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Susceptibility of Maconellicoccus hirsutus (Homoptera: Pseudococcidae) to methyl bromide
J Larry Zettler1, Peter A Follett, Richard F Gill
1USDA-ARS, Horticultural Crops Research Laboratory, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648, USA. lzettler@fresno.ars.usda.gov
Abstract:
Eggs, crawlers, early nymphs, late nymphs, and adults of the pink hibiscus mealybug, Maconellicoccus hirsutus (Green), were tested for their susceptibility to methyl bromide in 2-h laboratory fumigations at ambient conditions (25 degrees C, 95% RH). Dose-response tests indicated that the egg was the most susceptible life stage with an LC99 of 20.2 mg/liter. Based on probit analysis of dose-response data, no significant differences were observed among susceptibilities of the crawler, early stage or late stage nymphs, or adults at either the LC50 or LC99 level, but late stage nymphs were more tolerant than early stage nymphs in a separate paired comparison test. Confirmatory tests showed that a dose of 48 mg/liter methyl bromide, the USDA-Animal Plant Health Inspection Service treatment dose schedule for mealybugs at 21-26 degrees C, produced 100% mortality of all life stages. On the basis of these results, we conclude that the methyl bromide treatment schedule for mealybugs will provide quarantine security for M. hirsutus infesting commodities for export or import.
Insights
Methyl bromide fumigation effectively controls the pink hibiscus mealybug (Maconellicoccus hirsutus). A specific dose ensures 100% mortality across all life stages, providing quarantine security for imported and exported goods.
Area of Science:
- Agricultural Entomology
- Pest Management
- Chemical Toxicology
Background:
- The pink hibiscus mealybug (Maconellicoccus hirsutus) is a significant agricultural pest.
- Effective quarantine treatments are crucial for international trade to prevent pest dissemination.
Purpose of the Study:
- To determine the susceptibility of different life stages of Maconellicoccus hirsutus to methyl bromide.
- To evaluate the efficacy of the current USDA-APHIS methyl bromide treatment schedule for M. hirsutus.
Main Methods:
- Laboratory fumigations of M. hirsutus life stages (eggs, crawlers, nymphs, adults) with methyl bromide.
- Dose-response assays and probit analysis to determine lethal concentrations (LC50, LC99).
- Confirmatory tests using the USDA-APHIS standard treatment dose.
Main Results:
- Eggs were the most susceptible life stage (LC99 = 20.2 mg/liter).
- Crawlers, early nymphs, late nymphs, and adults showed similar susceptibility levels.
- The USDA-APHIS methyl bromide dose (48 mg/liter) achieved 100% mortality for all life stages.
Conclusions:
- Methyl bromide is highly effective against all life stages of M. hirsutus.
- The current USDA-APHIS methyl bromide treatment schedule provides effective quarantine security for M. hirsutus.
- This research supports the continued use of methyl bromide for quarantine purposes against this pest.