Residual efficacy of cypermethrin and pirimiphos-methyl against Sitophilus granarius (L.) and Plodia interpunctella (Hübner) on concrete surface

Abstract

Residual activity of EC formulations of two insecticides, cypermethrin (combined with the synergist piperonyl butoxide) and pirimiphos-methyl, against Sitophilus granarius (L.) adults and Plodia interpunctella (Hübner) larvae was investigated on concrete surface. The experiment was run indoors at 16-24ºC temperature and 30-60% r.h. by applying water solutions of products based on cypermethrin (48 mg AI/m2) and pirimiphos-methyl (750 mg AI/m2) to concrete surface. Insect mortality was estimated after 2, 7 and 14 days of insect exposure to treated concrete and 7 days of recovery on untreated coarse wheat meal at 24-26ºC and 55-65% r.h in the laboratory. High efficacy of cypermethrin against S. granarius adults (87-100%) and P. interpunctella larvae (84-100%) was detected after 14 days of exposure to all deposits on concrete surface. Pirimiphos-methyl achieved maximum efficacy (100%) in all treatments of S. granarius adults and P. interpunctella larvae after 2 and 14 days of exposure, regardless of deposit age. After 7 days of recovery, the efficacy of both insecticides mostly increased, especially of cypermethrin, up to around 50% after two days of exposure, up to 24-45% after seven days of exposure and up to 15% after 14 days of exposure. The results show that the EC formulations of cypermethrin and especially of pirimiphos-methyl were highly effective in controlling S. granarius adults and P. interpunctella larvae over a period of 60 days following application to concrete surface.

Sa adultima Sitophilus granarius (L.) i larvama Plodia interpunctella (Hübner) je na betonu ispitivana rezidualna efikasnost dva insekticida EC formulacije: cipermetrina (sa sinergistom piperonil butoksidom) i pirimifos-metila. Eksperiment je izveden u zatvorenoj prostoriji na temperaturi 16-24ºC i 30-60% r.v.v., nanošenjem vodenih rastvora preparata na bazi cipermetrina (48 mg AI/m2) i pirimifos-metila (750 mg AI/m2) na beton. Smrtnost je utvrđivana posle 2, 7 i 14 dana izlaganja test insekata na depozitima starosti 0, 7, 14, 30 i 60 dana i 7 dana oporavka na netretiranoj pšenici u laboratorijskim uslovima, na temperaturi 24-26ºC i 55-65% r.v.v. Visoka efikasnost cipermetrina za adulte S. granarius (87-100%) i larve P. interpunctella (84-100%) utvrđena je posle 14 dana izlaganja na svim depozitima na tretiranom betonu. Pirimifos-metil je, bez obzira na starost depozita, u svim ispitivanim varijantama bio maksimalno efikasan (100%) za adulte S. granarius i larve P. interpunctella, posle 2, odnosno 14 dana izlaganja. Posle 7 dana oporavka efikasnost oba insekticida se najčešće povećavala, a posebno cipermetrina, do oko 50% posle dva dana izlaganja, do 24-45% posle sedam dana izlaganja i do 15% posle 14 dana izlaganja. Dobijeni rezultati pokazuju da EC formulacije cipermetrina i, posebno, pirimifos-metila ispoljavaju visoku efikasnost u suzbijanju adulta S. granarius i larvi P. interpunctella tokom 60 dana od nanošenja na beton.