ASSESSMENT OF HEALTH AND GROWTH OF RING-NECKED PHEASANTS FOLLOWING CONSUMPTION OF INFECTED INSECTS OR CONIDIA OF ENTOMOPATHOGENIC FUNGI, Metarhizium anisopliae var. acridum AND Beauveria bassiana , FROM MADAGASCAR AND NORTH AMERICA

Abstract

Isolates of two fungi ( Beauveria bassiana and Metarhizium anisopliae var. acridum ) from Madagascar are being developed for control of grasshoppers and locusts, as part of a search for alternatives to environmentally detrimental chemical insecticides. The probable effects of these entomopathogens on nontarget species must be determined before operational use. Birds may become exposed to these fungi either directly, by consuming spores deposited on their food items, or secondarily, by consuming grasshoppers or locusts that have died from infection by these biocontrol agents. This article presents the results of per os challenge from fungus-infected food items. Male and female ring-necked pheasants ( Phasianus colchicus ) were exposed at 4 d of age and again at 9 d of age to challenge treatments, or 2 control treatments (18 male and 18 female birds per treatment group). Pheasants were weighed at 9, 17, and 25 d of age, tarsal length was measured at 25 d of age, and they were observed daily for signs of adverse effects of the experimental treatments. At the time of euthanasia (25 d of age), 2 or 3 randomly selected birds from each of the groups exposed to infected grasshoppers, plus the 2 control groups, underwent complete necropsies and histopathological examination of 16 tissues from each bird. Results show that in both sexes, weight gain at both 17 and 25 d was not significantly different between challenge groups and control groups. Tarsal length at 25 d of age, an indication of structural growth, was also not markedly different among challenged and control groups. Histopathological changes were generally undetectable, mild, or moderate, and not consistently associated with any treatment. Based on these findings, there is little indication that birds are susceptible to detrimental health effects from direct or secondary exposure to the two entomopathogenic fungi studied.