Impact of insecticides on the haemogram of Rhynocoris kumarii Ambrose and Livingstone (Hem., Reduviidae)

Abstract: The haemogram of Rhynocoris kumarii Ambrose and Livingstone comprises prohaemocytes, plasmatocytes, granular haemocytes, cystocytes and oenocytoids. The impact of five insecticides, viz. monocrotophos, dimethoate, methylparathion, quinalphos and endosulfan on the total haemocyte count (THC) and differential haemocyte counts (DHC) was studied. All of the insecticides except endosulfan initially reduced both prohaemocytes and plasmatocytes, increased the granular haemocytes, altered the percentage of cystocytes and oenocytoids and increased the total haemocyte count (THC). On the contrary, endosulfan initially increased the prohaemocytes and plasmatocytes, decreased the granular haemocytes and also the THC. The highest impact on the DHC and THC was caused by methylparathion and monocrotophos and the least impact by endosulfan. Hence, endosulfan is considered as the safest insecticide followed by dimethoate and quinalphos among these five insecticides to use with R. kumarii.