Acaricidal and Insecticidal Activity

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 

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The avermectins, a family of compounds with potent anthelmintic, insecticidal and acaricidal activity, have vividly demonstrated that fermentation products can have entirely unanticipated activities. Besides their utility in animals, they show great promise for the control of insect pests of plants. Although antibiotics have found only a limited role in the control of plant diseases, the desire to find environmentally acceptable alternatives to the chemicals currently used has prompted new research efforts to discover fermentation products for use as pesticides. 

Another incentive to this screening may have arisen from the discovery of two remarkably potent families of fermentation products with insecticidal and acaricidal activity, the milbemycins and the avermectins. Abamectin (a mixture of not less than 80% avermectin and not more than 20% avermectin is already... 

Chlorfenapyr (Phantom ), a trifluoromethyl-containing pyrrole ring insecticide, belongs to a new class of uncouplers of oxidative phosphorylation [80], The original insecticidal lead that resulted in chlorfenapyr was the fermentation product dioxapyrrolomycin, isolated from a Streptomyces strain [81], The presence of the trifluoromethyl group is essential for a broad spectrum of insecticide and acaricide activity. 

The compounds were evaluated for insecticidal and acaricidal activity against the following species cabbage looper (Trichoplusia ni [Hubner]), Mexican bean beetle (Epilachna varivestis Muls), southern armyworm (Spodootera eridania [Cram]), pea aphid (Acvrthosiphon pisum [Harris]), twospotted spider mite (Tetranvchus urticae [Koch]) and southern corn rootworm (Diabrotica undecimpunctata Howardi). 

Table I. Insecticidal and acaricidal activity of Delphinium extracts compared with MLA...

Nikkomycins are nucleoside amide antibiotics produced by Streptomyces tendae Tii 901 and are known to show antifungal, anti-insecticidal, and acaricidal activities. They are competitive inhibitors of chitin synthase. Nikkomycins are produced as a complex mixture, with nikkomycin Z (13) and nikkomycin X (14) representing the major components. ... 

Structually much more complex molecules have also been submitted to re-gioselective enzymatic hydroxylation. Two such examples have been described involving milbemycin, a sixteen-membered macrolide which exhibits broad-spectrum insecticidal and acaricidal activity, and monensin, a carboxylic polyether antibiotic193- 94l Milbemycin (Fig. 16.1-19) was thus regioselectively hydroxylated at the 13(3 position (followed eventually by a C-29 hydroxylation) to afford the 13P,29-... 

A group of more than 20 naturally occurring macro-lide antibiotics from Streptomyces hygroscopicus var. aureolacrimosus with antiparasitic, insecticidal, and acaricidal activities. Common structural features are the differently substituted, 16-membered lactone ring and a spiroketal unit. In terms of structure and activity, the M. are closely related with the avermectins. Examples of this class of compounds are M. D (C33H48O7, Mr 556.74, needles, mp. 186-188 °C), M. E (C34H52O7, Mr 572.78, amorphous) and M. (C3,H4205, Mr 494.67) . 

Streptomyces fumanus (Sveshnikova) [4]. This compound displayed broad, moderate insecticidal and acaricidal activity [5]. However, the relatively high oral toxicity on mice precluded it from development. 

Abamectin is isolated from the fermentation of Streptomyces avamitilis, a naturally occurring soil Actinomycete (Table 29.6.2). It possesses strong anthelmintic, insecticidal, and acaricidal activity [8-13]. It tvas introduced as an acaricide and insecticide by Merck Sharp Dohme Agvet (notv Syngenta Crop Protection AG) in 1985. 

T. C. Barden, G. Asato, Z. H. Ahmed, D. J. France, V. Kamesvaran, E. Parker-Jackson, S. Y. Tamura, S.-S. Tseng, B. L. Boolcwalter, New Series of Milbemycin Macrolides (LL-F28249) with Endectocidal, Insecticidal, and Acaricidal Activity, ACS Symposium Series No 504, American Chemical Society, Washington DC, pp. 227-237,1992. 

UDP-7V-acetylglucosamine (uridine diphosphate), nikkomycins act as potent competitive inhibitors of chitin synthase and exhibit potent fungicidal, insecticidal, and acaricidal activities [320]. Nikkomycin X and Z, isolated as major components, contain the hydroxypyridylhomothreonine (HPHT) moiety, the aminohexuronic acid, and a nucleoside moiety N-glycosidically linked to 4-formyl-imidazolin-2-one or a uracil base, respectively [321, 322]. 

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