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Pathogenicity of externally occurring fungi to Reticulitermes flavipes
266
NOTES
foot. These could, of course, also represent multicentric primary foci of infection. The epithelial covering of the foot terminated at the base of the polyp and was absent from its surface (Figs. 2, 3). In some sections the basement membrane of the epithelium could be seen over most of the growth. Essentially the same features described above were present in the smaller papilla on the edge of the foot, except that the surface projection was cone-shaped. Summarizing, these exophytic lesions on the foot of a gaper clam apparently represent exuberant inflammatory and reparative proc-
Pathogenicity
esses. They contain unclassified microorganisms that were either primary or secondary invaders. It would be of value to know whether similar lesions occur endemically in natural populations of this species, and if so, to learn the natural history of the disease. RONALD ALBERT
1 Approved for publication by the Director of the Wisconsin Agricultural Experiment Station. This work was supported in part by the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation, and in part by the U.S. Department of Agriculture, Forest Service Contract No. 12-11-012-560 (5).
C.
TAYLOR SMITH
Division of Biological Sciences University of California Irvine, California Accepted January
of Externally to Reticzditermes
Wood eaten by termites frequently shows evidence of fungal attack and termites are probably effective disseminators of fungus spores and hyphae. E. C. Hendee (Univ. CaZif. Pub. Zool., 39, 111-134, 1933) isolated representatives of 33 genera and 20 unidentified fungi from colonies of Reticulitermes hesperus, Kalotermes minor, and Zootermopsis angusticollis. The fungi were isolated from the guts, the exteriors of the termites, and from their tunnels. Marion Brooks (In E. A. Steinhaus, “Insect Pathology,” Academic Press Inc., New York, 1963) stated that externally borne fungi (of insects) are known poorly if at all. In the process of a much broader study, seven species of fungi were isolated externally from Reticulitermes fiavipes (Kol-
L.
Occurring jhipes’
2.5, 1966
Fungi
lar) and all were pathogenic under laboratory conditions. The fungi were identified by M. P. Backus, Department of Botany, University of Wisconsin, Madison, Wisconsin. Fifty termites, collected the same day in Janesville, Wisconsin, were chilled and shaken singly in vials of physiological saline which was then streaked over plates of malt agar and potato dextrose agar. Fungi were isolated from 15 termites only (30%). Plate cultures of the fungi were allowed to grow and sporulate for 2 weeks at which time 25 adult workers of R. flavipes were introduced to each culture. After 5 minutes the termites were removed from the cultures and incubated in closed circular plastic containers lined with moistened filter paper. For each group of 25 termites, 20 were incubated in one container and five were incubated singly. The results (Table 1) showed that the insects incubated singly suffered significantly greater mortality than those incubated in groups, except in those containers containing two species in the genus PenicilEium. With
267
NOTES
TABLE OF Reticulitermes
MORTALITY
OF SEVEN
flavijes
WHEN
EXTERNALLY
ISOLATED
Number
Fungi Gliomastix sp. Group of 20 5 (incubated singly) Cunninghamella echindata Group of 20 5 (incubated singly) Cephalosporium sp. Group of 20 5 (incubated singly) Paedomyces varioti, strain Group of 20 5 (incubated singly) Paecilomyces varioti, strain Group of 20 5 (incubated singly) Penicillium sp. (Asymmetrica Group of 20 5 (incubated singly) Penicillium oxalicurn Group of 20 5 (incubated singly) Penicillium freqentans Group of 20 5 (incubated singly)
TO SPORULATING FUNGUS
dead
PLATE
CULTURES
SPECIE@
at various (days)
intervals
1
2
4
6
Percent dead _-..-
0 0
0 0
0 3
2 3
10 60
2 4
2 5
4 5
4 5
20 100
1 0
1 0
1 3
1 4
5 X0
0 2
0 5
3 5
3 5
15 100
1 0
1 2
3 5
4 5
20 100
10 2
20 2
20 4
20 4
100 SO
5 2
20 2
20 2
20 3
100 60
0 0
0 0
4 2
4 3
20 60
0
0
0
0
0 ----
1
2
divaricata)
Check a The termites
1
EXPOSED
were incubated
both in groups
of 20 and singly.
