Spinosad resistance in field populations of melon fly, Zeugodacus cucurbitae (Coquillett), in Hawaii
Journal
Pest Management Science
Journal Volume
77
Journal Issue
12
Pages
5439-5444
Date Issued
2021
Author(s)
Abstract
BACKGROUND: Control of Zeugodacus cucurbitae, a serious agricultural pest worldwide, often includes or is dependent on the use of spinosad-based insecticides. This is especially the case in Hawaii, where GF-120, a protein bait containing spinosad as the active ingredient, has been in use as a key integrated pest management (IPM) tool against this Tephritid for the last two decades. Here, we report on resistance to spinosad [resistance ratios (RRs) and median lethal concentration (LC50)] in Hawaii's populations of Z. cucurbitae. RESULTS: High resistance was found in populations from three farms on Oahu (RR?=?102–303; LC50?= 191–567 mg L–1) and in a population from Maui (RR?=?8.50; LC50?= 15.9?mg L–1). These will be problematic for control given that the most concentrated dilution ratio on the GF-120 label is 96 mg L–1 of spinosad (1 part GF-120 to 1.5 parts water). Background resistance in a na?ve wild population from the Island of Hawaii (RR?=?2.73; LC50?= 5.1?mg L–1) was relatively low compared with a spinosad-susceptible laboratory colony (LC50?= 1.87 mg L–1). Resistance in the three Oahu and one Maui populations declined over generations in the absence of spinosad but remained elevated in some cases. Moreover, melon flies collected from one of the Oahu farms 1 year after the cessation of spinosad use revealed high persistence of resistance. CONCLUSION: Compared with a 2008 survey of spinosad resistance, our findings indicate a 34-fold increase in resistance on one of the Oahu farms over 9 years. The evolution and persistence of high levels of resistance to spinosad in Z. cucurbitae in Hawaii highlights the need for alternative control tactics, particularly rotation of active ingredients. ? 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. ? 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Subjects
Cucurbitaceae fruits
GF-120
insecticide resistance
integrated pest management
protein bait
bait
fly
pest control
pesticide resistance
spinosad
wild population
Hawaii [United States]
Hawaiian Islands
Maui
Oahu
Bactrocera cucurbitae
Cucurbitaceae
insecticide
macrolide
animal
drug combination
Hawaii
Tephritidae
Animals
Drug Combinations
Insecticides
Macrolides
Type
journal article