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Host-pathogen relationships of two previously undescribed microsporidia from the Indian-meal moth, Plodia interpunctella (Hübner), (Lepidoptera: Phycitidae)
JOURNAL
OF INVERTEBRATE
PATHOLOGY
14, 328-335
(1969)
Host-Pathogen Relationships of Two Previously Undescribed Microsporidia from the Indian-Meal Moth, Plod&z interpunctellu (Hiibner), (Lepidoptera: Phycitidae) WILLIAM
R. KELLEN
AND JAMES
E. LINDEGREN
Stored-Pro&d Insects Research Branch, Market Quality Research Agricultural Research Service, US Department of Agriculture, Fresno, California 93727 ReceLcetl
March
Id.
Division,
1969
Moribund larvae of the Indian-meal moth, Plodia interpunctella ( Hiibner ), collected in California harbored dual infections of two previously undescribed species of Microsporidia, Nosema heterosporum sp. n. and Thelohania nana sp. n. N. heterosporum is highly infective and was readily transmitted perorally to larvae in laboratory tests; such infections were usually progressive. Transovarian transmission did not occur. Midgut epithelium and fat tissue are primarily invaded; silk and salivary glands and muscle are invaded to a re!atively light degree. Spores are morphologically variable and may remain viable for at least a year at 4°C in aqueous suspension. T. nana primarily invades fat tissue and occasionally occurs in muscle. It was readily transmitted to young larvae, but it has only been observed in dual infections. The thelohanian may occur independently in isolated fat lobes adjacent to tissue harboring Nosema. Both microsporidians were transmitted to the navel orangeworm, Paramyelois transitella ( Walker), and the greater wax moth, Galleria mellonella ( Linneaus ). The almond moth, Cadra cautella Walker, the raisin moth, Cadra figulilella Gregson, the tobacco moth, Ephestia elutclla ( Hiibner ), the confused flour beetle, Tribolium confmum Jacquelin duval, and the dried fruit beetle, Carpoplrihrs hemiptelns ( Linnaeus), were not susceptible in laboratory tests.
INTRODUCTION
The only species of Microsporidia previously described from the Indian-meal moth, Plodia interpunctella ( Hiibner ), is Nosema plodiae Kellen and Lindegren ( 1968) which was described from diseased adult moths originally collected from infested dried figs in Fresno, California. Subsequent examination of additional larvae of the Indian-meal moth collected on dried prunes from California has disclosed a second species of Nosema and an undescribed species of Thelohania. Because of the economic importance of this moth as a pest of storedproducts, and the lack of information of its associated pathogens, this study was conducted to establish the identity and the de-
scriptive diagnostic characteristics of the microsporidians and to clarify host-pathogen relationships. MATERIALS
AND
METHODS
During November, 1966, about 50 diseased larvae of the Indian-meal moth were collected from infested prunes obtained from Sacramento, California. The dried fruit had been intentionally exposed in the field for several months to attract insects which were to be examined for pathogens. Moribund larvae from this collection were dissected in 0.65% saline, and exposed tissues were examined at a magnification of 20 diameters. Particular attention was given to the detection of signs of infection in silk and
MI’ZROSPORIDIA
FROM
salivary glands, Malpighian tubes, and fat tissue. Opaque or hytertrophied tissues were excised, squashed in saline mounts, and examined with a phase contrast microscope at a magnification of 1000 diameters to confirm the presence of pathogens. Dried cadavers of larvae and pupae containing microsporidian spores were triturated in saline and added to a rearing medium described by Finney and Brinkman ( 1967); the contaminated medium was fed to young larvae from a laboratory culture. Test larvae readily acquired infections perorally and usually developed signs and symptoms of microsporidiosis