Effects of Application Programs on Citrus Red Mite Control and Development of Resistance to Acaricides1

Under field conditions citrus red mite ( Panonychus citri (Mc-Gregor)) populations became resistant to demeton and Tedion® (2,4,4′,5-tetrachlorodiphenyl sulfone) following 3 to 5 applications, to Kelthane®(4,4′-dichloro- alpha -(trichloromethyl)benzhydrol) after 7 to 12 treatments, to Neotran® (bis( p -chlorophenoxy) methane) as a result of 14 sprays but remained susceptible to Aramite® (2-( p-tert -butylphenoxy)-1-methylethyl 2-chloroethyl sulfite) through 19 treatments covering a period of 8 years. Alternating acaricides, combining acaricides into a single treatment, or combining acaricides with petroleum oil did not increase the possible number of applications before resistance developed. Where demeton was ineffective and mites had developed resistance to organophosphorus compounds in general, ethion applications resulted in adequate control even though laboratory tests indicated a 10-fold degree of resistance to ethion. Resistance to ovex continued for the 8 years covered by this study; but Neotran-resistant mites became susceptible again in 3 years where Neotrun treatments had been replaced by a Tedion and petroleum oil combination.