FIELD RATS AND MOUSE IN MALAYSIA (PART 2)

RAT or TIKUS (in Malay) was a medium-sized and long-tailed rodents. Rat species are found throughout the order Rodentia. Stereotypical rats are found in the genus Rattus in which it includes some of the better-known species of rat such as the brown rat (Rattus norvegicus) and the black rat (Rattus rattus). As I know the Rice-field rat or known as the Malayan wood rat, the T greater bandicoot, greater bandicoot, the lesser bandicoot and the rice-field mouse are serious pests of ricefields, oil palm plantations and other field crops in Malaysia. These same five species are distributed throughout Southeast Asia. The ricefield rat and the Malaysian wood rat used to be treated as subspecies of Rattus rattus and were known as Rattus rattus argentiventer and Rattus rattus jalorensis. They are now recognized as separate species (Rattus argentiventer) and Rattus tiomanensis respectively. The bandicoots are large ground rats that build extensive burrows. In Malaysia two species occur they are the greater bandicoot (Bandicota indica) and the lesser bandicoot (B. bengalensis). The fifth species is the field mouse (Mus caroli) similar to the house mouse (Mus musculus) in size. In the question of what rat does in rice field usually the rats cut or pull up transplanted plants. They also chop down the young seedlings. At booting stage, they feed on rice panicles. On the other hand, during ripening stage, they feed on developing rice grains. Rats are found in lowland irrigated rice crops. Both the wet and dry seasons are favorable for rat reproduction and crop damage. In rainfed rice crops rodents have their greatest impact in the wet season. The availability of food, water, and shelter are the factors, which provide optimum breeding conditions. The presence of grassy weeds also triggers their development. Rice field rats feed at night with high activity at dusk and dawn. At daytime, they are found among vegetation, weeds, or maturing fields. During fallow period, they utilize major channels and village gardens as prime habitats. At tillering, 75% of time they are in burrows along the banks and after maximum tillering, 65% of time they are in rice field or paddies. Rat damage in the rice crop can be observed by the following symptoms such as missing germinating seeds, missing hills chopped young seedlings, missing plants, irregular cuttings of stem, chewed developing buds or ripening grains, tillers cut near base at 45° angle, retillering of stems, delayed grain maturity, missing grains and missing panicles. The feeding damage on the stem caused by the rice field rats may resemble insect damage although rat damage is usually distinguished by the clean cut at 45° of the tiller. The damage on the grains is similar to bird damage. Check muddy areas for runways, active burrows, and footprints of rice field rats. These are usually near the damage they have created. Check for presence of rice field rats: cut tillers and active holes on the bunds that surround the fields. When possible, catch rats to identify the species. Place traps along runways, or dug the rats from their burrows. This technical article in "Anim Agriculture Technology" I wrote about field rats and their species that found in Malaysia as a source of agronomic practices for all.

(3) THE GREATER BANDICOOT (Bandicota indica)

This species is a very large rat with HB length 200- 350 mm, T 180-290 mm, and dark brown with relatively large scales. HF 40-60 mm, blackish with long whitish claws. Weight (Wt) 350–600 g. Upperparts blackish-brown with long black guard hairs. Underparts dark brownish grey, giving a shaggy appearance. Mammary tits 12. Distribution and status: In Malaysia, this rat was first recorded as pests in rice fields of Kedah and Perlis in 1946. In Southeast Asian countries it is found in Myanmar, Thailand, Vietnam, Loas, Cambodia, Indonesia (Java, Sumatra) and the Philippines. The species was introduced to Southeast Asia from East Asia. Ecology and Habitat: Nocturnal, terrestrial and omnivorous. The natural diet is plant material, insects, earthworms, mollusks and crustaceans. Some individuals have been found with remnants of skeletons, probably tiny lizards, and scales of fish. It builds extensive burrows, leaving piles of earth mounds on the surface. Sometimes, the burrow is occupied by several pairs of adults and young together. Nests have also been found in termite moulds. It has a habit of a hoarder, storing young rice plants and other food materials inside its burrows. It lives near human activity and swims well.

(4) THE LESSER BANDICOOT (Bandicota bengalensis)

This is a medium sized rat with HB 150-210 mm, T 110-160 mm uniformly brownish, HF 34–38 mm brownish, Weight 200-350 g. Upperparts of body brown intermixed with long dark guard hairs, giving a shaggy appearance. Underparts grayish-white to brownish. The mammary tits vary from 12-20 and arranged in a continuous row down each side of the body, and not always the same number on each side. The description of this rat is based on specimens collected in Pulau Penang. Distribution and status: In Malaysia, the lesser bandicoot rat is found in Pulau Penang. It is also present in Myanmar, Thailand and Indonesia. The species was introduced into the Southeast Asian countries from East Asia. Ecology and habitat are as Nocturnal, terrestrial and omnivorous. In Pulau Pinang this rat is associated with human surroundings and is found as an outdoor resident in towns and villages. It is a scavenger like the Norway rat (Rattus novegicus) wherever food is available. It builds an extensive burrow system like the greater bandicoot rat, sometimes with large families living together and it often stores food. It lives outdoors probably because of competition with the common house rat (Rattus rattus diardii) in which it dominates indoors.

(5) THE RICEFIELD MOUSE (Mus caroli)

This species is a tiny mouse with HB 60-85 mm, HF 15-19 mm, Tail length 60-95 mm with body weight 8-15 g. Hairs short and smooth. The tail is bicolored, dark gray above and whitish below. Upperparts of body brownish gray with the underparts whitish. Feet dark gray to whitish. In size and structure, it is similar to the house mouse (Mus musculus), but differs by coloration. Mammary tits 10. Distribution and status found in Malaysia and it is an introduced species found in rice fields in Kedah. Among the Southeast Asian countries, the species is known in Myanmar, Vietnam, Laos, Cambodia, Thailand and Indonesia. The species is common in East Asia. Ecology and habitat: Nocturnal and terrestrial. It inhabits rice fields and grasslands adjacent to rice fields. It digs small holes in mud banks for nests. Its diet is mainly planting material but also includes insects. This article devided in three segments namely Part 1, Part 2 and Part 3 respectively. Thanks...

By,

M Anem,

Senior Agronomist,

Putrajaya,

Malaysia.

(January 2024).

Posted from:

Hotel Impiana, Senai,

Johor Bahru, Johor.