after about l-2 weeks. Additional larvae harboring mature spores were subsequently used to infect laboratory cultures of P. interpunctella for histological studies, Techniques and materials used to determine the stages in the life cycles of the microsporidians and certain host-pathogen relationships were similar to those reported in an earlier paper (Kellen and Lindegren, 1968 ) . The new species of Thelohunia has onlv been observed in dual infections with Ndsema. Since most infected fat bodies harbored a mixture of stages in the development of both microsporidians, it was difficult to obtain stained preparations which were exclusively of T. nana. Several uncontaminated preparations were made, however, from isolated fat lobes. Host susceptibility tests were conducted with laboratory strains of Paramyelois transitellu, Cadra cazrtella, Cadra figulillelu, Ephestia elutella, Galleria mellonella, Tribolium confustm, and Carpophihcs hemipterus. SYSTEMATICS
Holotype slides of the new species have been deposited in the type collection of the US. National Museum. Paratype slides have been deposited in the collections of J. J. Lipa, Laboratory of Biological Control, In-
INDIAN-MEAL
329
MOTH
stitute of Plant Protection, Poznan, Poland; J. Weiser, Department of Insect Pathology, Institute of Biology, Czechoslovakian Academy of Sciences, Prague; J. P. Kramer, Department of Entomology and Limnology, Cornell University, Ithaca, New York; and in the collection of the authors. Nosemu heterosporum sp. n. (Figs. l-83) Derivation of Name: A Nosema having dissimilar spores. Host: All stages of Plodia interpunctellu. Primarily invades wall of the midgut and fat bodies; to a lesser extent invades silk and salivary glands forming characteristic nodules (Figs. 79-83); invades muscle infrequently. Also transmitted to Galbria mellon&la and Paramyelois transitella in the laboratory. Morphology: Fresh material. Mature spores, 5.46 11* 0.65 u X 1.99 u t 0.03 u (n = 50). Polar filament, 110 u-165 8~long when extruded under pressure. Relative few filaments are extruded from fresh spores that are allowed to dry under a cover glass. Stained material (Giemsa) fixed with methyl alcohol. Mature spores, 4.95 u + 0.09 u X 2.08 u * 0.01 u (n = 50). Diameter of mononucleate schizont, 2 u-3 u; quadrinucleate schizont, 4 u-6 ~1; 16-nucleate schizont, approx. 16 u; “chainschizonts” having 4-10 nuclei, approx. 40 u long; young sporoblasts, 6 u X 3 u; aberrant sporonts with 4-8 ring-shaped nuclei, approx. 20 u X 4 u; mature macrospores to approx. 16 p X 3.5 p. Locality Record: Sacramento, California. Type Material: Holotype slide, X14-66, Sacramento, California. U.S.N.M. Helm. No. 60693. Paratype slides prepared from laboratory infected larvae, Fresno, California, VII-27-68, VIII-20-1968. LIFE
CYCLE
AND
BIOLOGY
Although we examined excised midguts in saline mounts made at intervals up to 1 hr
FIGS. l-40. with dark-staining modium. 16-34.
Developmental stages of Nosema heterosporum sp. n. Giemsa-stained: compact nuclei. 7-14. Multinucleate schizonts with ring-nuclei. 15. Typical schizonts with distinct nuclear configurations. 35-40. Sporonts. 330
1-6.
Schizonts
Budding
plas-
MICROSPORIDIA FROM INDIAN-MEAL MOTH
Ifi 62
“60
6’
6y64’
(
)
66’
n
FIGS. 41-74. Developmental stages of Nosema heterosporum sp. n. Giemsa-stained: 41-51. Aberrant sporonts leading to development of macrospores. 52-55. Typical sporoblasts. 56. Young spore. 5758. Macrospore and typical spore, respectively, stained by Feulgen’s method. 59-65. Fresh macrospores. 66-73. Fresh typical spores. 74. Polar filament extruded with pressure.
332
KELLEN
AND
LINDEGREN
F1cs.75~83. Comparison of silk and salivary glands of patently infected Plodia interpunctella. mounts: 75, 76 and 77, 78. Silk and salivary glands, respectively, invaded by Nosema plodiae. and 81-83. Silk and salivary glands, respectively, invaded by N. Jzetero.yporum, showing typically extent of invasion and hypertrophy.
