Development and Life History of Sitophilus zeamais (Coleoptera: Curculionidae) on Cereal Crops
Table 3
Head capsule width for larval instars of S. zeamais and test for conformity to Dyar’s rule (24–30°C; 60 ± 10% RH; 12 h photophase).
Instar
Maize
Rice
Sorghum
Millet
Observed average (mm)
Growth ratio
Calculated average
Differences
Observed average (mm)
Growth ratio
Calculated average
Differences
Observed average (mm)
Growth ratio
Calculated average
Differences
Observed average (mm)
Growth ratio
Calculated average
Differences
I
0.24
0.23
0.24
0.23
II
0.28
1.17
0.32
−0.04
0.27
1.17
0.30
−0.03
0.28
1.17
0.31
−0.03
0.28
1.22
0.29
−0.01
III
0.37
1.32
0.37
0.00
0.35
1.30
0.35
0.00
0.37
1.32
0.36
0.01
0.37
1.32
0.35
0.02
IV
0.54
1.46
0.49
0.05
0.47
1.40
0.45
0.02
0.52
1.40
0.48
0.04
0.47
1.27
0.47
0.00
Mean growth ratio
1.3
1.3
1.3
1.3
Average difference (d)
0.0033
0.0033
0.0067
0.0033
Standard deviation of differences
0.026
0.0153
0.0153
0.01
calculated
0.379
0.647
1.314
1.000
tabulated
3.182
3.182
3.182
3.182
Reject Ho if calculated > tabulated. Decision: do not reject Ho; growth ratio conforms to Dyar’s rule. Note: growth ratio—the mean head capsule width of a succeeding instar divided by the mean head capsule width of a preceeding instar. Calculated average—observed mean head width of a preceeding instar multiplied by the mean growth ratio.
