To establish an insecticidal resistance surveillance program, Culex quinquefasciatus mosquitoes from São Paulo, Brazil, were colonized (PIN95 strain) and analyzed for levels of resistance. The PIN95 strain showed low levels of resistance to organophosphates [malathion (3.3-fold), fenitrothion (11.2-fold)] and a carbamate [propoxur (3.0-fold)]. We also observed an increase of 7.4 and 9.9 in alph...

Dominance has been assessed in different ways in insecticide resistance studies, based on three phenotypic traits: the insecticide concentration required to give a particular mortality (DLC), mortality at a particular insecticide dose (DML), and fitness in treated areas (DWT). We propose a general formula for estimating dominance on a scale of 0 to 1 (0 = complete recessivity and 1 = complete d...

A. W. A. BROWN It is now 21 years since DDT -resistant house flies were first discovered in northern Sweden, and since the report of Wilson and Gahan that a DDT -resistant strain could be produced by laboratory selection at Orlando. Although the resistance of the San Jose scale to lime-sulfur was detected by Melander in Washington state nearly 60 years ago, the resistance problem as we know it ...

Pest resistance to pesticides is an increasing problem because pesticides are an integral part of high-yielding production agriculture. When few products are labeled for an individual pest within a particular crop system, chemical control options are limited. Therefore, the same product(s) are used repeatedly and continual selection pressure is placed on the target pest. There are both financia...

High levels of resistance to the major categories of insecticides, ie, organophosphorus, carbamates, pyrethroids, and DDT, have been detected in the diamondback moth in Taiwan. Synergist studies have provided insufficient evidence to show significant involvement of known metabolic systems, such as microsomal oxidation, esterase hydrolysis, and glutathione conjugation in organophosphorus and car...

The use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely...

BACKGROUND Asian citrus psyllid (ACP), Diaphorina citri, is a major pest of citrus because it vectors the putative causal agent of huanglongbing disease. Insecticides are currently the basis of psyllid management programs, and the number of annual insecticide applications has increased significantly. In this paper, a series of investigations of insecticide resistance among field populations of ...

In addition to the inherent challenge, driven by curiosity and the excitement of the chase, the quest for malaria vaccines has been made more imperative over the past two decades or so by pragmatic assessment of the odds in a disease which has been with mankind for millenia. Accel­ erating spread of parasite resistance to more and more drugs, with too few new molecular structures in the pipelin...

1. Phenotypic diversity is the fuel that powers evolution. 2. Asexual organisms rely on mutation whereas sexual organisms combine mutation with recombination. 3. Few organisms provide examples of species that are both sexual and asexual, but aphids do. 4. To examine evolution on perceptible timescales requires strong evolutionary forces and, as Darwin noted, agricultural practices provide stron...