Mite control, avermectins

Avermectins and Ivermectin. The avermectias are pentacycHc lactones isolated from fermentation products of Streptomjces avermitilis and ivermectin is a semisynthetic chemical, 22,23-dihydroavermectia (46). Ivermectin is effective in very low doses for the control of red spider mites on deciduous fmits, in baits for the control of imported fire ants, and as a parasiticide for Onchocerca volvulus in humans and for catde gmbs. These insecticides appear to function as agonists for the neuroinhibitory transmitter y-aminobutyric acid (GABA) (see Antiparasitic agents, avermectins). 

Avermectin (Avid ) is a prodnct nsed in commercial crop production. The chemical is produced by bacteria and is used to control leafminers and spider mites. Sodium aluminofluoride or cryolite (Kryocide ) has been used for many years in organic crop production. This product is used to control several types of insects on a wide variety of crops. 

Two examples of the remarkable potency of avermectin Bj are its LD9Q of 0.02 to 0.03 ppm against the two-spotted spider mite, Tetranychus urticae, when applied to bean plants as a foliar spray and its control of the red imported fire ant, Solenopsis invicta, when applied as a bait at a level as low as 25 to 50 mg per acre (19). 

The microorganism was classified as a new species of actinomycete. Streptomyces avermitilis. Its anthelmintic activity was shown to reside in 8 closely related macrocyclic lactones, named avermectins, which were also found to possess activity against free-living and parasitic arthropods. One of the natural components, avermectin is now being evaluated as a pesticide for the control of mites of citrus and cotton crops and control of the Red Imported Fire Ant. A chemical derivative, 22,23-dihydroavermectin or ivermectin, has been developed as an antiparasitic agent. It is being marketed for use in cattle, horses and sheep and is expected to become available for swine and dogs. 

Results from these laboratory studies demonstrated that avermectin Bj had high toxicity for the twospotted spider mite (Tetranychus urticae) on bean plants. When applied in solution directly onto adult and nymphal spider mite populations on foliage, avermectin Bj was shown to be 50-200 times as potent as commercially available acaricides, with an LC q of 0.02-0.03 ppm. Additional tests on foliage with insects in the order Lepidoptera, Coleoptera, Homoptera, Orthoptera, Diptera, Isoptera and Hymenoptera confirmed the broad spectrum activity and potency of the avermectin family of compounds and avermectin Bj in particular. Table II provides LC q values for avermectin Bj for the control of larval forms of several of these insects in foliar residue assays (18). 

The high cost of developing compounds with limited markets has reversed the trend to narrower spectrum agents. The reversal began with the pyrethroids and has continued with the discovery, from fermentation sources, of the avermectins. In addition to their anthelmintic properties (see Section 1.08.2), a semisynthetic derivative, ivermectin (16), is in use in the control of lice, mites and warbleflies. Activity against Boophilus ticks, including all... 

Abamectin is an insecticide/acaricide that contains a mixture of avermectin Bja (>80%) and avermectin Bjb (<20%) as active ingredients. Avermectins, which are macrocyclic lactones, are derived from the actinomycete, Streptomyces avermitilis (soil microorganism). It is used to control insect and mite pests of a wide range of agronomic, fruit, vegetable, and ornamental crops. It is also used by home owners for control of fire ants. It has an oral LD50 in rats of 300 mg/kg. 

Milbemectin, a synthetic avermectin-type product, is an insecticide/acaricide. It contains a mixture of milbemectin A3 and milbemectin A4. It is used for control of citrus red mites, pink citrus rust mites, and Kanzawa spider mites on citrus, tea, and others. Its oral LD50 in rats is 762 mg/kg. 

Avermectin (Ivermectin) (Doramectin) (Abamectin) (Eprinomectin) Mites, lice, Horn fly. Warble-fly larvae Solution (pour on) Parenteral solution (S.C. injection) Controlled-release ruminal bolus (ivermectin)... 

Control Spray fruit trees with dormant oil to kill overwintering eggs in garden or greenhouse rinse plants with water and mist daily to suppress reproduction of mites release predatory mites Metaseiulus occiden-talis on fruit trees, Phytoseiulus persimilis or similar species on vegetables, strawberries, and flowers spray insecticidal soap, pyrethrin, or neem as a last resort, spray infested plants with avermectins. 

Protection Offered Avermectins arc registered to control spider mites and leafminers on flowers and ornamental foliage crops. 7 hey are also available as a fire ant bait, but other garden uses await federal approval. 

How to Use You can buy avermectins in spray form to control leafminers and spider mites. Spray both upper and lower surfaces of leaves thoroughh to ensure good coverage. To control fire ants, broadcast the poison bait or apply it to individual ant mounds, according to label instructions. Placing the bait in... 

Concurrent with the development of ivermectin for the veterinary market, Merck began to report field studies demonstrating the insecticidal potential of ivermectin s parent structure, avermectin B1 (abamectin) (6). Avermectin B1 is currently under development for control of phytophagous mites and certain insect species such as leaf miners in crops and omamentds (g). 

In this chapter mention has been made of marketable products such as the avermectins for mite, insect, and animal parasite control and Bacillus thuringiensis for control of various insect species, which are triumphs of the application of fermentation and microbiological applied science. Many new products are currently under development in this area. In addition, amino acids and other chemical intermediates, particularly those with chiral centers, now are produced economically with such techniques. 

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