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.