Abstract
Investigations on the biology of Gurdaspur borer of sugarcane, Acigona ste-Welts (Hampson), carried out in the field cages under semi-natural conditions, in-dicated that the incubation period occupied, on an average, 5.93 days and the hatching percentage of eggs was 75.32%. The larval and pupal stages occupied, on an average, 22 and 8.53 days, respectively. The life span of adult male and female was, on an average 2.07 and 2.76 days, respectively. The duration of copulation var-ied from 10 to 60 minutes. The total number of eggs laid by a female ranged from 2 to 69. The sex ratio was found to be 1:2.
A week after application, Dieldrin, Heptachlor, Thiodan and Methyl Parathionj(applied with irrigation water to the freshly harvested sugarcane field) gave 54.64, 58.63, 46.34 and 52.08% larval mortality, respectively as against 36,18% mortality where kerosene oil was applied.
INTRODUCTION
Sugarcane is attacked by a number of insect pests of which sugarcane borers are very important. The Acigona steniellus which, 3 to 4 decades back, used to occur in Gurdaspur District, India, has now spread in many districts of Punjab. The attack of this pest occurs at a stage when the crop is pretty grown up and it becomes very difficult to control by the application of insecticides. Delayed crushing in mill zones and ratoon-ing practice make the condition even more conducive for continuous increase in the spread of this insect pest in the areas of its non-occurrence. Studies on the biology and control of this insect pest carried out in past (Younas & Hussain, 1973 and lrshad el al., 1982) indicate that very little work has been done in Pakistan.
In the present project, an attempt has been made to carry out investigations on the biology and control of this important pest of sugarcane.
MATERIALS AND METHODS
Acigona steniellus (Hampson) larvae were collected from the infested sugarcane fields and reared in the field cages (5 x 5 feet) during the period from July to Octo-ber. The emerging adults were allowed to pair in the cages. The potted sugarcane plants where fertile females laid eggs were tagged showing the date of egg laying. The pots were placed in separate cages for the study of eggs, larval and pupal stages. Ob-servations on the emergence of moths from the pupae were recorded once each during day as well as night.
