Domoguen: Managing and controlling rats as agricultural pests

THERE are field rats that taste like chicken. There are rats that fly, like the Palawan flying squirrel.

I am not joking, neither am I nuts for saying that some rats taste like chicken. I tasted barbecued rats myself in the early 70’s, at the height of the national shortage of rice during the Martial Law years.

That time, rice was rationed and it also came in the form of a rice-corn mix. Those days came back to mind while I was participating in a field lecture on the pest and diseases of rice in Tabuk City last month.

During those Martial Law days, we lived in the mines and the rationed rice-corn mix was not enough for a large family of five boys and two girls plus our parents. So my father and three of his grown-up boys went to Aluling, in Cervantes Ilocos Sur to get rice. We stayed three days in the farm and worked clearing the irrigation canal, weeding the fields, and drying and pounding rice. The old man who owned the rice fields did not accept cash as payment for the rice supply we needed.

While we stayed and worked, we learned that the farm-owner was a veteran soldier during the Second World War. He learned a lot of survival skills by experience as a combatant including what plants and animals to eat in the forest. I was not surprised when seeing that we caught rats in the rice fields, he told us not to waste them. “We can barbecue them for lunch,” he told us, “unlike the house rats that should be buried right away after hunting and exterminating them,” he added.

Today, I doubt if we should hunt rats or rodents to be barbecued. It seems to me, most of the rats we see in the fields are not the type that can be skinned for the purpose. The rats all look like house rats in appearance. I wish we asked the old man for more details.

Mr. Ulysses Duque, Center Chief Manager from the Crop Pest Management Division, Bureau of Plant Industry (BPI), in his lecture given to field technicians from the Department of Agriculture (DA), and local government units (LGUs) in Tabuk City says that rodents are one of the most important non-insect pests of agricultural crops, particularly rice.

The rodents seem to attack rice at all stages of its life cycle in the field. In addition to tiller cutting, the pest also hoards ripened panicles in their burrows. After the rice harvest, the rats thrive munching on the palay or rice in storage bodegas.

From the jungle to the agricultural fields and human dwellings in the countryside and urban areas, the rats are everywhere.

According to Duque, there are indeed many kinds of rodents. They comprise the largest group of mammals which accounts for about 40% with a cosmopolitan distribution. They can live in any terrestrial habitat including man-made, he said.

As of 2014, Dugue said that there are 86 native species of rats found in the Philippines and this number is still growing. Many are found in Luzon. He explained that in the Philippines, “currently 48 species of murid rodents have been reported and several of these species may be found living in and around rice fields.” He added that “only four rodent species are serious pests of rice, specifically, Rattus tanezumi which is the common rat pest of rice in the country. The other three are Rattus norvegicus, Rattus argentiventer, and Rattus exulans.

Interest on field rats in the Philippines is due largely to rice (Oryza sativa L.) being their food. And rice is also a major component of an average Filipino diet. It is currently grown by farmers on more than 3.2 million hectares of land.

Rice farming is a major source of income of more than two million households aside from millions of farm laborers, rice merchants, and middlemen as well. Every year, rats in Asia consume or destroy food crops that could feed 200 million people for an entire year.

Rats are also important because aside from destroying crops, they cause some diseases to humans. About 40 species of parasites were recorded in the Philippines to be spread through rats. They are also sources of diseases such as leptospirosis, rickettsial infections, arenaviruses, and hantaviruses.

Duque said that during food scarcity, which can be partly attributed to rat infestations, farmers tend to look for alternative food sources such as snails. However, snails are intermediate hosts of rat parasites which in turn infect the farmers.

The main distinguishing characteristic of rodents from other animals is the presence of two pairs of incisors in their mouth. These teeth continuously grow and need to be maintained short by gnawing or nibbling, which is the destructive behavior of rodents.

But while they share the same characteristic of gnawing, not all rats are a pest. The Chrotomys, in the rice field, for instance, feed and control earthworms and other insects. There are also rats that influence nutrient cycling, help in seed dispersal (musang), are a major part of the food web, used as laboratory test animals, pets, used in pest control, and are a source of protein.

There are rats that are friends to human beings, and there are those that need to be controlled.

To outsmart rodents, one must study their breeding biology. Studies done by Duque indicated that rodent breeding is high during the rice tillering and low at other growth stages of the crop.

Rat conception by adult females is high during the booting and ripening stages of the rice. The highest litter size of rats is at the ripening and stubble stages of the rice plants. The mean litter size is 6-8 per rat
The best way to manage and control rats is by employing multiple strategies combining biocontrol, mechanical, and chemical approaches to be effective. Rats can easily get used to just one way of control, Dugue said.

In the rice field, it is most effective to control rats when their population is at its lowest. This is during the growth stages particularly during the reproductive stage of the plant.

I hope we keep on managing and controlling rodents through any other effective means than resorting to eating them. By then, there is really lack or shortage of food. Robert Domondon
style="display:block; text-align:center;"
data-ad-layout="in-article"
data-ad-format="fluid"
data-ad-client="ca-pub-2836569479021745"
data-ad-slot="1977900730">



style="display:block; text-align:center;"
data-ad-layout="in-article"
data-ad-format="fluid"
data-ad-client="ca-pub-2836569479021745"
data-ad-slot="4158864647">


VIEW COMMENTS
DISCLAIMER:

SunStar website welcomes friendly debate, but comments posted on this site do not necessarily reflect the views of the SunStar management and its affiliates. SunStar reserves the right to delete, reproduce or modify comments posted here without notice. Posts that are inappropriate will automatically be deleted.


Forum rules:

Do not use obscenity. Some words have been banned. Stick to the topic. Do not veer away from the discussion. Be coherent. Do not shout or use CAPITAL LETTERS!

sunstar.com.ph