Susceptibility of an organophosphate resistant strain of the two-spotted spider mite (Tetranychus urticae) to mixtures of bifenazate with organophosphate and carbamate insecticides

Abstract

Bifenazate, a new and frequently used carbazate, is a pro-acaricide which needs to be activated by carboxylesterases. We evaluated the possible antagonism of organophosphate and carbamate insecticides on bifenazate toxicity in Tetranychus urticae applied in mixtures. Two organophosphate resistant strains were used (WI and MR-VL) and several organophosphate (chlorpyrifos, azinphosmethyl and phosmet) and carbamate (carbaryl and methomyl) insecticides were evaluated. Mixing chlorpyrifos with bifenazate decreased bifenazate toxicity in both tested strains. However, in the strain with a higher esterase activity, antagonism decreased after 2 days. Of all other tested chemicals, only methomyl displayed an antagonistic effect 1 day after treatment. These findings indicate that mixing organophosphate and carbamate insecticides with bifenazate may inhibit bifenazate efficacy under field conditions, especially when resistant strains are present.

The economic importance of acaricides in the control of phytophagous mites and an update on recent acaricide mode of action research

“…5f) inhibit complex III in such assays (Van Leeuwen and Lümmen, data unpublished), because bifenazate itself is probably not the active toxophore. One of the first steps in bifenazate activation might be ester-hydrolysis to the hydrazine derivative, as esterase inhibitors strongly antagonize bifenazate toxicity [48,73]. Also, it was reported that one of the principle metabolites, the diazene, was equally toxic to spider mites [67], and a combination of ester hydrolysis and oxidation to the diazene would lead to azo-derivatives after decarboxylation [48].…”

Pesticide Mixtures

“…Antagonism occurs when mixing two or more pesticides together results in reduced efficacy (based on percent mortality) compared to separate applications of each pesticide or when the combined toxicity of two materials when applied together is less than the sum of the toxicities of the materials when applied separately (Lindquist 2002). Antagonism may compromise the efficacy of insecticides and/or miticides under field conditions (Khajehali et al 2009). For example, mixing together the miticide bifenazate with the organophosphate insecticide chlorpyrifos, and carbamate insecticides carbaryl, methomyl, and oxamyl decreased the efficacy of bifenazate against the twospotted spider mite indicating the occurrence of antagonism (Van Leeuwen et al 2007;Khajehali et al 2009).…”

“…Antagonism may compromise the efficacy of insecticides and/or miticides under field conditions (Khajehali et al 2009). For example, mixing together the miticide bifenazate with the organophosphate insecticide chlorpyrifos, and carbamate insecticides carbaryl, methomyl, and oxamyl decreased the efficacy of bifenazate against the twospotted spider mite indicating the occurrence of antagonism (Van Leeuwen et al 2007;Khajehali et al 2009). However, these effects may vary depending on the insect or mite strain (or strains), physiology, and resistance mechanisms present in the population (Ahmad 2004).…”

“…Pesticide mixtures may be more effective against certain life stages including eggs, larvae, nymphs, and adults of arthropod pests than individual applications (Blümel and Gross 2001) although this may vary depending on the rates used and formulation of the pesticides mixed together (Blümel and Gross 2001). There is already wide-spread use of pesticide mixtures associated with greenhouse and nursery operations world-wide, partly because combinations of selective pesticides may be required in order to deal with the arthropod pest population complex present in the crop (Tabashnik 1989;Bynum et al 1997;Helyer 2002;Ahmad 2004;Warnock and Cloyd 2005;Cloyd 2009; Khajehali et al 2009). Typically, two pesticides are mixed together; however, it has been demonstrated that three or more pesticides may be combined into a spray solution to target different insect and/or mite pests (Cloyd 2009).…”

Bioactivity of Indigenous Medicinal Plants against the Two-Spotted Spider Mite, Tetranychus urticae

“…Controlling mites by chemicals alone is particularly risky because of the ability of mites to become resistant to a wide range of pesticides especially when exposed to intensive selection pressures by the application of pesticides that encourage the evolution of acaricide resistance in T. urticae that consequently lead to outbreaks of T. urticae (Funayama, 2015). Resistance of T. urticae populations to organophosphates, carbamates, tetradifon, fenbutatin oxide and other acaricides is widely reported (Tsagkarakou et al, 2002;Khajehali et al, 2009). The degree of resistance to many established acaricides has resulted in a demand for new acaricides as plant derived materials with novel modes of action (Khater, 2012;George et al, 2014).…”