Resistance management, critical

Excellent progress has been made in the understanding of the cause, nature, genetics, mechanism and solutions of herbicide-resistant weeds since the first triazine-resistant common groundsel was reported more than 35 years ago. Resistance management programs have been extremely successful in controlling most weeds that have developed resistance to the triazine herbicides. However, research is critical to better understand the rapid increase and spread of many new weed biotypes resistant to several classes of herbicides. 

After many years of relative passivity in the face of resistance, a more aggressive concept of "resistance management" has developed considerable momentum in the last decade as it has become clear that new pesticides will not be readily available to replace those lost to resistance. This approach is reviewed elsewhere much more fully than is possible here (21,23-26). There are several critical areas of resistance management where a knowledge of pest biochemistry and physiology is essential ... 

The mainstay of medical treatment is fluid restriction, but this may not be appropriate in the surgical and critical care patient population. Severe (<120 mmol-L-l) or symptomatic hyponatraemia (mental status changes, seizure) requires more aggressive therapy to reduce cerebral oedema. Infusion of hypertonic saline to increase plasma sodium concentrations to 120-125 mmol L-1 alleviates symptoms. Adjunct therapy with demeclocycline (600 mg-day-1) may assist management in resistant SIADH. Demeclocycline is a tetracycline antibiotic which inhibits the actions of ADH at the renal tubules. 

Modem herbicides have revolutionized the efficient production of most agricultural crops, and they will continue to be essential in feeding our present and future population. Atrazine and the triazine herbicides are critical in the management of weeds resistant to alternative herbicides. We must continue to develop management strategies for triazines and other herbicides as essential tools for weed control in agricultural production. 

These mediators can produce a number of effects including bronchiolar constriction, capillary dilatation, or urticaria (i.e., hives). In severe episodes of type I reactions a life-threatening anaphylaxis can develop in humans due to extreme bronchoconstriction and precipitate hypotension. Epinephrine is the principal drug used in the acute management of these critical effects since it achieves (1) an elevated blood pressure via activation of alpha receptors in peripheral resistance blood vessels and (2) relaxation of bronchiolar smooth muscle via activation of (32 receptors in the lung. Relief from the dermatological problem (i.e., hives) is also achieved via vasoconstriction of capillaries in the skin that reduce permeability, and, hence, fluid accumulation. Penicillin is a classic example of a drug that can cause a type I reaction. 

Eckardt KU. Anaenua of critical illness— implications for understanding and treating rHuEPO resistance. Nephrol Dial Transplant 2002 17 48-55. Rudis M, Jacobi J, Hassan E, Dasta J. Managing anemia in the critically ill patient. Pharmacotherapy 2004 24 229-247. 

The editors began with the conviction that resistance can be managed. The papers and discussions at the symposium reinforced this conviction. We believe that this volume will do the same for its readers, especially those in the chemical community, that it will also provide them with the latest findings in a dynamic field of critical importance ... 

From the standpoint of managing resistance to dicofol in spider mite pests of New York apple orchards, our findings for T. urticae are positive. Most populations had fewer than 10% resistant mites, and our laboratory data indicated that the resistant genotypes of T. urticae are substantially less fit than susceptible ones. Field studies of the critical frequency for dicofol resistance (i.e., the frequency at which resistance results in appreciable reductions in control) indicate that frequencies of resistance must be >20% to impair performance of dicofol treatments. Therefore, dicofol treatments would be expected to provide acceptable control of 9-12 of the 15 T, urticae populations we sampled. However, P. ulmi is the dominant spider mite pest of apple in western New York and, as we have demonstrated, the species most likely to exhibit resistance to dicofol. 

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