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.

Safety of Beauveria bassiana (Bals.) Vuill. to Gallus domesticus L.

“…Relating to the birds behavior, all the individuals presented the same pattern with no deviations from the normal (Table 1). Similar results were found by Johnson et al (2002) Laird (1990), these entomopathogens are specific, which reduce the risk of infection of species in different taxonomic classes from the target species. Pereira et al (1998) asserted that it happens due to the great difference between the physiology of the organisms, as the body temperature of the birds (40ºC), much higher than the insects' organism.…”

“…Rezende (2009), testing the effect of oral administration of B. bassiana in broiler chickens, also found no statistical significatively difference in weight gain. Johnson et al (2002) did not find evidence that the consumption of infected grasshoppers with M. anisopliae and B. bassiana by male pheasants (P. colchicus) had affected the weight gain of the birds.…”

“…However, Smits et al (1999) disagreed with these results, mentioning that they did not observe M. flavoridae conidia in the feces of pheasants treated with this fungus in its food. Johnson et al (2002), evaluating the same species (P. colchicus), were not able to find other fungi than Mucor and Penicillium when analyzing feces and blood of the birds fed with B. bassiana and M. anisopliae. Although, the authors explained that, appraising samples of the birds' diet, a small number of viable conidia were found.…”

“…Samples from the lungs, heart, small intestine, kidney and liver were collected. These tissues were fixed in 70% alcohol and embedded in paraffin blocks, sectioned at 7 µm and stained with HE (Hematoxilin and Eosin), following techniques from Ganter and Jolles (1970) and Behmer et al (1976) to verify possible lesions caused by the fungus, as alterations to normal cellular structure, inflammation or necrosis of the tissue (Johnson et al, 2002). The experimental design was completely randomized with three treatments (control, active fungus and inactive fungus) and ten replications.…”

“…Any evidence of gastrointestinal disorder (vomition or diarrhea) (Johnson et al, 2002) or skin lesions were verified. The birds' weight was measured before the fungus administration and on the days 0, 7, 14 and 28 days after the ingestion (DAI).…”