) @ 1.5 lb/acre (applied twice: 1 and

15 June) and Sevin XLR Plus (carbaryl; 44.1% ai; Rhone- Poulenc) @ 2 qt/acre

(applied once: 29 June)

4. Untreated Check

Results

Fruit Injury

Table 1. Percentage of fruit with western cherry fruit fly larvae (instars 1-3), exit holes and total injury (larvae + exit holes) on 26 June (100 fruit sampled per plot) and 16 July (1200 fruit sampled per plot).

Treatment

Early Harvest – June 26

(100 fruit sample)

Final Harvest – July 16

(1200 fruit sample)

 

Larvae

Exit holes

Total

Larvae

Exit holes

Total

Calypso 4 F

0 B

0

0 B

0.08 B

0 B

0.08 B

Provado 1.6 F

0 B

0

0 B

0 C

0 B

0 C

Guthion 50WP/Sevin XLR

0 B

0

0 B

0 C

0 B

0 C

Untreated

1.25 A

0

1.25 A

1.00 A

1.75 A

2.75 A

P>F

0.0001

-

0.0001

<0.0001

0.0003

<0.0001

Data were transformed as arcsine square root of proportions before analysis. Means were separated with Tukey’s studentized range test.

Adult Western Cherry Fruit Fly Densities

Figure 1. Mean adult fly capture per trap in the four treatments from 1 June to 26 July 2001.

Figure 2. Mean cumulative adult fly capture per trap from 1 June to 26 July 2001. There were no significant differences in cumulative numbers among treatments (P=0.6761).

Conclusions

Both neonicotinoid insecticides, Calypso and Provado, effectively controlled western cherry fruit fly in this trial (Table 1). Fruit injury in all insecticide treatments was significantly less than in the untreated control. The Guthion/Sevin and Provado treatments had no fruit injury at harvest, while the Calypso treatment had a very low level of 0.08% (1 infested fruit out of 1200 fruit sampled).

Adult fly densities were high in all treatments (Figs. 1 and 2). Mean cumulative numbers of flies per trap ranged from 195 to 272 for 1 June to 26 July (Fig. 2). Although cumulative fly captures in the Guthion/Sevin treatment were slightly lower than in the other treatments, there were no significant differences among treatments.

Fruit injury at harvest in the untreated plots was lower than expected (2.75%), especially given the high fly pressure. The small plot size and relatively small area of untreated trees in the orchard are likely explanations. The buffer rows were established to eliminate insecticide drift between plots and to create a greater reservoir of untreated trees to harbor fruit flies.