Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak

The rice yellow stem borer, Scirpophaga incertulas (Walker) is an important pest of rice in Sarawak, Malaysian Borneo. For a better management of this pest, it is crucial to understand its biology and also other aspects such as the oviposition behaviour and the genetic structure which is unknown. Th...

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Main Author:	Nur Najwa, Hamsein
Format:	Thesis
Language:	English
Published:	2021
Subjects:	Q Science (General) QK Botany QL Zoology S Agriculture (General)
Online Access:	http://ir.unimas.my/id/eprint/34982/4/Nur%20Najwa%20Hamsein.pdf
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id	my-unimas-ir.34982
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spelling	my-unimas-ir.349822023-04-10T04:04:39Z Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak 2021 Nur Najwa, Hamsein Q Science (General) QK Botany QL Zoology S Agriculture (General) The rice yellow stem borer, Scirpophaga incertulas (Walker) is an important pest of rice in Sarawak, Malaysian Borneo. For a better management of this pest, it is crucial to understand its biology and also other aspects such as the oviposition behaviour and the genetic structure which is unknown. The observation on the life cycle of S. incertulas was carried out under laboratory condition. The incubation period ranged between 7–9 days. The larval duration completed in 38–42 days. The pupal duration ranged 7–10 days. The female moths longevity was longer than the male moths with an average 4.30 ± 0.90 and 3.70 ± 0.50 days respectively. In this study, rearing of S. incertulas under laboratory condition seems to be not feasible. Mortality was the highest at larval stages hence resulted in low adult emergence. For the study on S. incertulas oviposition behaviour, several aspects of its behaviour on Sarawak rice landraces were observed in a net house experiment. A total of 180 females of S. incertulas were given access to six different rice landraces at three plant ages. The results indicated that rice plants at four-month old were strongly preferred for oviposition regardless of landraces. This is probably because of the height of the older plants as compared to the younger plants. Plants with high stature is easier to be identified by flying moths, making it preferable for the moths to rest and oviposit. The vertical distribution of egg masses on plant were varied. Oviposition on leaf surfaces showed a clear preference on the abaxial leaf surface. To analyze the genetic relatedness of S. incertulas populations, four ISSR and primers and two RAPD primers were used. The combined ISSR and RAPD DNA fingerprint had 78 reliable bands with 48 polymorphic bands. The analysis of pooled ISSR-RAPD showed S. incertulas population from Kuching and Samarahan were highly related with the index 0.72. The genetic diversity among S. incertulas populations estimated were comparable and the AMOVA analysis showed higher genetic variation within population. Higher genetic variation within population may suggest the presence of different biotypes in each population. The present study is the first attempt of assessing the genetic relatedness of S. incertulas populations from northwestern Sarawak. In conclusion, the life cycle duration of S. incertulas reared under laboratory condition was estimated with an average 60 days. The adult females preferred four-month old plant for oviposition as compared to younger plants. The populations of S. incertulas from northwestern Sarawak require further validation by adding more markers to reveal the genetic diversity. Universiti Malaysia Sarawak, (UNIMAS) 2021 Thesis http://ir.unimas.my/id/eprint/34982/ http://ir.unimas.my/id/eprint/34982/4/Nur%20Najwa%20Hamsein.pdf text en validuser masters Universiti Malaysia Sarawak (UNIMAS) Faculty of Resource Science and Technology
institution	Universiti Malaysia Sarawak
collection	UNIMAS Institutional Repository
language	English
topic	Q Science (General) QK Botany QL Zoology S Agriculture (General)
spellingShingle	Q Science (General) QK Botany QL Zoology S Agriculture (General) Nur Najwa, Hamsein Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
description	The rice yellow stem borer, Scirpophaga incertulas (Walker) is an important pest of rice in Sarawak, Malaysian Borneo. For a better management of this pest, it is crucial to understand its biology and also other aspects such as the oviposition behaviour and the genetic structure which is unknown. The observation on the life cycle of S. incertulas was carried out under laboratory condition. The incubation period ranged between 7–9 days. The larval duration completed in 38–42 days. The pupal duration ranged 7–10 days. The female moths longevity was longer than the male moths with an average 4.30 ± 0.90 and 3.70 ± 0.50 days respectively. In this study, rearing of S. incertulas under laboratory condition seems to be not feasible. Mortality was the highest at larval stages hence resulted in low adult emergence. For the study on S. incertulas oviposition behaviour, several aspects of its behaviour on Sarawak rice landraces were observed in a net house experiment. A total of 180 females of S. incertulas were given access to six different rice landraces at three plant ages. The results indicated that rice plants at four-month old were strongly preferred for oviposition regardless of landraces. This is probably because of the height of the older plants as compared to the younger plants. Plants with high stature is easier to be identified by flying moths, making it preferable for the moths to rest and oviposit. The vertical distribution of egg masses on plant were varied. Oviposition on leaf surfaces showed a clear preference on the abaxial leaf surface. To analyze the genetic relatedness of S. incertulas populations, four ISSR and primers and two RAPD primers were used. The combined ISSR and RAPD DNA fingerprint had 78 reliable bands with 48 polymorphic bands. The analysis of pooled ISSR-RAPD showed S. incertulas population from Kuching and Samarahan were highly related with the index 0.72. The genetic diversity among S. incertulas populations estimated were comparable and the AMOVA analysis showed higher genetic variation within population. Higher genetic variation within population may suggest the presence of different biotypes in each population. The present study is the first attempt of assessing the genetic relatedness of S. incertulas populations from northwestern Sarawak. In conclusion, the life cycle duration of S. incertulas reared under laboratory condition was estimated with an average 60 days. The adult females preferred four-month old plant for oviposition as compared to younger plants. The populations of S. incertulas from northwestern Sarawak require further validation by adding more markers to reveal the genetic diversity.
format	Thesis
qualification_level	Master's degree
author	Nur Najwa, Hamsein
author_facet	Nur Najwa, Hamsein
author_sort	Nur Najwa, Hamsein
title	Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
title_short	Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
title_full	Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
title_fullStr	Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
title_full_unstemmed	Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak
title_sort	oviposition behaviour and genetic relatedness of scirpophaga incertulas populations from northwestern sarawak
granting_institution	Universiti Malaysia Sarawak (UNIMAS)
granting_department	Faculty of Resource Science and Technology
publishDate	2021
url	http://ir.unimas.my/id/eprint/34982/4/Nur%20Najwa%20Hamsein.pdf
_version_	1783728443294220288

Oviposition Behaviour and Genetic Relatedness of Scirpophaga incertulas Populations from Northwestern Sarawak

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