Field susceptibility of the cocoa mirid, Sahlbergella singularis haglund (heteroptera) to some new insecticides

Abstract

AbstractTwo groups of insecticides were screened against the cacao mirid, S. singularis in small‐scale field trials from September 1969 to January 1972. In first group 0.05% promecarb, 0.04% phosphamidon and 0.02% monocrotophos were equally effective and superior to 0.05% mecarbam in the three days after spraying but 0.05% promecarb was most toxic to bugs by the seventh day. In the 0.15 to 0.2% range, all four insecticides showed similar toxicity within 3 days of spraying but only 0.15% mecarbam and 0.2% promecarb maintained control to the seventh day. For mecarbam, phosphamidon and monocrotophos, control at 0.15% was better than at 0.05, 0.04 and 0.02% respectively 7 days after spray whilst 0.2% was superior to 0.05% promecarb 2 days after spray and not afterwards.At either 0.21 or 0.33 lb/acre insecticides in the second group (pirimiphos methyl, HOE 2960, CA 6900 and dicrotophos) gave identical level of control of mirids and control at the latter dosage rate was not better than at the former. There was no significant difference between 3 and 4 oz a.i./10 gal water/200 trees in toxicity to mirids and the insecticides gave equally good control of the bugs at both dosage levels till 35th day after spray. On the basis of efficacy and safety of use, promecarb CA 6900 and pirimiphos methyl were deemed suitable for further (large scale) trials.