Aflatoxin poisoning, like botulism poisoning, is a case of food poisoning . However, it is slightly different than the carcass - maggot cycle of botulism poisoning, wherein the wildlife are affected by feeding on toxin - containing insects. In the case of aflatoxin poisoning, the wildlife ingest plant products that contain high levels of afl atoxin. Like botulism, this disease is not truly infectious, but caused by a biotoxin.
So what is the role of insects in this disease? Aspergillus fungi develop in cereal grains when plants are stressed or damaged. Hot, dry weather is stressful to plants, as is damage by insects, hail, and early frost. The products normally affected by aflatoxin are cereal grains and oil seeds, particularly corn, rice, sorghum, cottonseed and peanuts. Insects also serve to move the fungus around from plant to plant in the field, or within stored grains as they feed. Even aflatoxin - free grain can become heavily contaminated if it is not stored properly after harvest. Insect infestation in stored grain causes increase in moisture levels within grain. Increased moisture levels facilitate growth of fungi including Aspergillus , and production of heat, which promotes more growth of Aspergillus , as optimal growth of this fungus occurs at 26 – 32 ° C.
How important is aflatoxin poisoning to free - ranging waterfowl? Following are some examples of poisoning in the USA. In the winter of 1977 – 1978, approximately 7500 ducks and geese were killed in Texas following ingestion of crop residue, with corn and rice recovered from the digestive tract of the dead birds containing 500 ppb of AFB 1 . Similarly, in 1998 – 1999 approximately 10,000 waterfowl died in Louisiana after eating affected corn. Corn intended for consumption by mature poultry is not allowed to have over 200 ppb of aflatoxin, so clearly these wild birds ingested too much aflatoxin. Survey of residual corn in farmers ’ fields, or planted for wildlife, has shown that such grain may contain high levels of aflatoxin. For example, 32% of the corn growing near the Mississippi Sandhill Crane National Wildlife Refuge was found to contain over 200 ppb of AFB 1 , and corn grown in southern Georgia and northern Florida to provide food for quail and other wildlife was found to contain up to 1200 ppb of AFB 1 . Corn used to feed deer in North Carolina and South Carolina was found to contain 750 ppb of AFB 1 , and even birdseed sold for home bird feeding has been found to contain aflatoxin.
Considerable potential exists for wildlife to be poisoned unintentionally by cultivated crops. Indeed, it is estimated that 25% of the world ’ s food supply of grains is contaminated with aflatoxin, with contamination being higher in developing than industrialized countries. Also, the rate of aflatoxin infection is higher in warm, wet production areas such as the southeastern USA, where phytophagous insects abound. Numerous species have been poisoned by afl atoxins, including fi sh, birds, and mammals. Young animals are more susceptible than old animals, and animals such as rats and rabbits that metabolize the metabolites rapidly are more susceptible than those that metabolize the aflatoxin slowly. Serious poisonings have involved snow geese, Chen caerulescens ; Ross ’ s geese, Chen rossi ; greater white - fronted geese, Anseralbifrons ; mallards, Anas platyrhynchos ; northern pintails, Anasacuta ; and ring - necked pheasants, Phasianus colchicus , among others.