Saline
79, 80 limited
MICROSPORIDIA
FROM
after spore ingestion, we were unsuccessful in attempts to witness the extrusion of filaments and the escape of sporoplasms. Stained smears of midguts made as early as one-half hour after spore ingestion (T = 27”C), however, usually contained a few mono- and binucleate trophozoites about 2-4 ~1in diameter ( Figs. 1 and 2). There was a considerable increase in the number of such stages 24 hr after initial infection, and by 48 hr stages of schizogony were abundant in the gut wall (Figs. 3-34). Sporoblasts were present in smears made 3 days after initial invasion, and severe damage to the gut wall was frequently evident. The normal elasticity of the organ was lost, the gut wall was easily ruptured during dissection, and cells readily sloughed off. After heavy invasion of the gut, infection usually spread to adjacent fat tissue. Muscle, silk, and salivary glands were invaded less frequently. The formation of aberrant sporonts and sporoblasts occurred commonly (Figs. 4351). Such forms were usually present in smears of fat tissue from moribund larvae, and gave rise to macrospores having 4-8 nuclei (Figs. 57, 59-65). The presence and characteristic appearance of the macrospores were valuable aids for diagnosing this pathogen. Similarly, the characteristically limited degree of invasion of silk and salivary glands and the formation of conspicuous nodules on the glands provided a simple macroscopic means for diagnosing infections by N. heterosporum (Figs. 7583). In contrast, N. pZodiae typically invades throughout the entire length of the glands, giving the normally transparent glands a cloudy white appearance; localized hypertrophy does not occur. Silk and salivary glands of larvae harboring dual infections of these two species of Nosema develop both characteristics. Larvae of P. interpunctella which were containing maintained on a medium 5 X lo4 spores per gram usually became moribund within 10 davs in laboratory tests
INDIAN-MEAL
MOTH
333
(T = 27°C). Reproductive organs of a few individuals that survived to the adult stage in our tests were not invaded, and transovarian transmission did not occur. This was in contrast to our observations of N. plodiae, which is commonly transmitted transovarially. Rehydration of dried spores did not cause extrusion of polar filaments; similarly, the application of macerated midguts, salivary glands, or regurgitated gut juice to fresh spores produced no apparent effect. Filaments were, however, readily extruded by applying pressure to microslide preparations. When such preparations were stained with Giemsa’s solution, they demonstrated the progressive movement of a binucleate sporoplasm through the length of the filament, similar to that reported by Kramer ( 1960). When passing through the filament, each of the twin nuclei measured about 8~ long and they were separated by a space of l-10 n. In the key to the speciesof Microsporidia described from Lepidoptera which was devised by Weiser ( 1961), Nosema heterosporum is accommodated in the cuplet which segregates Nosema nzesnili ( Paillot), Nosema aporivora Veber, and N. brassicae ( Paillot). Nosema heterosporum is easily distinguished from these specieson the basis of spore morphology and tissue specificity. Thelohaniu nana sp. n. (Figs. 84-102) Derivation of Name: A dwarf Thelohania, for the small size of the spores. Host: All stages of Plodia interpunctella. Primarily invades fat tissue, invades muscle infrequently. Does not invade silk or salivary glands. Also transmitted to P. transitella in laboratory. Morphology: Fresh material. Mature spores, 2.07 p + 0.03 11X 1.86 ~1t 0.02 u (n = 50); macrospores measure up to about 3.5 p X 2.25 u. Polar filament, appro”. 80 p long. Stained material (Giemsa) fixed with
334
FIos. 84-102. 88-97. Sporonts. spores,
KELLEN
AND
LINDEGREN
Developmental stages of Thelohznia 98. Typical group of 8 spores. 99-102.