these fungi the termites incubated in groups nificance of the pathogenicity reported herein were slightly more affected than those in- is not known. cubated singly. Considerable grooming acR. V. SMYTHE tivity was observed among the termites Wood Products Insect Lab. incubated in groups, and this probably ac- Box 2008 counted for much of the mortality difference Guljport, Mississippi beween the two modesof incubation. Though H. c. COPPEL R. flavipes apparently carries numerous funDepartment of Entomology gus spores externally on its body, it likely University of Wisconsin never or rarely encounters a concentration Madison, Wisconsin of sporesin nature similar to that provided in the laboratory study. The ecological sig‘4ccepted February 8, 1966
NOTES
foot. These could, of course, also represent multicentric primary foci of infection. The epithelial covering of the foot terminated at the base of the polyp and was absent from its surface (Figs. 2, 3). In some sections the basement membrane of the epithelium could be seen over most of the growth. Essentially the same features described above were present in the smaller papilla on the edge of the foot, except that the surface projection was cone-shaped. Summarizing, these exophytic lesions on the foot of a gaper clam apparently represent exuberant inflammatory and reparative proc-
Pathogenicity
esses. They contain unclassified microorganisms that were either primary or secondary invaders. It would be of value to know whether similar lesions occur endemically in natural populations of this species, and if so, to learn the natural history of the disease. RONALD ALBERT
1 Approved for publication by the Director of the Wisconsin Agricultural Experiment Station. This work was supported in part by the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation, and in part by the U.S. Department of Agriculture, Forest Service Contract No. 12-11-012-560 (5).
C.
TAYLOR SMITH
Division of Biological Sciences University of California Irvine, California Accepted January
of Externally to Reticzditermes
Wood eaten by termites frequently shows evidence of fungal attack and termites are probably effective disseminators of fungus spores and hyphae. E. C. Hendee (Univ. CaZif. Pub. Zool., 39, 111-134, 1933) isolated representatives of 33 genera and 20 unidentified fungi from colonies of Reticulitermes hesperus, Kalotermes minor, and Zootermopsis angusticollis. The fungi were isolated from the guts, the exteriors of the termites, and from their tunnels. Marion Brooks (In E. A. Steinhaus, “Insect Pathology,” Academic Press Inc., New York, 1963) stated that externally borne fungi (of insects) are known poorly if at all. In the process of a much broader study, seven species of fungi were isolated externally from Reticulitermes fiavipes (Kol-
L.
Occurring jhipes’
2.5, 1966
Fungi
lar) and all were pathogenic under laboratory conditions. The fungi were identified by M. P. Backus, Department of Botany, University of Wisconsin, Madison, Wisconsin. Fifty termites, collected the same day in Janesville, Wisconsin, were chilled and shaken singly in vials of physiological saline which was then streaked over plates of malt agar and potato dextrose agar. Fungi were isolated from 15 termites only (30%). Plate cultures of the fungi were allowed to grow and sporulate for 2 weeks at which time 25 adult workers of R. flavipes were introduced to each culture. After 5 minutes the termites were removed from the cultures and incubated in closed circular plastic containers lined with moistened filter paper. For each group of 25 termites, 20 were incubated in one container and five were incubated singly. The results (Table 1) showed that the insects incubated singly suffered significantly greater mortality than those incubated in groups, except in those containers containing two species in the genus PenicilEium. With
267
NOTES
TABLE OF Reticulitermes
MORTALITY
OF SEVEN
flavijes
WHEN
EXTERNALLY
ISOLATED
Number
Fungi Gliomastix sp. Group of 20 5 (incubated singly) Cunninghamella echindata Group of 20 5 (incubated singly) Cephalosporium sp. Group of 20 5 (incubated singly) Paedomyces varioti, strain Group of 20 5 (incubated singly) Paecilomyces varioti, strain Group of 20 5 (incubated singly) Penicillium sp. (Asymmetrica Group of 20 5 (incubated singly) Penicillium oxalicurn Group of 20 5 (incubated singly) Penicillium freqentans Group of 20 5 (incubated singly)
TO SPORULATING FUNGUS
dead
PLATE
CULTURES
SPECIE@
at various (days)
intervals
1
2
4
6
Percent dead _-..-
0 0
0 0
0 3
2 3
10 60
2 4
2 5
4 5
4 5
20 100
1 0
1 0
1 3
1 4
5 X0
0 2
0 5
3 5
3 5
15 100
1 0
1 2
3 5
4 5
20 100
10 2
20 2
20 4
20 4
100 SO
5 2
20 2
20 2
20 3
100 60
0 0
0 0
4 2
4 3
20 60
0
0
0
0
0 ----
1
2
divaricata)
Check a The termites
1
EXPOSED
were incubated
both in groups
of 20 and singly.
these fungi the termites incubated in groups nificance of the pathogenicity reported herein were slightly more affected than those in- is not known. cubated singly. Considerable grooming acR. V. SMYTHE tivity was observed among the termites Wood Products Insect Lab. incubated in groups, and this probably ac- Box 2008 counted for much of the mortality difference Guljport, Mississippi beween the two modesof incubation. Though H. c. COPPEL R. flavipes apparently carries numerous funDepartment of Entomology gus spores externally on its body, it likely University of Wisconsin never or rarely encounters a concentration Madison, Wisconsin of sporesin nature similar to that provided in the laboratory study. The ecological sig‘4ccepted February 8, 1966