Acaricides strobilurins

At present, nine different strobilurins have been introduced into the fungicide market (see Table 13.2.1 and Fig. 13.2.2 below), and one more has been announced as being developed in China (enestroburin). There is also a strobilurin commercialized in Japan as an acaricide (fiuacrypyrim). 

In the patent literature, many claims and some data can be found about insecticidal and acaricidal activities of strobilurins. Attempts to optimize insecticidal performance did not lead to a commercial product. It seems that, with strobilurins, sufficient insecticidal activity can only be obtained if the compound has very high lipophilicity and very high metabolic stability. This combination of properties gave numerous compounds with excellent insecticidal activity but also with unacceptably high acute mammalian toxicity, so that candidates were abandoned rather early in the research phase. It seems impossible to separate the tight connection between insecticidal and mammalian toxicity in this particular case. Similar problems have been reported for respiration inhibitors of Complex I [82a]. 

In contrast to insects, mites seem to be much more sensitive to strobilurins, so that the chances of finding selective strobilurin acaricides are better than in the... 

Complex III has been very successfully exploited as a target site for fungicides such as the strobilurins, fanoxadone and fenamidone [75]. However, it has only been in the last few years that insecticidal or acaricidal products have used inhibition at Complex III as a mode of action. 

Fluacrypyrim (73 2002, Titaron , Nippon Soda) [118] is the first strobilurin analogue to be marketed as an acaricide rather than a fungicide - it inhibits mitochondrial electron transport at complex III of the respiratory chain. It is active against all growth stages of spider mites and shows an acaricidal contact and... 

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