Table 1. Number of positive sites and collected individuals of non predaceous mosquito immatures from summer
and autumn surveys on 171 and 124 containers, respectively.
significant positive and negative coefficients for
environment and area, respectively, were estimated but
the coefficient for season was not significant.
Culex kyotoensis occurred in relatively large
containers and most frequently in shaded sites (Figures
1 and 2; ranged from 0.0016 to 0.614 m2
, summer and
autumn combined), as expressed with significant
positive coefficients for environment and area in the
logistic regression (Table 3). The frequency of
occurrence of Cx. kyotoensis decreased from summer
to autumn, as indicated by a significant negative
coefficient for season in the logistic regression (Table
3).
Culex tritaeniorhynchus and An. sinensis occurred
frequently in rice fields but rarely in containers in
summer (2 and 1 containers, respectively). However,
in the autumn, these species occurred frequently mainly
in large containers (Figure 2). The ranges in area of
containers with these species were 0.0452 – 14.75 m2
and 0.33 – 14.77 m2
for Culex tritaeniorhynchus and
An. sinensis, respectively. These two species showed
similar coefficients for the logistic regression (Table
3). Both species showed significant positive
coefficients for area and season, and non-significant
coefficients for environments.
Compared to non-predaceous mosquitoes, the
occurrence patterns of predators in relation to size and
environment appeared to be uniform. They occurred
mostly in relatively large containers in open sites but
infrequently in small containers and in bamboo groves
(Figures 3 and 4). In the logistic regression, all of the
5 predator groups showed significant positive
coefficients for area (Table 3). The ranges in container
size in which these predators occurred were: 0.221 –
14.77 m2
for Notonectidae; 0.044 – 14.77 m2
for
Anisoptera; 0.045 – 14.77 m2
for Chaoborus sp.; 0.04
– 14.75 m2
for Veliidae; 0.004 – 14.75 m2
for Cx.
halifaxii (summer and autumn combined).
Notonectidae, Anisoptera, Chaoborus sp. and Veliidae
showed negative, but not significant, coefficients for