Acaricides organotins

The rapid rise in the industrial (catalyst in PVC and foam production), agricultural (fungicides and acaricides), and biological applications (wood, stone, and glass preservatives) of organotin(IV) compounds during the last few decades has led to their accumulation in the environment and, consequently, in biological systems. 

Resistance to organotin acaricides has been reported in several populations of spider mites. After cyhexatin and fenbutatin oxide were used for 10 to 17 years on pears and apples to control mites, populations of McDaniel spider mite (Tetranychus mcdanieli), two-spotted spider mite (T. urticae), and European red mite (Panonychus ulmi) slowly began to develop strains that were resistant to these chemicals (Croft et al. 1987). 

The latter example points out the potential of the technique as a screening method for the identification of toxic organometallic compounds, for example, in pesticide residue analysis. With an initial screening of total Sn by ICP-MS in a survey on cyhexatin (an organotin acaricide), a limited number of suspect fruit samples (three out of 72) were identified and then submitted to confirmatory analysis with a GC-MS method [85]. This approach resulted in a 30 percent reduction of the survey cost in terms of staff hours. 

Examples of organotin compounds to have found applications as agrochemicals are PhsSiiX (OH or OCOMe) (antifungicide for crops) and tricyclohexyltin hydroxide, [(PhCMe2CH2)3Sn]20, and tricyclohexylstannyl-1,2,4-triazole (acaricides). 

The organotins are a gronp of pesticides that have both acaiicide and fungicide activities. Of particnlar interest is cyhexatin (tricyclohexyl tin hydroxide), a highly specific acaricide. Later, fenbntatin-oxide was introduced and has proven to be highly effective against mites on fruits, greenhouse crops, and ornamentals. 

Dicofol resistance in spider mites, though of lesser practical importance in some agricultural systems than resistance to the organotin and organosulfur acaricides, provides a system conducive to the study of resistance dynamics. Resistance is generally manifest as a >1000-fold difference in susceptibility of resistant versus susceptible individuals to dicofol residues (12 .). ... 

Though subjectively defined, and often not intensively investigated with the necessary field and laboratory studies, the phenomenon of instability has been noted for TEPP resistance 22.), the organotin acaricides (24-26), propargite (fi.), dicofol (see below), and formetanate hydrochloride. Noteworthy contradictions regarding resistance stability exist. Welty et al. (22) found resistance to cyhexatin in Panonychus ulmi to be stable in two field... 

Major industrial uses of organotin compounds include applications of tin com-poimds in fungicides, acaricides, disinfectants, antifouling paints, stabilizers to lessen the effects of heat and light in PVC plastics, catalysts, and precursors for the formation of films of Sn02 on glass. Tributyl tin chloride and related tributyl tin (TBT) compounds have bactericidal, fimgicidal, and insecticidal properties and are... 

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