Evaluation of bait effectiveness and chitin synthesis inhibitors against Solenopsis invicta
Date Issued
2006
Date
2006
Author(s)
Liu, Kelvin Jordan
DOI
zh-TW
Abstract
Solenopsis invicta is definitely one of the most serious invaded species of the world. It has caused countless economic loss and public health risk. Unfortunately, it was found at Taiwan in 2003. The government purposes to eliminate S. invicta from Taiwan, and large amount of bait and contact insecticide has been applied in the field. In the meanwhile, some effort is still trying to screen out more effective bait to control S. invicta. However, ants can’t reproduce generations in laboratory. Under such condition, the simulative laboratory test using few laboratory populations is necessary to replace the field experiment and laboratory test with whole-colony. But bait effectiveness evaluation under laboratory condition is not constructed thoroughly.
50 workers (mix of minors and majors) is replaced in one box, and fed with soybean oil for one week under 27℃. The feeding rate is 16.3 ± 0.5 mg. Comparing to the room light condition (400 Lux), the feeding rate is 10.3 ± 0.9 mg and significantly lower with dim light (4 Lux). When tested with 0.05% hydramethylnon dissolved in soybean oil and consisted with 5 - 25 4th instar larvae more, the feeding rate is not significantly different at each larval number. But if 30, 50 or 75 workers set with 15 larvae, the feeding rate is positive to the worker number. Comparing to 50 workers alone, the LT50 is slightly shorter when set with up to 25 larvae, but no significantly difference; the LT50, however, is significantly shorter when set with 5 and 15 pupae. Above all, it is nearly not related between feeding rate and LT50, and the R2 is as low as 0.0394. Three sets of workers: 100, 50 and 25, with 0 – 20 larvae are fed with solid 0.00015% fipronil bait. The LT50 is significantly shorter in the treatment with larvae. The result shows that although adult workers can’t eat solid particle but still can been effected by bait. The existence of larvae can digest the solid food and transfer the chemical.
The chitin synthesis inhibitor is a kind of agro-chemical with slow action and is safe to mammal. It has been widely used against various insect pests, especially on termites, but is not used on ants. The death rate over 30days of workers is lower than 20% by feeding 0.1% - 2.5% diflubenzuron, triflumuron and hexaflumuron dissolved in soybean oil. No direct toxicity is observed on workers. As a single colony as an experimental unit, colonies are fed with 0.5 – 2.5% diflubenzuron bait. Only 1% diflubenzuron treatment shows significant reduction of population index over 12 weeks observation. Reduction of larvae is observed in most colonies, but not on workers. All treated colonies start to recover after the 10th week. 4th instar larvae fed with diflubenzuron do not reveal adverse effect on their digest system but shows delay in pupation. As the result, chitin synthesis inhibitors are not much effective to S. invicta.
Subjects
入侵紅火蟻
幾丁質合成抑制劑
室內評估
餌劑
Solenopsis invicta
chitin synthesis inhibitor
laboratory evaluation
bait
SDGs
Type
thesis
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