Efficiency of phosphine and combinations of phosphine with carbon dioxide against khapra beetle larvae Trogoderma granarium Everts. (Col., Dermestidae)
1989
El-Lakwah, F.A. | Wohlgemuth, R. | Khattab, M.M.
Investigations conducted in the laboratory for comparing the efficacy of phosphine with that of mixtures of the gas plus carbon dioxide against diapause larvae of Trogoderma granarium showed that addition of varying concentrations of CO2 (20, 50, 75 and 100 per cent) to fixed PH3-concentrations had a negative influence on phosphine efficacy against diapause larvae of khapra beetle at 30 degrees C for short exposure periods of 18 and 24 hours. On the other hand, it was found that for longer exposure periods of 48 and 72 hours, the addition of CO2 to phosphine induced significantly higher larval mortality than that by PH3 alone, whereby an additive effect was proved for mixtures contained PH3 + 75 per cent and 100 per cent CO2. The addition of 20 per cent and 50 per cent C 02 to PH3 at 20 degrees C did not show any increase in larval mortalities of the mixtures for exposure periods between 24-96 hours. The larval mortalities obtained for an atmosphere contained 20 and 50 per cent CO2 alone at 20 and 30 degrees C was (0-6 per cent) and (10-40 per cent), respectively, after 10 days exposure period
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