Narrow-spectrum insecticides

FIGURE 18-20 Carbaryl and aldicarb are examples of narrow-spectrum insecticides that target specific species of pests. 

Broad-spectrum Insecticides, those of the organophos-phate family, are able to attack a wide range of pests. Examples of broad-spectrum insecticides are malathion and parathion. Narrow-spectrum insecticides are of the carbamate type, such as carbaryl and aldicarb, and target only specific pests. 

ACARICIDE. A substance, natural or synthetic, used to destroy or control infestations of the animals making up Arachnida, Acarina, mainly miles and ticks, some forms of which are very injurious to both plants and livestock, including poultry. There are numerous substances that are effective both as acaricides and insecticides others of a narrower spectrum are strictly acaricides. See also Inscctieide and Insecticide and Pesticide Technology. 

Commercial preparations of B.t.. obtained through conventional fermentation techniques, have been used for more than two decades as biological insecticides (I). They exhibit desirable properties such as high insect toxicity and environmental safety. B.t. does not affect non-target insects and is completely nontoxic to vertebrates. Nevertheless its use has been limited due to high production costs, limited stability in field conditions and a too narrow insecticidal spectrum. The insecticidal activity of B.t. relies in the crystalline inclusions which are produced upon sporulation. The crystals contain insecticidal proteins, delta-endotoxins, which affect the midgut epithelium of sensitive insects. The exact mechanism of their toxic activity is still unknown. 

Bt used in spray-on formulations is, perhaps, the most successful biopesticide. Reasons for Bt s success include ease of handling and a very high specific activity against sensitive insects. For example, a Bt insecticidal protein called CrylAc has a LCjq on Heliothis virescens neonate larvae as low as 0.07 ppm [10]. However, most individual Bt insecticidal proteins have a narrow activity spectrum. As mentioned, CrylAc is very active against H. virescens, while another Bt toxin called CrylCa is not. CrylCa is active against Spodoptera exigua, but CrylAc is not. This is perhaps... 

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