Effects Of Neonicotinoid Insecticidesand Irrigation On Number Of Cotton Aphids, Aphis Gossypii Glover (Hemiptera:Aphididae) And Fungus-Infected Aphids

Abstract

Experiments with the neonicotinoid insecticides, acetamiprid and thiamethoxam, were carried out at the Edisto REC., Clemson University, SC., USA. Cotton variety DP 458 BR was planted in plots of 12 rows x 15 m in both a dryland field and under irrigation on 6 and 7 May 2002, respectively. The experiment was arranged in a split-split plot design with four replications. There were 5 insecticide treatments which were based on cotton aphid infestation levels in cotton (AIL) at each location: (1) thiamethoxam (0.05 kg a.i./ha) for aphid-free plots, thial, (2) thiamethoxam (0.05 kg a.i./ha) applied..when 30% of plants were infested, thia2, (3) acetamiprid (0.05 kg a.i./ha) applied when 30% of plants were infested, ace, (4) thiamethoxam (0.05 kg a.i./ha) when 90% of plants were infested, thia3, and (5) untreated. Applications of insecticide were made as follows: treatments no. 1, 2, and 3 on 25 June, all treatments on I July, treatment no. 1 on 11 July 2002. Karate® was applied on 19 June 2002 and it was sprayed again on 16 July and 18 July 2002 to control bollworms.. There were significant differences in number aphids among location and insecticides treatment. Infection levels in aphid population by N. fresenii were significant different among insecticides treatments