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An experiment was conducted in the Department of Entomology, College of
Agriculture, Vellayani to find the effectiveness of plant products and sterile insect
technique to contain red palm weevil in coconut. As a part of the experiment,
survey was conducted 111 the red palm weevil infested tracts of
Thiruvananthapuram district between June 2001- February 2002 to find out the
extent of damage caused by red palm weevil.
The data collected during the survey revealed that, the infestation of red
palm weevil was highest in coastal area than that in inland areas; The percentage
infestation was higher during June and less during February months. Also the
infestation was higher in palms upto 7 years old.
The results on the study of the effect of plant products to contain red palm
weevil showed that apple extract of Anacardium occidentale 10% was the best
treatment which caused highest mortality of red palm weevil. Also leaf extract of
Thevetia neriifolia , seed oil of A. indica and seed oil of Samadera indica had
shown considerable repellency of red palm weevil under laboratory conditions.
In the case of sterile insect technique, gamma radiation at 1.5 Krad was
found to be the best treatment as it caused considerable sterility as well as higher
longevity of irradiated insects. The irradiated insects should be exposed to 6
virgin females for the duration of 12 days before releasing in the field to nullify
the effect of initial fertility of unaffected sperms in the irradiated insects. The
studies also revealed that there were repeated mating in red palm weevil and the
sperms transferred during the recent mating only aids fertilization. To counteract
the competition by wild males to mate with females, the irradiated males should
be flooded in the field with a ratio of 10 irradiated male insects per normal male in
the field.
In conclusion the experiment reveals the overall efficiency of plant products
and sterile insect technique to manage red palm weevil in coconut.