and Integrated Pest Management - part - usaid

SAMPLING W-TMODS FOR PES3T SURVEILLANCE-INRICE 117
GALL MIDGE
hill with gollsdI
hill without .0
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2­
3­
P ,o0 IoS 5 /,.o,
5
7
-
0
5
6 -6 -- 5
Wi U
E-
20-9 1
IO I 1
12 2
6
7
8
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7 Z i +
15 T R F ,T 13
15
2 -- 8
3 -- 9
D"L
16 3 -- 9
x. 18 4 _to
5
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12
D
S19
O¢, €.. "20
N I[AMFT
21
2
23
5 _ 11
5 11
6 - 11
6 __12
6 12
,,,.jF~i IEMMNT 24 7 " 13
10 20
NUMBER HILLS SAMPLED (n)
30
25
26
27
28
29
30
7
8
8
9
9
__ 13
14It
_ 14
__14
Ii
__15
Figure 4. Binomial sequential sampling plan for gall midge in transplanted rice.
Table 1. Field testing of the stemborer and gall midge sequential sampling
plans.
(a) Agreenent in control decision
20 sample unitsa 10 sample units
Treat No trmt Treat No trmt
Treat 36 2 31 7
(52%) (3%) (45%) (10%)
Sequential
sampling No trmt 3 28 2 29
(4%) (41%) (3%) (42%)
(b) Averace sampling time per field (minutes)
20 sampling units 10 sampling units Sequential
10+1) 5 + 3.1
a sample unit = lbill; 11+ = time needed for calculation not included.
A relatively good agreement betwcen sequential sampling and the systcmatic
sampling method, with 20 units, was obtained; and in 13% of the cases, the
scqucntial method led to a control decision different from the fixed sample size of
10 hills. "The latter failed to indicate the need for chemical control in several
fields. Thus, the data in Table I illustrate the benefits of sequential sampling in