Nerium oleander historically has been known worldwide as a poisonous plant that can be used to control pests. However, studies on the effects of oleander leaves against Rattus argentiventer as a major agricultural rodent pest are limited. This research aimed to probe the potency of oleander leaves extracted in methanol as a rice-field rat repellent. The experiments involved a choice test (T-maze arena) and a no-choice test (metabolic cage) that were analyzed by the T-test using three replications for 6 days. The results showed that the rats on the T-maze avoided consuming food and water near the oleander treatment. The same results occurred in the metabolic cage, which was indicated by a decrease in the average of food and feces, and also by an increase in the average of water and urine. Additionally, the treatment also caused a disruption in daily activity patterns, which was significantly indicated by an increase of 22.84% in average time for resting activities and a decrease in time for locomotion and nesting activities (by 9.71% and 13.13%, respectively). Overall, oleander leaves have the potential to provide a repellent effect against rice-field rats, especially in the choice test.

Foraging by rice-field rats (Rattus argentiventer) can significantly reduce rice harvest. Rat populations are cyclic responding to season and crop maturity. Rat location also reflects the crop cycle. A study conducted near Sukamandi, Indonesia described rice-field rat burrow systems and patterns of use, and assessed demographics of rice-field rats found in burrows adjacent to rice fields. Burrows ranged from simple short tunnels to complex systems. Most simple systems consisted of a straight tunnel approximately 75 cm long. Mean tunnel length of more complex systems was approximately 300 cm, but a few contained tunnels up to 700 cm. Burrow systems had between 1 and 5 entrances, with 0 to 8 choice-points within the system. A choice-point was defined as any place within the system where the animal could choose a different path (e.g., Y in the tunnel, nest). Number of chambers within systems also varied, ranging from none to six. There was no correlation between rat activity within a system, measured by the closed-hole method, and complexity of the system. Long-term monitoring suggested both male and female rats occupied burrow systems along rice banks, except relatively short periods during spring (March, April) and early fall (September) when burrows were used almost exclusively by females. These periods appear to correlate when high numbers of female rats are gestating and lactating.

Rodent damage is commonly concentrated towards the center of rice fields. There are some approaches to assess the damage, two of them are the transect and the Malayan method. The transect technique is a well-known applicable practice employed among agricultural workers in Indonesia, while the Malayan method is generally performed in Malaysia. The objective of this study was to compare both methods in terms of determining the more representative technique for assessing rodent damage. The study was conducted in Karanggetas village, Bangodua subdistrict, Indramayu district, West Java (6°51’S, 108°29’E) in 2018. Two plots (0.35 ha and 0.56 ha) were selected as the study site which was planted with Inpari 32. Since the generative stage of the rice crop is the most preferable phase for rodents, therefore we solely observed the damage within this period. We recorded the damage intensity four times with weekly intervals by both methods in each plot. To confirm the rodent population and reproduction status, we installed a linear trap barrier system and dug some active burrows along the irrigation channel bank as their main habitat. The result showed that the damage intensity was significantly different between both methods. The damage intensity was higher when it was assessed by the transect method compared to the Malayan one. The result indicated that the transect method is a better technique representing the damage than the Malayan method. This due to the first method covered almost entirely the damaged spot. This finding suggested that the transect method is the representative technique for assessing rodent damage intensity.