Effect of aphid infestation on photosynthesis,growth and yield of Brassica carinata A. Braun

Brevicoryne brassicae l. and lipahis eyrsimi k. are the important insect pests of brassica crops in southern punjab,pakistan. to evaluate their damage to brassica carinata a. braun,the photosynthesis,yield and yield parameters of two varieties under three levels of aphid infestation were measured. low aphid infestation significantly increased photosynthetic factors except for transpiration rate. similarly lower aphid populations increased plant and pod length,pods per plant,grains per pod,pod weight,thousand seed weight and yield per hectare. in aphid protected treatment,ucd carinata yielded 1520 kg/ha. and b. carinata yielded 1291 kg/ha. the interaction of variety and insecticide was non significant among the photosynthetic factors but significant for yield/ha. losses in yield due to aphids observed in high and moderate infestations (one spray of immidacloprid) were 41.57,50.18 and 16.29,22.49 %,respectively. the single application of insecticide was not able to return all yield losses due to aphids but it helped to recover more than 28 % losses. copyright 2015 zoological society of pakistan.