Insects metabolism

Pyrethroids have low oral toxicity to mammals, and in general their insect (topical) to mammal (oral) toxicity ratio is much higher than that of the other major classes of insecticides [25]. As the reason, at least the following mechanisms are conceivable (1) negative temperature dependence - differences in body temperature between insects and mammals makes the insect nerves much more sensitive, (2) metabolic rate - insects metabolize the insecticide more slowly than mammals, and the metabolizing enzyme systems are different, and (3) differences in body size - insects will have less chance to metabolize the insecticides before reaching the target site [26]. 

Insect metabolic pathways, compounds affecting, 14 345 Insect pheromones, 14 346 Insect repellents, 14 345 Insect-resist agents, for wool treatment, 26 403-404... 

An impressive list of degradative studies has been performed with Stauffer-s R-20458 including metabolism by eight insect species (15, 16), rats (15, 17), steers (18, 19), mice (20) and mammalian enzymes (15, 20, 21). It is evident that most published investigations have concentrated on metabolism by mammals and insects. Insect metabolism of R-20458 has been reviewed (22) and a summary of nonaquatic metabolism is given in Table V. Several additional hydroxylated metabolites were identified by Hoffman et al. (17) from rats. 

The rationale for design of proallatocidins related to chromenic structure of precocenes is discussed. Stabilization against environmental conditions and insect metabolic pathways, as well as modification of transport properties, sire some of the leads followed for the synthesis of more powerful insect growth regulators of this type. Some aspects of the chemistry of 3,4-epo-xyprecocenes are also examined. 

Dauterman, W.C., Insect metabolism Extra microsomal. In Comprehensive insect physiology and physiology, Kerkut, G.A. and Gilbert, L.I., Eds., Vol. 12, New York Pergamon Press, 1985, p. 713. 

Yang, R.S.H., Enzymatic conjugation and insect metabolism, In Insecticide biochemistry and physiology, Wilkinson, C.F., Ed., New York Plenum Press, 1976, p. 177. 

Few studies have focused on the effect of viral inactivation by insect metabolism. One study investigated the infectivity of Helicoverpa punctigera NPV through the gut of a predator insect [7], Active viral inclusion bodies were collected from the excreta of the predatory, Nabis tasmanicus Remame up to 4 days after with no loss of vims activity. Similarly, Bartzokas et al. [5] studied the effect of formaldehyde fumigation on VACV infected cockroaches to determine the limits of survivability. The study found VACV ingested before formaldehyde fumigation remains viable inside the cockroaches gut and active vims may be excreted up to 5 days later. 

Insects generally are able to synthesize alkaloids themselves or take them from feed. Alkaloids play an important role in insect metabolism, behavior, protection mechanisms, and species diversification. Many pyrrolizidine alkaloid-adapted insects convert host plant pyrrolizidine alkaloids into insect pyrrolizidine alkaloids. In this operation, the acid component of plant alkaloid is replaced by 2-hydroxy acids of insect origin. This seems to be an effect of physiological adaptation and evolutionary changes in the muton. Insect pyrrolizidine alkaloids can be precursors of insect pheromone hydroxydanaidal in many species. 

Many insects metabolize terpenes they have received with their plant food to growth hormones and pheromones. Pheromones are luring and signal compounds (sociohormones) that insects and other organisms excrete in order to communicate with others like them, e.g. to warn (alarm pheromones), to mark food resources and their location (trace pheromones), as well of assembly places (aggregation pheromones) and to attract sexual partners for copulation (sexual pheromones). Harmless to the environment, pheromones may replace conventional insecticides to trap harmful and damaging insects such as bark beetles. 

Hoi KK, Daborn PJ, Battlay P, Robin C, Batterham P, O Hair RAJ, Donald WA (2014) Disseeting the insect metabolic machinery using twin ion mass spectrometry a single P450 enzyme metabolizing the insecticide imidacloprid in vivo. Anal Chem 86 3525-3532... 

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