The Environmental Monitoring of Methyl Eugenol, Naled and Dichlorvos During a Pest Trapping and Eradication Program
Abstract
The California Department of Food and Agriculture completed a three-phase study in 1988 to investigate the environmental fate of methyl eugenol, naled, and dichlorvos {DDVP), a degradation product of naled. The first phase of the study was planned to determine the feasibility of monitoring the three compounds during a routine pest eradication program. Once the feasibility of monitoring the three compounds was shown, the second-phase was planned to measure ambient air concentrations of the compounds during a fruit fly eradication. The third-phase was planned to determine if residues of methyl eugenol, naled, and DDVP were present in edible portions of fruit growing near fruit fly traps.
The first-phase was performed at a Plant Industry facility in Folsom, California. Air samplers. were placed 1 m and 25 m from a treated bait station. Air samples were collected for 4, 8, and 24 hours on day O, 1, and 7 after the bait station was treated. Methyl eugenol was unmeasurable after day O except for the 24 hour sample collected 1 m from the bait station on day 1. Naled was not dete~3ed. DDVP was found on all sampling days and decreased to less than 1 ng m by day 7. Results from the first-phase were used to design the second-phase.
The second-phase was performed during the oriental fruit fly eradication program in Hacienda Heights {Los Angeles County) in the fall of 1988. Four-hour ambient air samples were collected during the first and fourth applications of bait, at four and six sites, respectively. During application one, methyl eugenol decreased significantly over days O, 1, and 5 (p < 0.001) and ranged from 323 to 1050 ng m on day Oto none detected on day 5. During application four, there was no significant decrease in methyl eugenol concentration over days O through 4 but the decrease in DDVP concentration at the same sites was significant (p < 0.001).
The third-phase was performed in Sacramento County in September 1988. Whole citrus fruit samples were collected from four sites. Methyl eugenol was found in two samples from site 1 and one sample from site 2. DDVP was found in two samples from site 1. A literature search was undertaken which showed methyl eugenol to be a naturally occurring compound in some citrus fruits. Additional monitoring will take place in 1989 to test additional fruit tree species for the presence of both DDVP and methyl eugenol.