Insecticidal spectra

Even within the lepidopteran pathotype, large differences in the insecticidal spectra of B.t. toxins exist. For example, screening of a large collection of B.t. strains has lead to the identification of strains highly toxic to Soodoptera littoralis, an insect which is insensitive to most commonly known B.t. strains. 

Acetamiprid is a neonicotinoid insecticide with outstanding systemic activities and a broad insecticidal spectrum. Acetamiprid controls diverse soil and foliar insect pests infesting cotton, sugar beet, vegetables, fruits and other major food crops by both contact and stomach action... 

After the introduction of diflubenzuron (7,) many authors published laboratory and field studies on its insecticidal spectrum. These studies cannot be discussed in the context of the present paper. 

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. 

On the basis of insecticidal spectrum and size of the toxic polypeptide fragment, we presently defined 3 types of lepidopteran-active B.t. toxins. 

In a random set of 28 B.t. strains tested with monoclonal antibodies specific for type 3 toxin, only 8 showed positive reaction. In bioassay only the same 8 strains, and only these, exhibited toxicity to S. littoralis. Thus a perfect correlation exists between the antigenic structure of B.t. toxins and their insecticidal spectrum. 

Recently, chemical modifications have been carried out with the aim of increasing its insecticidal spectrum, residual activities, and chemical stability. Ivermectin, doramectin, emamectin, eprinomectin, and selamectin have been developed, and KAV-218 has been under development (Fig. 35). 

Table II shows the insecticidal activity of flubendiamide against major insect and acarina species. Flubendiamide provided high activity on all lepidopterous insect pests, and its ECjq values were between 0.004 and 0.58 mg a.i./L. However, flubendiamide did not show activity against other insect species. Thus, the insecticidal spectrum of flubendiamide is expected to be broad among lepidoptera pests in agriculture. Against the resistant strain of diamondback moth, flubendiamide provided the same level of activity as against the susceptible strain. This result indicates that flubendiamide will be useful for insecticide resistance management (IRM) programs.

Flubendiamide represents a novel class of insecticide having a unique chemical structure, and provides a new mode of action, which acts as a RyR modulator. This activity is highly selective to insect RyR, and no cross-resistance to existing insecticides is observed. Flubendiamide will also be very suitable for Insecticide Resistant Management. Furthermore, flubendiamide shows a broad insecticidal spectrum against lepidopterous insect pests, excellent efficacy in field evaluations, and excellent safety against various beneficial arthropods and natural enemies. It will be suitable for 1PM programs. 

In 1981 when juvenoid research was started at Sumitomo Chemical, insecticide research was focused mainly on pyrethroids that act quickly on insects and have a wide insecticidal spectrum. However, the appearance of resistant insects owing... 

Table 31.1 Insecticidal spectrum of flubendiamide on major insect pests in agriculture [13].

DT has a wide insecticidal spectrum and low toxicity, however, it is released completely within 1 day from the conventional formulation because of its high water solubility, which causes leaching, run-off and the outflow of DT to underground and neighboring areas, so bioavailability to rice plants wiU be reduced, consequently decreasing the eflicacy on pests. So, release control of the active ingredients is necessary for formulations containing DT which are applied to the rice paddy field, which is the main focus for Japanese pesticides. 

Head, G., M. Pleau, S. Sivausupramanian, et. al. (2001) Insecticidal Spectrum of Activity for Cry3Bb Protein in vitro Lab Project Number C3NTO. Unpublished study prepared by Monsanto Company. 12 p. 

Haloisoxazolylureas have acardicidal and insecticidal properties 76JAP(K)7659858 and isoxazoles with a phosphorothiolate functionality are broad spectrum insecticides <80USP4212861, 78USP4104375, 78JAP(K)7825566>. 

Basically growth hormones alter the normal growth of some insect species. The juvenile growth hormone worked effectively to kill some insects in the laboratory, but when applied in the field for pest control, the hormone was not effective. Its problems centered on its high cost, rapid rate of breakdown after application, and its broad spectrum effects. For example, the hormone was found to kill beneficial species as well as pest species, much like insecticides. Thus far, it has not proven to be a useful technology for pest control (42). 

Bowman MC, Schechter MS, Carter RL. 1965. Behavior of chlorinated insecticides in a broad spectrum of soil types. J Agric Food Chem 13 360-365. 

Neonicotinoids are potent broad-spectrum insecticides that exhibit contact, stomach and systemic activity. Acetamiprid, imidacloprid, nitenpyram, thiamethoxam and thiacloprid are representatives of the neonicotinoid insecticides (Figure 1). The mechanism of action is similar to that of nicotine, acting on the central nervous system causing irreversible blocking of postsynaptic nicotinic acetylcholine receptors (nAChR). Neonicotinoid insecticides are often categorized as antagonists of the... 

Cyfluthrin is a broad-spectrum pyrethroid insecticide which provides general insect control in agricultural crops, in food-handling establishments, in the garden, and in/around the home. 

Effects of Sesquiterpene Lactones on Seed Germination. Sesquiterpene lactones are common constituents of the Asteraceae but are also found in other angiosperm families and in certain liverworts (31,32). These highly bitter substances exhibit a wide spectrum of biological activities (J 3) which include cytotoxicity, anti-tumor, anti-microbial, insecticidal (34) and molluscicidal (35) properties. Furthermore, they are known causes for livestock poisoning and contact dermatitis in humans (33). Structure-activity relationship studies on sesquiterpene lactones have demonstrated that biological activity frequently depend on the presence of the cr... 

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