nana sp. Aberrant
n. Giemsa-stained: groups of spores,
84-87. Schizonts. including macro-
methyl alcohol. Mature spores, 2.27 u ? first observed to occur in fat tissue smears 0.02 u X 1.60 p 2 0.01 (n = 50); groups of that were made 20 days after larvae were 8 spores (diameter), 5.76 u r+ 0.05. Monoprovided contaminated food (T = 27°C). and binucleate trophozoites, 3.5 u X 2.0 u; This pathogen has only been observed in various sporogonic stages and pansporodual infections with N. plodiae and N. blasts, approx. 5 u-7 p. heterosporum. Usually Nosema dominates Locality Records: Fresno, California, such dual infections, however, sections of VIII-17-66; Sacramento, California, X14patently diseased larvae show that occa66. sionally the Thelohania may predominate. Type Material: Holotype slide, SacraIndividual lobes of fat frequently harbored mento, California, X1-4-66. U.S.N.M. Helm. T. nanu exclusively, although adjacent lobes No. 60694. were infected with Nosema. We have made T. nuna typically forms groups of 8 a few attempts to transmit T. nana indepenspores; however, groups of variable numdently to larvae of P. interpunctellu, but bers of spores, ranging from 2-6 and in- they were unsuccessful. This pathogen also cluding macrospores, were frequently ob- invades P. transitella and G. mellonella. In served (Figs. 99-102). The generation time Weiser’s key ( 1961)) Thelohaniu nana is of this species is relatively long. Spores were included in the cuplet which isolates Thelo-
MICROSPORIDIA
FROM
hania cheimatobiae Krieg, but differences readily segregate in spore morphology these two species. REFERENCES G. L., AND BRINKMAN, D. 1967. Rearing the navel orangeworm in the laboratory. J. Econ. Entomol., 60, 1109-1111. KELLEK, W. R., AXD LINDEGREN, J. E. 1968. Bi-
FINNEY,
INDIAN-MEAL
MOTH
335
ology of Nosema plodiae sp. n., a microsporidian pathogen of the Indian-meal moth, Plodia interpunctella ( Hiibner ) , ( Lepidoptera:Phycitidae). J. Invertebrate Pathol., 11, 104-111. KRAMER, J. P. 1960. Observations on the emergence of the microsporidian sporoplasm. J. Insect Pathol., 2, 433439. WEISER, JAROSLAV 1961. “Die Mikrosporidien als Parasiten der Insekten,” Monograph. zur Angew. Entomol., No. 17, 149 pp.
OF INVERTEBRATE
PATHOLOGY
14, 328-335
(1969)
Host-Pathogen Relationships of Two Previously Undescribed Microsporidia from the Indian-Meal Moth, Plod&z interpunctellu (Hiibner), (Lepidoptera: Phycitidae) WILLIAM
R. KELLEN
AND JAMES
E. LINDEGREN
Stored-Pro&d Insects Research Branch, Market Quality Research Agricultural Research Service, US Department of Agriculture, Fresno, California 93727 ReceLcetl
March
Id.
Division,
1969
Moribund larvae of the Indian-meal moth, Plodia interpunctella ( Hiibner ), collected in California harbored dual infections of two previously undescribed species of Microsporidia, Nosema heterosporum sp. n. and Thelohania nana sp. n. N. heterosporum is highly infective and was readily transmitted perorally to larvae in laboratory tests; such infections were usually progressive. Transovarian transmission did not occur. Midgut epithelium and fat tissue are primarily invaded; silk and salivary glands and muscle are invaded to a re!atively light degree. Spores are morphologically variable and may remain viable for at least a year at 4°C in aqueous suspension. T. nana primarily invades fat tissue and occasionally occurs in muscle. It was readily transmitted to young larvae, but it has only been observed in dual infections. The thelohanian may occur independently in isolated fat lobes adjacent to tissue harboring Nosema. Both microsporidians were transmitted to the navel orangeworm, Paramyelois transitella ( Walker), and the greater wax moth, Galleria mellonella ( Linneaus ). The almond moth, Cadra cautella Walker, the raisin moth, Cadra figulilella Gregson, the tobacco moth, Ephestia elutclla ( Hiibner ), the confused flour beetle, Tribolium confmum Jacquelin duval, and the dried fruit beetle, Carpoplrihrs hemiptelns ( Linnaeus), were not susceptible in laboratory tests.
