Insect resistance to insecticides

Abstract

A B S T R A C TThe past 40 years have seen insect resistance to insecticides develop fiom a scientijic curiosity to an immense practical problem that threatens man's ability to control not only the insect pests of agriculture but also the insect vectors that transmit major human and animal diseases. The spread of genes for cross and multiple resistance among insect pests has rendered most of our present insecticides obsolescent and very few novel insecticides are under development as substitutes. The most feasible strategy to maintain adequate control of insect pests is integrated pest management or I P M , in which insecticide management is a useful component. However, much of our present planning for the future of insect control is carried out in ignorance of past failures. W e must learn @om the past if we are to retain the use of chemical insecticides as a viable component of I P M .

Modulation ofAnopheles gambiaeEpsilon glutathione transferase activity by plant natural productsin vitro

“…The mosquitoes that transmit malaria best A. funestus and A. gambiae dominate in Africa. By 1984, a world survey showed that 233 species, mostly insects were resistant to DDT [31]. This study has identified Tral-1 and GG1 as natural plant compounds that inhibit the AgGSTE2 in vitro and might possibly restore sensitivity to DDT in DDT resistant species.…”

Cross-resistance in the lightbrown apple mothEpiphyas postvittana(Lepidoptera: Tortricidae)

“…It is possible that the increased detoxication of carbaryl and chlorpyrifos was linked to the higher levels of non-specific esterases and/or mixed function oxidases in the BB and selected T7 strains, although this requires testing. Resistance to these insecticides could conceivably be the result of other mechanisms, such as reduced penetration (Metcalf 1989), although this has not been examined. It is therefore not possible to completely eliminate the possibility that multiple, rather than cross-resistance is present in LBAM.…”

“…Resistance is commonly defined as a 5-fold or greater difference in LC so , whereas "tolerance" commonly refers to smaller differences in response. Cross-resistance refers to an insect population surviving applications of chemically related insecticides because of a common mechanism (Metcalf 1989). Multiple resistance is the development of different resistance mechanisms in the same insect population (Keiding 1986).…”

Resistencia de la garrapata Boophilus microplus a los ixodicidas

“…La resistencia se define como la capacidad adquirida por individuos de una población parásita que les permite sobrevivir a dosis de químicos que generalmente son letales para una población normal (Woodham y col 1983; Nari y Hansen, 1999). La resistencia cruzada (RC) es el mecanismo que utilizan especies de insectos resistentes para sobrevivir a la exposición de insecticidas relacionados químicamen-te, usando un patrón de detoxificación genérico (Metcalf 1989). La resistencia múltiple (RM) es la utilización de varios mecanismos hacia la acción de varias clases de insecticidas no relacionados químicamente (Metcalf 1989).…”

“…La resistencia cruzada (RC) es el mecanismo que utilizan especies de insectos resistentes para sobrevivir a la exposición de insecticidas relacionados químicamen-te, usando un patrón de detoxificación genérico (Metcalf 1989). La resistencia múltiple (RM) es la utilización de varios mecanismos hacia la acción de varias clases de insecticidas no relacionados químicamente (Metcalf 1989).El uso frecuente de ixodicidas ha provocado la selección de poblaciones de garrapatas resistentes (Kunz y Kemp 1994). El principal problema que enfrentan los entomólogos es la resistencia a químicos, debido a la presencia de RC y RM entre plagas de insectos, dismi-…”