REDUCTION IN RODENT POPULATIONS THROUGH INTERMITTENT CONTROL OPERATIONS IN THE CROPPING ECOSYSTEM OF THE INDIAN DESERT

Control operations at 6-month intervals, continued for four years in crop fields, reduced the rodent population to 5.08 percent losses to agricultural production. After eight crop seasons, a significant reduction in rodent density was observed in treated areas when compared with that of the control areas (P < 0.01). Correlation between pre-treatment population index (y) and number of seasons (log of x) was found to be 0.91 (P < 0.01). A relationship was established between y and x : y = 0.804.0-0.9621 log x. From this equation, it can be inferred that rodent population will reach zero level after treating crop fields continuously for6.85 or say 7.0 (seven) seasons. After control, the numbers of predominant rodents, Tatera indica, Meriones hurrianae and Rattus meltada. were significantly reduced and the residual population was composed of Mus booduga. Gerbillus spp., Rattus gleadowi. Golunda ellioti and Funambulus pennanti.

Prairie Dog Empire: A Saga of the Shortgrass Prairie

For hundreds of years black-tailed prairie dogs inhabited the Great Plains by the millions, improving the grazing for bison and pronghorn antelope, digging escape holes and homes for burrowing owls and rodents, and serving as prey for badgers, coyotes, hawks, and bobcats. This book by the renowned naturalist and writer Paul A. Johnsgard tells the complex biological and environmental story of the western Great Plains under the prairie dog’s reign—and then under a brief but devastating century of human dominion. An indispensable and highly readable introduction to the ecosystem of the shortgrass prairie, Prairie Dog Empire describes in clear and detailed terms the habitat and habits of black-tailed prairie dogs; their subsistence, seasonal behavior, and the makeup of their vast colonies; and the ways in which their “towns” transform the surrounding terrain—for better or worse. Johnsgard recounts how this terrain was in turn transformed over the past century by the destruction of prairie dogs and their grassland habitats, together with the removal of the bison and their replacement with domestic livestock. A disturbing look at profound ecological alterations in the environment, this book also offers a rare and invaluable close-up view of the rich history and threatened future of the creature once considered the “keystone” species of the western plains. Included are maps, drawings, and listings of more than two hundred natural grassland preserves where many of the region’s native plants and animals may still be seen and studied. This excerpt includes the Preface and Chapter 1, "The Western Shortgrass Prairie: A Brief History."

HAWAIIAN SUGAR CANE RAT CONTROL METHODS AND PROBLEMS

The problem of rats in our Hawaiian sugar cane fields has been with us for a long time. Early records tell of heavy damage at various times on all the islands where sugar cane is grown. Many methods were tried to control these rats. Trapping was once used as a control measure, a bounty was used for a time, gangs of dogs were trained to catch the rats as the cane was harvested. Many kinds of baits and poisons were used. All of these methods were of some value as long as labor was cheap. Our present day problem started when the labor costs started up and the sugar industry shifted to long cropping. Until World War II cane was an annual crop. After the war it was shifted to a two year crop, three years in some places. Depending on variety, location, and soil we raise 90 to 130 tons of sugar cane per acre, which produces 7 to 15 tons of sugar per acre for a two year crop. This sugar brings about $135 dollars per ton. This tonnage of cane is a thick tangle of vegetation. The cane grows erect for almost a year, as it continues to grow it bends over at the base. This allows the stalk to rest on the ground or on other stalks of cane as it continues to grow. These stalks form a tangled mat of stalks and dead leaves that may be two feet thick at the time of harvest. At the same time the leafy growing portion of the stalk will be sticking up out of the mat of cane ten feet in the air. Some of these individual stalks may be 30 feet long and still growing at the time of harvest. All this makes it very hard to get through a cane field as it is one long, prolonged stumble over and through the cane. It is in this mat of cane that our three species of rats live. Two species are familiar to most people in the pest control field. Rattus norvegicus and Rattus rattus. In the latter species we include both the black rat and the alexandrine rats, their habits seem to be the same in Hawaii. Our third rat is the Polynesian rat, Rattus exlans, locally called the Hawaiian rat. This is a small rat, the average length head to tip of tail is nine inches and the average body weight is 65 grams. It has dark brownish fur like the alexandrine rats, and a grey belly. It is found in Indonesia, on most of the islands of Oceania and in New Zealand. All three rats live in our cane fields and the brushy and forested portions of our islands. The norway and alexandrine rats are found in and around the villages and farms, the Polynesian rat is only found in the fields and waste areas. The actual amount of damage done by rats is small, but destruction they cause is large. The rats gnaw through the rind of the cane stalk and eat the soft juicy and sweet tissues inside. They will hollow out one to several nodes per stalk attacked. The effect to the cane stalk is like ringing a tree. After this attack the stalk above the chewed portion usually dies, and sometimes the lower portion too. If the rat does not eat through the stalk the cane stalk could go on living and producing sugar at a reduced rate. Generally an injured stalk does not last long. Disease and souring organisms get in the injury and kill the stalk. And if this isn't enough, some insects are attracted to the injured stalk and will sometimes bore in and kill it. An injured stalk of cane doesn't have much of a chance. A rat may only gnaw out six inches of a 30 foot stalk and the whole stalk will die. If the rat only destroyed what he ate we could ignore them but they cause the death of too much cane. This dead, dying, and souring cane cause several direct and indirect tosses. First we lose the sugar that the cane would have produced. We harvest all of our cane mechanically so we haul the dead and souring cane to the mill where we have to grind it with our good cane and the bad cane reduces the purity of the sugar juices we squeeze from the cane. Rats reduce our income and run up our overhead.