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Evaluation of ethyl formate for management of both resistant and susceptible strains of Cryptolestes pusillus and Cryptolestes ferrugineus

Gu, Chunyuan (2020) Evaluation of ethyl formate for management of both resistant and susceptible strains of Cryptolestes pusillus and Cryptolestes ferrugineus. Other thesis, Murdoch University.

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Australian agricultural are facing growing challenge to biosecurity threats. Insect pests are a major issue negatively effecting both the quality of stored grain and consumer health. Fumigation is a widely used method for control of a variety of insect pests due to its high degree of efficacy and cost effectiveness. Phosphine is the main fumigant deployed for the control of stored grain insect pests. However, researcher has shown that most of the stored grain insect pests have developed resistance to phosphine, which has been leading to ineffective control of many important stored grain insect species like C. pusillus and C. ferrugineus. As a result, there is an urgent need to identify and evaluate an alternative fumigant. Ethyl formate is proposed as a viable alternative to phosphine due to its status as a registered food additive, favourable environmental properties and low toxicity to humans.

In comparison with all previous studies, fumigation experiments were conducted using a continuous flow-through laboratory process to maintain constant concentrations of ethyl formate and low levels of respiratory CO2 (<0.08%). The procedure minimised the effects of sorption by exposing test insects without media and minimised the effect of CO2 by use of continuous flow. The toxicity data of ethyl formate obtained from this experiment are more robust as the continuous flow-through system operated under a constant concentration of ethyl formate at a constant 25° C and 62.5% r.h. and low CO2 concentrations during the 6 h exposure period.

Ethyl formate as fumigant offers quick and higher efficient to kill both susceptible and resistant strains of C. pusillus and C. ferrugineus at lower dosage level. There was no significant different mortality between susceptible and resistant strains of C. pusillus e g., the observed Ct product at LD50=13.09 and 12.75 mg h/L and LD99.5=28.17 and 29.55 mg h/L, and for C. ferrugineus at LD50=13.11 and 13.26 mg h/L and LD99.5=29.28 and 28.22 mg h/L. Thus we can propose that toxicity of ethyl formate to both species of C. pusillus and C. ferrugineus and strains of phosphine susceptible and resistant is same, which also indicated that there is no cross resistance between ethyl formate and phosphine. Therefore, ethyl formate has great potential as grain fumigant for grain industry to manage C. pusillus and C. ferrugineus, particularly their resistant strains.

Item Type: Thesis (Other)
Murdoch Affiliation(s): Agricultural Sciences
Notes: Research Masters with Training
Supervisor(s): Agarwal, Manjree, Ren, YongLin and Wang, Penghao
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