INTRODUCTION
The only species of Microsporidia previously described from the Indian-meal moth, Plodia interpunctella ( Hiibner ), is Nosema plodiae Kellen and Lindegren ( 1968) which was described from diseased adult moths originally collected from infested dried figs in Fresno, California. Subsequent examination of additional larvae of the Indian-meal moth collected on dried prunes from California has disclosed a second species of Nosema and an undescribed species of Thelohania. Because of the economic importance of this moth as a pest of storedproducts, and the lack of information of its associated pathogens, this study was conducted to establish the identity and the de-
scriptive diagnostic characteristics of the microsporidians and to clarify host-pathogen relationships. MATERIALS
AND
METHODS
During November, 1966, about 50 diseased larvae of the Indian-meal moth were collected from infested prunes obtained from Sacramento, California. The dried fruit had been intentionally exposed in the field for several months to attract insects which were to be examined for pathogens. Moribund larvae from this collection were dissected in 0.65% saline, and exposed tissues were examined at a magnification of 20 diameters. Particular attention was given to the detection of signs of infection in silk and
MI’ZROSPORIDIA
FROM
salivary glands, Malpighian tubes, and fat tissue. Opaque or hytertrophied tissues were excised, squashed in saline mounts, and examined with a phase contrast microscope at a magnification of 1000 diameters to confirm the presence of pathogens. Dried cadavers of larvae and pupae containing microsporidian spores were triturated in saline and added to a rearing medium described by Finney and Brinkman ( 1967); the contaminated medium was fed to young larvae from a laboratory culture. Test larvae readily acquired infections perorally and usually developed signs and symptoms of microsporidiosis after about l-2 weeks. Additional larvae harboring mature spores were subsequently used to infect laboratory cultures of P. interpunctella for histological studies, Techniques and materials used to determine the stages in the life cycles of the microsporidians and certain host-pathogen relationships were similar to those reported in an earlier paper (Kellen and Lindegren, 1968 ) . The new species of Thelohunia has onlv been observed in dual infections with Ndsema. Since most infected fat bodies harbored a mixture of stages in the development of both microsporidians, it was difficult to obtain stained preparations which were exclusively of T. nana. Several uncontaminated preparations were made, however, from isolated fat lobes. Host susceptibility tests were conducted with laboratory strains of Paramyelois transitellu, Cadra cazrtella, Cadra figulillelu, Ephestia elutella, Galleria mellonella, Tribolium confustm, and Carpophihcs hemipterus. SYSTEMATICS
Holotype slides of the new species have been deposited in the type collection of the US. National Museum. Paratype slides have been deposited in the collections of J. J. Lipa, Laboratory of Biological Control, In-
INDIAN-MEAL
329
MOTH
stitute of Plant Protection, Poznan, Poland; J. Weiser, Department of Insect Pathology, Institute of Biology, Czechoslovakian Academy of Sciences, Prague; J. P. Kramer, Department of Entomology and Limnology, Cornell University, Ithaca, New York; and in the collection of the authors. Nosemu heterosporum sp. n. (Figs. l-83) Derivation of Name: A Nosema having dissimilar spores. Host: All stages of Plodia interpunctellu. Primarily invades wall of the midgut and fat bodies; to a lesser extent invades silk and salivary glands forming characteristic nodules (Figs. 79-83); invades muscle infrequently. Also transmitted to Galbria mellon&la and Paramyelois transitella in the laboratory. Morphology: Fresh material. Mature spores, 5.46 11* 0.65 u X 1.99 u t 0.03 u (n = 50). Polar filament, 110 u-165 8~long when extruded under pressure. Relative few filaments are extruded from fresh spores that are allowed to dry under a cover glass. Stained material (Giemsa) fixed with methyl alcohol. Mature spores, 4.95 u + 0.09 u X 2.08 u * 0.01 u (n = 50). Diameter of mononucleate schizont, 2 u-3 u; quadrinucleate schizont, 4 u-6 ~1; 16-nucleate schizont, approx. 16 u; “chainschizonts” having 4-10 nuclei, approx. 40 u long; young sporoblasts, 6 u X 3 u; aberrant sporonts with 4-8 ring-shaped nuclei, approx. 20 u X 4 u; mature macrospores to approx. 16 p X 3.5 p. Locality Record: Sacramento, California. Type Material: Holotype slide, X14-66, Sacramento, California. U.S.N.M. Helm. No. 60693. Paratype slides prepared from laboratory infected larvae, Fresno, California, VII-27-68, VIII-20-1968. LIFE
CYCLE
AND
BIOLOGY
Although we examined excised midguts in saline mounts made at intervals up to 1 hr
FIGS. l-40. with dark-staining modium. 16-34.
