and Integrated Pest Management - part - usaid

ROLE OF INSETICIDES INRICE I1'M SYSTEMS 71
The potcncy of these predators is significant and therefore should be taken
into account during pest surveillance. When the control threshold is reached due
to the fast population buildup of the BPH, and the inability of the predator to
reduce the population density, any insecticide application should be effective on
the BPH population, but be relatively non-toxic to the predators. For this
purpose, extensive studies should be undertaken to identify the proper insecticide.
ECOLOGICAL DATA AND INSECTICIDE APPLICATION
A major insect pest, often causing serious damage to upland and dry seeded
rice, is the seedling maggot, Atherigona exigua. In several places, infestations
on young plants were between 20% and 40%. The most favorable stage for
infestation is between 4 and 10 days after planting. Older plants suffer less
damage than younger plants. The recommended control was previously to dust
daily with 5% B1-C dust up to one week after the seedling had emerged.
Recent studies (Soekarna 1981) indicated seed treatment of rice seed just
before planting with carbofuran, carbosulfan, and thiodicarb reduced seedling
maggot damage by 20-80% (Tables 4, 5). This tactic can be recommendcd
selectively in places where seedling maggot is a major pest, since no resistant
rice varieties are available yet. Seed treatment is more practical and economical
than spraying and dusting.
Table 4. Efficacy of carbofuran 30 ST as seed treatment to control seedily,
Atherigonaexiguaa. Field experiment, 1980/1981.
Dosage Seed emergence Seedily Yield
Treatment a.i./kg/seed 8 dapb infestation kg/ha
10 dap 20 dap
Carbofuran 30 ST 0.5 99 a 0.42 a 3.65 b 1,976 ab
Carbofuran 30 ST 1.0 98 a 0.30 a 1.20 a 2,166 ab
Carbofuran 30 ST 1.5 95 a 0.68 a 2.20 ab 2,379 a
Carbofuran 30 ST 2.0 97 a 0.25 a 0.73 a 2,382 ab
Carbofuran 30 ST 2.5 98 a 0.04 a 1.11 a 2,382 ab
Carbofuran 30 ST 3.0 97 a 0.14 a 0.83 a 1,774 ab
Carbofuran 30 ST 3.5 97 a 0.20 a 0.50 a 2,632 ab
C h e c k - 80 b 27.54 b 85.98 c 702 c
a from 3 replicates. bdap = day after planting. In a column, meins followed by
the same letter are not significantly different at the 5% level using Duncan's
Multiple Range Test.