Natural Crop Protection in the Tropics: Rodents

Damage by rodents is tremendous, both in the field and in the store. In India alone, ca. 7 to 8 million tons of food grains are lost every year due to rodents. In rice cultivation they can cause great damage during panicle initiation. Keeping rodents under control is not only an individual's business, but it can also assume a larger social dimension. In 1998, the Vietnamese government, for instance, conducted a national campaign against rodents. Key in this campaign was that each capable individual was requested to contribute to killing rodents and collect the rodent tails as a 'trophy'. This was a very good example of a well orchestrated public campaign to control a pest which could not be successfully kept in check at individual farmers' level.

In order to make rodent control more successful, GALLAGHER (174) suggests to consider the following general principles based on his working experience:

1. "Know thy enemy"

Farmer groups can study the characteristics of rodents – longevity, fecundity, bait shyness, swimming ability, nest structure, local migration/movement trails, population levels with trap and release, teeth configuration, etc. This helps to demystify and to make control plans easier. Apparently different species have different bait preferences including taste, texture, and size of bait (e.g. large blocks vs. smaller grains).

2. "Know thy territory"

is another principle that comes with community mapping and marking of preferred living sites and movement. This should be done for various seasons as food resources and habitat change over the year.

3. "Prepare thy arsenal"

with testing of traps, baits, digging, smoking, and barriers for fields and storage. This technical part seems to be where many programmes begin – but is only one aspect. One programme in Sumatra was called "One million traps" and communities literally made one million traps in the area. Be prepared to modify habitat to reduce nesting sites.

4. "Be smarter than the rodents themselves"

which is not easy! Getting organized into 'rodent patrols' to prepare village sub-units to monitor, trap, bait, and dig holes on a regular long term basis is important. Keeping village records, maps, and reporting are part of the rodent patrol job. One village person should be the "Rodent King" (or some other socially appropriate name). Prepare a rodent manual in the village for future reference on how it was all done when rodents emerge as a problem again.

These seem to be common points. The key to successful programmes seems to be 'prolonged organization'. Rodent campaigns give temporary relief, but rodents spring back. Eradication is useless unless you live on an island. High tech, low tech, appropriate tech and other techs are all useless without sustained action over time.

Below, methods are presented on the use of plants in rodent control. Most of these are based on farmer knowledge, very few are scientifically verified. Therefore, it is suggested to verify this information first before disseminating it.

The printed version contains descriptions of the following plants

Chilli (Capsicum frutescens)

Elephant apple(Limonia acidissma)

Papaya (Carica papaya)

Physic nut (Jatropha curcas)

Cenchrus mungo

“Madreado” (Cliricidia sepium)

Ipomoea fistulosa

Mint (Mentha cordifolia)

Neem (Azadirachta indica)

Oleander (Nerum oleander)

White-spot giant arum (Amorphophallus campanulatus)

Baits & traps

Increase predation

Other methods