The lethal and sub-lethal effects of lambda-cyhalothrin to the syrphid Episyrphus balteatus (Degeer) (Diptera: syrphidae)
The lethal and sub-lethal effects of lambda-cyhalothrin to the syrphid Episyrphus balteatus (Degeer) (Diptera: syrphidae)
This project examines the acute toxicity and sub-lethal effects of the synthetic pyrethroid lambda-cyhalothrin on the syrphid species Episyrphus balteatus. Using estimates of exposure it attempts to predict the risks for populations of syrphids exposed in winter wheat. The acute toxicity of lambda-cyhalothrin was determined for each life stage of E. balteatus and the effect of exposure during each stage on the number of individuals surviving from a hypothetical cohort of eggs through to reproductive adults was predicted. The Larva was found to be the most susceptible life stage, followed by the egg, adult and pupa. Consequently, larval exposure was predicted to give rise to the largest potential reduction in the next generation of syrphids. The effect of larval exposure to sub-lethal doses of lambda-cyhalothrin on development, adult fitness and longevity was also investigated. Treatment was found to give rise to dose-dependent increases in larval and pupal development times. The number and size of eggs dissected from females decreased with dose and treatment increased the pre-oviposition period and longevity of females. Whereas control fecundity, longevity and pre-oviposition tended to be independent of female weight, in treated females, fecundity and longevity were generally positively correlated with weight and pre-oviposition period was negatively correlated with weight. Repellency of ovipositing E. balteatus by lambda-cyhalothrin contaminated foliage was detected. In the laboratory, the level of oviposition was negatively correlated with dose and was significantly lower on foliage treated at 1/5 field rate and above. Under semi-field conditions, effects were confounded by dose-dependent reductions in aphid numbers and by female mortality. However, results indicated that the distribution of eggs was affected by the presence of lambda-cyhalothrin and that females preferentially laid eggs where residues were lower. The profile of spray deposition over a winter wheat crop canopy and individual plant parts was quantified.
University of Southampton
1994
Moyle, Justine Louise
(1994)
The lethal and sub-lethal effects of lambda-cyhalothrin to the syrphid Episyrphus balteatus (Degeer) (Diptera: syrphidae).
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This project examines the acute toxicity and sub-lethal effects of the synthetic pyrethroid lambda-cyhalothrin on the syrphid species Episyrphus balteatus. Using estimates of exposure it attempts to predict the risks for populations of syrphids exposed in winter wheat. The acute toxicity of lambda-cyhalothrin was determined for each life stage of E. balteatus and the effect of exposure during each stage on the number of individuals surviving from a hypothetical cohort of eggs through to reproductive adults was predicted. The Larva was found to be the most susceptible life stage, followed by the egg, adult and pupa. Consequently, larval exposure was predicted to give rise to the largest potential reduction in the next generation of syrphids. The effect of larval exposure to sub-lethal doses of lambda-cyhalothrin on development, adult fitness and longevity was also investigated. Treatment was found to give rise to dose-dependent increases in larval and pupal development times. The number and size of eggs dissected from females decreased with dose and treatment increased the pre-oviposition period and longevity of females. Whereas control fecundity, longevity and pre-oviposition tended to be independent of female weight, in treated females, fecundity and longevity were generally positively correlated with weight and pre-oviposition period was negatively correlated with weight. Repellency of ovipositing E. balteatus by lambda-cyhalothrin contaminated foliage was detected. In the laboratory, the level of oviposition was negatively correlated with dose and was significantly lower on foliage treated at 1/5 field rate and above. Under semi-field conditions, effects were confounded by dose-dependent reductions in aphid numbers and by female mortality. However, results indicated that the distribution of eggs was affected by the presence of lambda-cyhalothrin and that females preferentially laid eggs where residues were lower. The profile of spray deposition over a winter wheat crop canopy and individual plant parts was quantified.
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Published date: 1994
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Local EPrints ID: 458645
URI: http://eprints.soton.ac.uk/id/eprint/458645
PURE UUID: b520cbc3-633e-45aa-a7f2-ce34c6bb5e15
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Date deposited: 04 Jul 2022 16:52
Last modified: 04 Jul 2022 16:52
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Author:
Justine Louise Moyle
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