Seasonal activity of the apple european red mite, Panonychus ulmi koch (Acari: Tetranychidae)
2012
Bhardwaj, Sushma | Sharma, Sangita
Correlation and regression studies were carried out to determine the effect of environmental factors on the population dynamics of Panonychus ulmi (Koch) on apple during 2008–2009 at Regional Horticultural Research Station, Mashobra, Shimla. Studies on the seasonal activity revealed that overwintered eggs began to hatch in the last week of March. The summer eggs were recorded for the first time in the second and third week of April. The increasing trend in motile and egg count was recorded from first week of July and reached a peak in first week of September during 2008. Whereas, during 2009, the increasing trend in mite and egg population was recorded from the first week of August and reached to maximum by the second week of September. Thereafter, continuous decline was recorded and it reached to a zero by December. The correlation coefficient (r) showed highly positive and significant correlation with minimum temperature while it was non-significant but positive with maximum temperature. Positive and significant correlation existed between mite population and relative humidity and rainfall.
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