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STUDIES ON THE APHIDS DISTRIBUTION PATTERN AND THEIR NATURAL ENEMIES IN WHEAT AND MAIZE CROP

Khan, Shah Alam (2005) STUDIES ON THE APHIDS DISTRIBUTION PATTERN AND THEIR NATURAL ENEMIES IN WHEAT AND MAIZE CROP. PhD thesis, NWFP Agriculture University, Peshawar.

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Abstract

Studies were conducted on the population dynamics of the cereal aphids in wheat and maize along with population trend of predators and parasitoids associated with the cereal aphids on wheat during 2001-2004. During the first phase of the research project surveys were conducted to investigate the population trends of the various aphid species attacking the wheat crop in the province. Nine (9) sites D.I. Khan, Bannu, Kohat, Hangu, Peshawar, Charsadda, Mardan, Haripur and Abbottabad) were selected throughout the province for sample collection. Samples were collected fort nightly from January-April. Rhopalosiphum padi, Sitobion avenae and Schizaphis graminum were the three major species collected from all the nine sites. The aphids appear earlier and departed earlier in warm areas and appeared late and departed late in the colder regions with peak infestation during the 3rd week of February. The surveys for the natural enemies were conducted in Peshawar valley only and the samples of the parasitoids and major species of the Lady Bird Beetles (predators) were taken into account. Aphidius ervi, Aphidius colemani were the predominant species of the parasitoids with peak parasitism was 78%, 93%, 95% and 100 % during the month of April. Other species among the predatory coccinellids, were C. septumpunctata and Menochilus sexmaculata the major species ubiquitously present throughout the survey areas and period. Hippodemia veriagata and Bromoidus suturalis were also present through out the study area but their number was far less as compared with the other two species. Among the twenty wheat genotypes tested for resistance, only, Tatara-98 promised to be having some types of resistance to the cereal aphids. Khaniwal & Pirsabak-85 proved to be the susceptible varieties. R. padi, S. avenae and S. graminum were the major species with infestation period started from January and lasted till March/April with peak activity period in the second and third week of February. Supracide 40EC proved to be more effective against the cereal aphid in susceptible varieties with (7.8%) as compared to the resistant one (2.3%) with the yields & yield component resulted in 2508 and 2128 kg/ha. R. maidis was restricted to maize only and seldom recorded on wheat. Among the three varieties Jalal of maize was comparatively resistant while Sarhad white & Azam were susceptible. Yield and yield components of the maize varieties treated with Confidor, Kadan and Diamethoate (All in full & half doses) recorded that Confidor was the best (yield component 2895 kg/ha) as compared to other treatments (2878 and 2854 respectively). On the overall basis, R. padi, S. avenae, & S. graminum are the three major cereal aphids species with R. padi, being the most dominant one. The aphids infestation started from January and lasted till April with peak infestation in the second and third week of February Aphidius ervi, Aphidius colemani were the two predominant parasitoids while C. septumpunctata and M. sexmaculata were the predominant coccinellids. Tatara-98 proved resistant and Khaniwal a susceptible varieties and could be used as differential host for further studies. Maize variety (Jalal) proved to be resistant to the cereal aphid and Confidor proved to be the best as seed treatment.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Cereal Aphids, Wheat, Maize, Lady Bird Beetles, Aphidius Ervi, Aphidius Colemani, C. Septumpunctata, Menochilus Sexmacula, Tatara-98, Khaniwal, Pirsabak-85, R. Padi, S. Avenae, S. Graminum, Supracide 40EC, R. Maidis, Jalal, Sarhad White, Azam
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1)
ID Code:356
Deposited By:Mr Ghulam Murtaza
Deposited On:09 Aug 2006
Last Modified:04 Oct 2007 21:00

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