THE INFLUENCE OF CLIMATIC FACTORS ON THE INCIDENCE OF CONIESTA IGNEFUSALIS IN THE BAGAUDA AREA OF KANO STATE

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Date
1999-05
Authors
EJEH, LAWRENCE
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Abstract
The growing problem of field pests and pesticide misuse in the savanna has been of great concern among scientists and scholars. In the Nigerian Sudan savanna, where traditional agriculture is widely practised, grain pest and use of pesticides are serious constrainsts to millet production because of: i) low literacy rates of farmers in the study area ii) low income of the farmers to embark on effective chemical control, and iii) poor user understanding by the few farmers that could afford chemical control. This work related the relationship between the incidence of Coniesta-ignefusalis (a major stemborer pest of millet) and environmental factors (weather factors) in the Bagauda area in the Sudan savanna zone of Nigeria. The pest was monitored for three cropping seasons (1995 to 1997) using pheromone traps on millet fields at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) station, Baguada, Kano, Nigeria approximately on latitude 1 l°40oN and longitude 8°30'N. Pest and weather data for the three cropping seasons (1995 to 1997) were statistically analysed at three levels - the simple linear regression, the polynomial non-linear regression and the multiple linear regression. The pest population was predicted using the multiple linear regression approach. The polynomial distribution was found to be the best method for determining relationship between single or individual weather parameter- and pest incidence in the study area. Results suggested that the availability of abundance of food and absence of natural enemy has not been the only determinant in the incidence of the pests, and emphasise the importance of weather condition in assessing these effect. The incidence of the pest in the Nigerian savanna is weather dependent. Major climatic variables affecting the pest incidence in the Sudan savanna are rainfall relative humidity, radiation and temperature. The influence of rainfall was such that it correlated positively with both weekly and monthly data with r values greater than 50% in all the years of study (i.e. the higher the rainfall the higher the pest incidence). Rainfall amounts greater than 200mm were observed to hamper the pest incidence. The effect of radiation was such that it correlated negatively with the pest incidence for all the cases considered for 1995 and 1996 and 1997 monthly data with r-values greater than 50%. Radiation was, however, not statistically significant both at 5% and 1% level of significance for 1996 weekly data. Temperature influence was such that (Tavg) correlated positively with the pest for all the years of study i.e. an increase in (Tavg) leads to increase in the pest incidence (Tmin). (Tmax) is however, such that it correlated negatively with the pest incidence (i.e. an increase in (Tmax) leads to a decrease in the pest population) for 1996 data. The influence of relative humidity was such that it correlated positively with the pest incidence in all the cases for all the years of study (i.e. an increase in relative humidity leads to increase in the pest incidence). The weather variables do not work in isolation but influences the pest incidence simultaneously.
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A THESIS PRESENTED TO THE POST GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE AWARD OF BACHELOR OF SCIENCE. DEPARTMENT OF SOIL SCIENCE FACULTY OF AGRICULTURE AHMADU BELLO UNIVERSITY, ZARIA MAY, 1999
Keywords
INFLUENCE,, CLIMATIC,, FACTORS,, INCIDENCE,, CONIESTA IGNEFUSALIS,, BAGAUDA,, AREA,, KANO STATE.
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