SYNERGISM OF ORGANOPHOSPHATES IN MUSCA DOMESTICA AND CHRYSOMYA PUTORIA

Abstract

A series of symmetrical trisubstituted phosphorus compounds was tested as synergists for malathion and certain other organophosphorus insecticides against resistant and normal strains of Chrysomya putoria and Musca domestica. All the compounds synergised the insecticides more effectively against resistant than normal strains. This was especially true with malathion, notably with the C. putoria strain the resistance of which is highly specific for malathion. A 5: 1 mixture of the best synergists virtually abolished its resistance. Among the “synergists” tested, the two best were common to the C. putoria and the two different resistant strains of M. domestica; these two synergists were also outstanding against Culex tarsalis larvae, as reported by other authors. In addition to the synergistic action on malathion, the better compounds were also effective in reducing resistance to other phosphorus insecticides (Dicapthon, parathion, coumaphos) though not quite so effectively. It is concluded that their action is not entirely specific for suppressing carboxyesterase detoxication. Zusammenfassung SYNERGISMUS VON ORGANOPHOSPHATEN BEI MUSCA DOMESTICA UND CHRYSOMYA PUTORIA Eine Reihe symmetrisch dreifach substituierter Phosphorverbindungen wurde als Synergisten für Malathion und gewisse andere Organophosphat‐Insektizide gegenüber resistenten und normalen Stämmen von Chrysomya putoria und Musca domestica geprüft. Alle diese Verbindungen verstärkten die Insektizide gegen resistente Stämme wirkungsvoller als gegen normale. Das galt besonders für Malathion, vor allem bei dem C. putoria‐Stamm, dessen Resistenz gegenüber Malathion hoch spezifisch ist. Ein 5: 1‐Gemisch der besten Synergisten hob seine Resistenz praktisch auf. Unter den geprüften “Synergisten” waren die zwei besten C. putoria und den beiden verschiedenen resistenten Stämmen von M. domestica gemeinsam; diese beiden Synergisten wirkten auch gegenüber Culex tarsalis‐Larven ausgezeichnet, wie andere Autoren berichteten. Neben der synergistischen Wirksamkeit für Malathion reduzierten die besseren Verbindungen auch die Resistenz anderer Phosphor‐Insektizide (Dicapthon, Parathion, Coumaphos), wenn auch nicht ganz so vollkommen. Es wird geschlossen, daß ihre Wirkungsweise für die Unterdrückung der Carboxyesterase‐Entgiftung nicht ganz spezifisch ist.

THE MECHANISM OF MALATHION‐RESISTANCE IN THE BLOWFLY CHRYSOMYA PUTORIA

“…Certain organophosphorus compounds are known to synergise malathion, especially in resistant strains, apparently by suppressing enzymic degradation. The effects of some selected synergists on malathion-resistance in Chrysomya putoria were investigated by Bell & Busvine (1967) and it was shown that in some cases resistance could be almost completely overcome. Therefore it seemed desirable to study the effects of the more effective of these compounds on in vitro metabolism of malathion by larval fat bodies.…”

The tropical African latrine blowfly, Chrysomya putoria (Wiedemann)

“…1973. There is little comparable information on the biology of C.pirtorim, other than incidental observations made during studies in insecticide resistance and control (Bell & Busvine, 1967;Busvine erul., 1963;Conway. 1977;Gratz, 1961;Townsend & Busvine, 1969) and some recent findings from South America concerning reproduction and behaviour (Avancini & Prado.…”

Laboratory selection of greenhouse whitefly for resistance to malathion

“…The decrease in resistance to methomyl suggests that malathion and methomyl resistance are unconnected and may have evolved independently in the P-strain. DEF synergized malathion not only by inhibiting carboxylesterase in Culex tarsalis (Plapp et aL, 1963), but also through its broad action on a wide range of esterases (Bell & Busvine, 1967;Georghiou et aL, 1975). This suggests that malathion and resmethrin resistance are related.…”

“…This supports the suggestion that esterases are involved in the mechanism of malathion resistance in whiteflies. DEF synergized malathion not only by inhibiting carboxylesterase in Culex tarsalis (Plapp et aL, 1963), but also through its broad action on a wide range of esterases (Bell & Busvine, 1967;Georghiou et aL, 1975). Involvement of esterases in pyrethroid detoxification was demonstrated by Jao & Casida (1974).…”