Developmental stages of Nosema heterosporum sp. n. Giemsa-stained: compact nuclei. 7-14. Multinucleate schizonts with ring-nuclei. 15. Typical schizonts with distinct nuclear configurations. 35-40. Sporonts. 330
1-6.
Schizonts
Budding
plas-
MICROSPORIDIA FROM INDIAN-MEAL MOTH
Ifi 62
“60
6’
6y64’
(
)
66’
n
FIGS. 41-74. Developmental stages of Nosema heterosporum sp. n. Giemsa-stained: 41-51. Aberrant sporonts leading to development of macrospores. 52-55. Typical sporoblasts. 56. Young spore. 5758. Macrospore and typical spore, respectively, stained by Feulgen’s method. 59-65. Fresh macrospores. 66-73. Fresh typical spores. 74. Polar filament extruded with pressure.
332
KELLEN
AND
LINDEGREN
F1cs.75~83. Comparison of silk and salivary glands of patently infected Plodia interpunctella. mounts: 75, 76 and 77, 78. Silk and salivary glands, respectively, invaded by Nosema plodiae. and 81-83. Silk and salivary glands, respectively, invaded by N. Jzetero.yporum, showing typically extent of invasion and hypertrophy.
Saline
79, 80 limited
MICROSPORIDIA
FROM
after spore ingestion, we were unsuccessful in attempts to witness the extrusion of filaments and the escape of sporoplasms. Stained smears of midguts made as early as one-half hour after spore ingestion (T = 27”C), however, usually contained a few mono- and binucleate trophozoites about 2-4 ~1in diameter ( Figs. 1 and 2). There was a considerable increase in the number of such stages 24 hr after initial infection, and by 48 hr stages of schizogony were abundant in the gut wall (Figs. 3-34). Sporoblasts were present in smears made 3 days after initial invasion, and severe damage to the gut wall was frequently evident. The normal elasticity of the organ was lost, the gut wall was easily ruptured during dissection, and cells readily sloughed off. After heavy invasion of the gut, infection usually spread to adjacent fat tissue. Muscle, silk, and salivary glands were invaded less frequently. The formation of aberrant sporonts and sporoblasts occurred commonly (Figs. 4351). Such forms were usually present in smears of fat tissue from moribund larvae, and gave rise to macrospores having 4-8 nuclei (Figs. 57, 59-65). The presence and characteristic appearance of the macrospores were valuable aids for diagnosing this pathogen. Similarly, the characteristically limited degree of invasion of silk and salivary glands and the formation of conspicuous nodules on the glands provided a simple macroscopic means for diagnosing infections by N. heterosporum (Figs. 7583). In contrast, N. pZodiae typically invades throughout the entire length of the glands, giving the normally transparent glands a cloudy white appearance; localized hypertrophy does not occur. Silk and salivary glands of larvae harboring dual infections of these two species of Nosema develop both characteristics. Larvae of P. interpunctella which were containing maintained on a medium 5 X lo4 spores per gram usually became moribund within 10 davs in laboratory tests
INDIAN-MEAL
MOTH
333
(T = 27°C). Reproductive organs of a few individuals that survived to the adult stage in our tests were not invaded, and transovarian transmission did not occur. This was in contrast to our observations of N. plodiae, which is commonly transmitted transovarially. Rehydration of dried spores did not cause extrusion of polar filaments; similarly, the application of macerated midguts, salivary glands, or regurgitated gut juice to fresh spores produced no apparent effect. Filaments were, however, readily extruded by applying pressure to microslide preparations. When