Piyaphongkul, Jiranan (2013). Effects of thermal stress on the brown planthopper Nilaparvata lugens (Stal). University of Birmingham. Ph.D.
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Piyaphongkul13PhD.pdf
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Abstract
This study investigated the effects of heat stress on the survival, mobility, acclimation ability, development, reproduction and feeding behaviour of the brown planthopper Nilaparvata lugens. The critical information derived from the heat tolerance studies indicate that some first instar nymphs become immobilized by heat stress at around 30°C and among the more heat tolerant adult stage, no insects were capable of coordinated movement at 38°C. There was no recovery after entry into heat coma, at temperatures around 38°C for nymphs and 42-43°C for adults. At 41.8° and 42.5oC respectively, approximately 50% of nymphs and adults are killed. In a comparison of the acclimation responses between nymphs and adults reared at 23°C and acclimated at either 15 or 30°C, the data indicate that increases in cold tolerance were greater than heat tolerance, and that acclimation over a generation compared with a single life stage increases tolerance across the thermal spectrum.
The temperatures that kill around 50% of nymphs and adults also exert negative effects on development and longevity. The same exposures also lower fecundity and extend egg development time through a combination of mating groups, in which the greatest effects occur when both males and females have experienced sub-lethal heat stress. Likewise, exposure to their ULT50 reduced feeding activity in both life stages of N. lugens. The amount of honeydew excreted by females and males in the treated nymph and adult groups were 3-4x and 2-3x lower than in the equivalent control groups. Overall, sub-lethal heat stress extended egg development time, inhibited nymphal development, lowered fecundity and reduced feeding activity.
| Type of Work: | Thesis (Doctorates > Ph.D.) | |||||||||
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| Award Type: | Doctorates > Ph.D. | |||||||||
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| College/Faculty: | Colleges (2008 onwards) > College of Life & Environmental Sciences | |||||||||
| School or Department: | School of Biosciences | |||||||||
| Funders: | Other | |||||||||
| Other Funders: | Royal Thai Government Scholarship | |||||||||
| Subjects: | Q Science > QH Natural history | |||||||||
| URI: | http://etheses.bham.ac.uk/id/eprint/4097 |
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