Washington Tree Fruit Research Commission

Research Reports

Optimization of chemical attractants for the spotted cutworm (2003)

FINAL PROJECT REPORT
WTFRC Project #
YEAR 0/0
Organization Project #
Title:Optimization of chemical attractants for the spotted cutworm
PI:Peter J. Landolt
Organization:USDA-ARS, Yakima Agricultural Research Laboratory, Wapato, WA
 PDF version of report

Objectives

1. Determine the best blend and dose of sex pheromone components for the spotted cutworm.

2. Document non-target moths captured in traps baited with spotted cutworm pheromone.

3. Determine the best blend of floral compounds for trapping spotted cutworm moths.

 

Significant findings

1. Chemical analyses of female pheromone glands showed the consistent presence of three compounds: (Z)-7-tetradecenyl acetate, (Z)-5-tetradecenyl acetae, and (Z)-7-tetradecenol, with (Z)-7-tetradecenyl acetate the major component.
2. Field tests of pheromone compounds indicated co-attractiveness of  (Z)-5-tetradecenyl acetate and (Z)-7-tetradecenyl acetate, and inhibitory effects of (Z)-7-tetradecenol.
3.Field tests of single, two and multi-component blends of floral chemicals did not indicate attractiveness of any material comparable to that already attained with acetic acid and 3-methyl-1-butanol.  Weak attractiveness to phenylacetaldehyde was demonstrated.

Methods

Eggs were obtained from female spotted cutworms captured in a light trap at the USDA.  Larvae were reared on a standard pinto-bean based diet for noctuid moths to obtain unmated females in the laboratory.  Abdominal tips including the pheromone gland were cut and extracted in organic solvent, then analyzed by GC-MS to obtain preliminary identifications of compounds.  Structures were confirmed by comparison to synthetic standards, both using spectroscopic data and GC retention times on polar and non-polar columns.

Pheromone chemicals tested were formulated in pre-extracted red rubber septa at one milligram loads, and placed in Universal moth traps in apple orchards for evaluation of attractiveness.  Three experiments were conducted with pheromone chemicals.  The first compared single chemicals found in gland extract to two and the three component blend to determine the importance of each chemical found to attractiveness.  The second and third tests were evaluations of ratios of the two active components, to determine the significance of the relative amounts of chemicals in the lures.
 

Floral chemicals evaluated were based on two USDA patented floral lures and included phenylacetaldehyde, methyl jasmonate, linalool, limonene, methyl-2-methoxy benzoate, 2-phenylethanol, and methyl salicylate.  These chemicals were loaded in 8 ml vials with 6 mm diameter holes in the lids. Vials were placed in the bottom of Universal moth traps for field testing in apple orchards.  Three tests were conducted; 1) each chemical tested singly in comparison to an unbaited trap, 2) two component blends made up of phenylacetaldehyde and each of the other chemicals, and 3) the three and 5 component blends of the two floral blends (from honeysuckle and Gaura flowers).

Results and discussion

Analyses of female abdominal glands indicated the presence of three compounds that are similar to moth sex pheromone chemicals.  These are (Z)-7-tetradecenyl acetate, (Z)-5-tetradecenyl acetate, and (Z)-7-tetradecenol.  Ratios of these three chemicals in gland extracts were about 100 to 1 to 1 for the three chemicals respectively.
Field tests indicated some attractiveness of (Z)-7-tetradecenyl acetate alone and much stronger attractiveness of the two component combination of (Z)-7-tetradecenyl acetate and (Z)-5-tetradecenyl acetate.  The addition of (Z)-7-tetradecenol appeared to reduce attractiveness of those two compounds.

 

Table 1. Numbers of male spotted cutworm moths captured in Universal moth traps baited with different pheromone lures.

Chemicals tested                                                           Mean + SE males captured

No chemicals                                                                                                    0.00 + 0.00

 

Z-7-14:AC                                                                                                        0.55 + 0.14

 

Z-7-14:AC/Z-5-14AC                                                                            9.80 + 2.62

 

Z-7-14:AC/Z-7-14:OH                                                                           0.20 + 0.12

 

Z-7-14AC/Z-5-14:AC/Z-7-14:OH                                   2.10 + 0.51

 

Further evaluation of the two component pheromone, (Z)-7-tetradecenyl acetate and (Z)-5-tetradecenyl acetate, at different ratios, indicated an optimum response at a ratio of 9 to 1, although there was not much variation in the responses over the range of ratios tested (Table 2).

 

Table 2. Numbers of male spotted cutworm moths captured in Universal moth traps baited with different ratios of  Z-7-14AC/Z-5-14:AC lures, at a 1 mg load per septum.

Ratio of Z-7-14AC/Z-5-14:AC                                       Mean + SE males captured

100 to 0                                                                                                            0.25 + 0.18

 

100 to 0.3                                                                                                          2.65 + 1.19

 

100 to 1                                                                                                            3.75 + 0.80

 

100 to 3                                                                                                            3.20 + 0.79

 

100 to 10                                                                                                           4.55 + 1.18

 


Testing of single component floral lures indicated only very weak attraction to phenylacetaldehyde, and no significant response to other chemicals tested.  Addition of each of the other floral compounds to phenylacetaldehyde did not significantly increase numbers of spotted cutworm moths trapped over what was obtained with phenylacetaldehyde alone.
Results of this work provide recommendations for the chemicals to be used for formulating pheromone lures for the spotted cutworm, as well as lure component loads.   Such lures might be used as a means of monitoring seasonal phenology or emergence of spotted cutworm in orchards.

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