such preparations were stained with Giemsa’s solution, they demonstrated the progressive movement of a binucleate sporoplasm through the length of the filament, similar to that reported by Kramer ( 1960). When passing through the filament, each of the twin nuclei measured about 8~ long and they were separated by a space of l-10 n. In the key to the speciesof Microsporidia described from Lepidoptera which was devised by Weiser ( 1961), Nosema heterosporum is accommodated in the cuplet which segregates Nosema nzesnili ( Paillot), Nosema aporivora Veber, and N. brassicae ( Paillot). Nosema heterosporum is easily distinguished from these specieson the basis of spore morphology and tissue specificity. Thelohaniu nana sp. n. (Figs. 84-102) Derivation of Name: A dwarf Thelohania, for the small size of the spores. Host: All stages of Plodia interpunctella. Primarily invades fat tissue, invades muscle infrequently. Does not invade silk or salivary glands. Also transmitted to P. transitella in laboratory. Morphology: Fresh material. Mature spores, 2.07 p + 0.03 11X 1.86 ~1t 0.02 u (n = 50); macrospores measure up to about 3.5 p X 2.25 u. Polar filament, appro”. 80 p long. Stained material (Giemsa) fixed with
334
FIos. 84-102. 88-97. Sporonts. spores,
KELLEN
AND
LINDEGREN
Developmental stages of Thelohznia 98. Typical group of 8 spores. 99-102.
nana sp. Aberrant
n. Giemsa-stained: groups of spores,
84-87. Schizonts. including macro-
methyl alcohol. Mature spores, 2.27 u ? first observed to occur in fat tissue smears 0.02 u X 1.60 p 2 0.01 (n = 50); groups of that were made 20 days after larvae were 8 spores (diameter), 5.76 u r+ 0.05. Monoprovided contaminated food (T = 27°C). and binucleate trophozoites, 3.5 u X 2.0 u; This pathogen has only been observed in various sporogonic stages and pansporodual infections with N. plodiae and N. blasts, approx. 5 u-7 p. heterosporum. Usually Nosema dominates Locality Records: Fresno, California, such dual infections, however, sections of VIII-17-66; Sacramento, California, X14patently diseased larvae show that occa66. sionally the Thelohania may predominate. Type Material: Holotype slide, SacraIndividual lobes of fat frequently harbored mento, California, X1-4-66. U.S.N.M. Helm. T. nanu exclusively, although adjacent lobes No. 60694. were infected with Nosema. We have made T. nuna typically forms groups of 8 a few attempts to transmit T. nana indepenspores; however, groups of variable numdently to larvae of P. interpunctellu, but bers of spores, ranging from 2-6 and in- they were unsuccessful. This pathogen also cluding macrospores, were frequently ob- invades P. transitella and G. mellonella. In served (Figs. 99-102). The generation time Weiser’s key ( 1961)) Thelohaniu nana is of this species is relatively long. Spores were included in the cuplet which isolates Thelo-
MICROSPORIDIA
FROM
hania cheimatobiae Krieg, but differences readily segregate in spore morphology these two species. REFERENCES G. L., AND BRINKMAN, D. 1967. Rearing the navel orangeworm in the laboratory. J. Econ. Entomol., 60, 1109-1111. KELLEK, W. R., AXD LINDEGREN, J. E. 1968. Bi-
FINNEY,
INDIAN-MEAL
MOTH
335
ology of Nosema plodiae sp. n., a microsporidian pathogen of the Indian-meal moth, Plodia interpunctella ( Hiibner ) , ( Lepidoptera:Phycitidae). J. Invertebrate Pathol., 11, 104-111. KRAMER, J. P. 1960. Observations on the emergence of the microsporidian sporoplasm. J. Insect Pathol., 2, 433439. WEISER, JAROSLAV 1961. “Die Mikrosporidien als Parasiten der Insekten,” Monograph. zur Angew. Entomol., No. 17, 149 pp.