Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 2, 1999
Publication Date: N/A
Interpretive Summary: The diamondback moth (DBM) is the most destructive pest of crucifers, occurring wherever they are planted throughout the world. Costs to manage this pest are approximately U.S. $1 billion annually. The DBM is difficult to control, in part because it has developed resistance to most chemical insecticides, including biologicals such as Bt. Pheromone traps commonly are use to monitor the seasonal occurrence and magnitude of diamondback populations: and in some cases, make decisions on when to apply insecticides for control. Around the world, various pheromone blends are used for capturing diamondback moth males in traps. To compound the situation, the blends often are dispensed from various types of delivery substrates. Scientists at the Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, investigated the response of DBM to sticky traps baited with different pheromone blends commonly used in different regions of the world. The blends were dispensed from red and gray rubber septa. Captures of male moths were correlated with gas chromatographic analyses of pheromone emission rates from the two types of septa. All mixtures released from gray septa captured more males than when released from red septa. With red septa, some blends captured more males than others. These results indicate that the choice of releaser substrate is of paramount importance in preparing lures for maximum trap capture of DBM. The results also suggest that heretofore reported regional biotypes of DBM may be an artifact of the choice of pheromone dispenser system used in various studies around the world. The results of this study will be extremely helpful to commercial formulators in standardizing trap lures for maximum effectiveness as monitoring tools for diamondback moth.
Technical Abstract: Field trap assays of diamondback moth, Plutella xylostella (L.), male response to its sex pheromone components were conducted conjointly with gas chromatographic measures of lure emissions delivered from gray and red rubber septa. The object was to correlate trap captures which are a gauge of male mixture perception with measures of actual emissions. All mixtures sreleased from gray septa captured more males than when released from red rubber septa. There was no statistically detectable difference between captures at any of the mixtures when emitted from gray septa. However, when emitted from red septa, a nominal 70 : 30 ratio of Z11-16:Al: Z11-16:Ac effected the capture of more males than either the nominal 50 : 50 or 64 : 28 ratios. The emitted ratios of Z11-16:Al and Z11-16:Ac, although variable, ranged between 0.6 : 1 to about 4 : 1. No statistical correlation was found, parametric or non-parametric, between the emission data and trap captures by any single component, group of components or a ratio of components. The data are discussed in relation to putative differences in reported biotypes found in different geographical regions.