Aphids are very serious pest in
greenhouses and field in many
countries. The toxicity of two
insecticides with different mode
of action and three petroleum
ether plant extracts were tested
against two aphid species; Brevicoryne brassicae L, and Aphis
craccivora koch in the laboratory
using leaf-dip bioassay. The toxicity index showed that the carbamate insecticide, primicarb has
the highest aphicidal activity.
Based on the LC50 values, primicarb was the most toxic compound with LC50S of 0.12 and
0.26 mg/L against B. brassicae
and A. craccivora, respectively.
Imidacloprid was the least toxic
compound against B. brassicae
with LC50 of 2.14 mg/L. Against
A. craccivora, henbane extract
was the least toxic compound
(LC50=19.7 mg/L.). The results
indicated that field efficiency of
primicarb and imidacloprid were
compatible with the laboratory
results. However, plant extracts
showed opposite results under
field conditions.