Some Insecticide Studies On The Rice Stem Borer

ABSTRACT

Insecticide bio as 3 ays were carried out on JD. thoracica

(a) adults by topical application of 1 pi drop of toxicant on their

nota; and Ob) eggs by dipping them into insecticidal solutions for

30 min. LC50 values obtained from the tests on the adults were:

Gamma BHC, 26.4Ctog/l; Pirimiphos methyl (PP511) 28.00 mg/l; Serin,

67.00 mg/l and Malathion, 580.00 mg/l. Values obtained from the

eggs tests were: PP511, 1.30 mg/l; Sevin, 5.30 mg/l; gamma BHC,

18.30 mg/l andMalathion, 83.00 mg/l.

A field trial ms carried out to assess the efficacies of PP51

gamma BHC, Sevin, Basudin (Diazinon) and Bidrin in controlling

Biopsid borer infestation in a rice farm on the Accra Plains. Spra;

applications were made of 0 .04$ active ingredient solutions of the

insecticides at 5, 8, and 11 weeks after transplanting rice variety

All the insecticides r e du c ed the- h o rer infestation compared to

the control plots at the pre-heading stage of the rice plants. Gant

M C and Bidrin treatments reduced the borer infestation more than tl:

ofcha:insecticides after the second spray application. Stem borer

infestation during the fading period was low in all the experiment

plots and yields from the treated plots were not different from the

control. Borer-induced tillering in the rice may have compensated

for the effect of borer infestation on yield.

iii

The rate of penetration of 14C-PP511 into the abdominal

cuticle of B. thoracica adult f©sales was determined by topical

application of 0.01 jiCi (0.693 pgr) of the insecticide in

cyclohexane solvent . The maximum rate of penetration, 3 »1$/min

(l86$/h) oecured 1 1 ,5 min after application when 28^ of the

applied dose had penetrated the insect’s cuticle. Toxic effects

of the insecticide became evident about 60 min after application

and became acute thereafter.