The field rat control campaign, Chiapas, Mexico
The Secretariat for Rural Development of the State Government of Chiapas, southern Mexico, has been charged with conducting a campaign against the field rat which began in February 1991. Four areas were identified as key sites for the campaign benefiting 3,355 farmers in a total area of 8,000 ha and an initial budget of approximately $500m Mexican pesos (US$170,000). The major crops for which damage is reported are maize, sugar cane and cacao. The term "field rat" is a general one encompassing any rodent causing damage to field crops and in Chiapas probably covers a variety of species; no studies have been done to identify the species or quantify losses to crops. Personnel had no previous experience in rodent control and no resources to permit preliminary investigations in the field. A method for assessing field damage levels was developed and fields were treated with zinc phosphide (high damage), diphacinone (medium damage) or untreated (low or no damage). A decrease in subsequent losses was reported by farmers involved in the campaign. The campaign in 1992 is restricted by financial and logistic constraints as the field rat campaign has been united with locust and other field pests in a single campaign entitled "Control of Pests to Basic Crops" with a much reduced budget overall. Problems found in the 1991 work and the limitations and of the campaign are discussed.