Results
A total 2499 individual bats from 6 Orders and 27 species were captured.
1608 individuals from 6 Orders and 21 species were recorded for the dry
season and 891 individuals from 5 Orders and 23 species were recorded
for the wet season (Table 1). Rhinolophus pusillus was recorded
as the dominant bat species with the highest capture rate in the dry
season as well wet season. Throughout this study, a few single
individuals of rare bats were encountered and species that had never
been recorded previously at Gunung Keriang. These wereHipposideros halophyllus and Rhinolophus marshalli .Miniopterus magnater and Scotophilus kuhlii are a few open
space bat species that were captured in the dry season. In the wet
season, single individuals of Macroglossus minimus andCynopterus sphinx , the frugivorous bats, were caught.
Based on the correlogram, the results show that the bat activity was
positively correlated with the average temperature and negatively
correlated with maximum temperature and rainfall (see diagnostic plot in
Suppl. Mat. Table 1). The insect activity was positively correlated with
minimum temperature and rainfall (Figure 2). The multiple linear
regression model met the conditions of validity (see diagnostic plot in
Suppl. Mat. Figure 1).
The coefficient of determination, R² is 0.35, therefore this indicates
that 35% of the variance in bat activity can be explained by the
predictors based on the model (Figure 3). The coefficient value for
minimum temperature is significant with a p-value of 0.007 while
rainfall is significant with a p-value of 0.002. Regression analysis for
the five bat species separately did not return statistically significant
results and were therefore discarded.
For the dry season, 12 Orders of insects were recorded at the rice
fields (Figure 4) and the dominant insect Order was Coleoptera. The
germination phase of the paddy had the highest insect abundance compared
to the rest of the paddy phases. Chilo polychrysus (Stem borer)
from the Order Lepidoptera is the insect pest species that was captured
for all phases of paddy growth in the dry season.
Meanwhile for the wet season, 13 Orders of insects were also recorded at
the rice fields (Figure 5). The dominant insect Order for this season is
Homoptera. The vegetative phase recorded the highest insect abundance
compared to the rest of the paddy phases. Nilaparvata lugens(Brown planthopper) from the Order Hemiptera is the insect pest species
that was captured for all phases of paddy growth in the wet season.
Insects from the Orders Araneae and Odonata have also been captured in
the dry and wet season. These two insect Orders are known to be natural
enemies of insect pests in rice fields. From the Order Araneae,Lycosa pseudoannulata was the most common species captured and
for the Order Odonata, Agriocnemis sp. was the most common
species captured. The most common natural enemies of insect pests in
rice field area are Ophionea sp., Paederus fuscipes ,Harmonia octomaculata , Euborellia stali , Limnogonous
fossarum and Riptortus linearis .
Peak time of insect emergence with the highest individuals captured for
dry season was from 20:00 until 21:00 while for wet season, 19:00 until
20:00 (Figure 6). This time frame is expected to be the same as peak
time of the bat foraging activity. The time of bat emergence in the dry
season was from 19:00 until 21:00 while for wet season was from 20:00
until 21:00.