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Melanotic encapsulation of the nematode Neoaplectana carpocapsae by Aedes aegypti larvae concurrently parasitized by the nematode Reesimermis nielseni
JOURNAL
OF
INVERTEBRATE
PATHOLOGY
Melanotic
26,269-270
(1975)
Encapsulation
of the Nematode
Neoaplectana carpocapsae by Aedes Parasitized by the Nematode Both mosquitoes and chironomid midges react to a number of metazoan parasites by forming a capsule around them (J.F. Bronskill, Can. J. Zool. 40, 1269-1275, 1962; P. Gijtz, Zool. Anz. (Suppl.) Verh. Zool. Ges. 33, 610-617, 1969). These capsules are noncellular and appear to be composed primarily of melanin (G. 0. Poinar and R. Leutenegger, J. Ultrastruct. Res. 36, 149158, 1971). P. Giitz and A. Vey (Purasitology 68, 193-205, 1974) have suggested that the capsules are formed as the result of activation of hemolymph phenoloxidases. Many, if not all, species of mosquitoes, including Aedes aegypti, are capable of encapsulating Neoaplectana carpocapsae (H. E. Welch and J. F. Bronskill, Can. J. Zool. 40, 1263-1268, 1962; D. W. Hall, unpub.). In contrast, only a few species have been found to encapsulate the mermithid Reesimermis nielseni (J. J. Petersen, H. C. Chapman, and 0. R. Willis, Mosq. News 29,198-201,1969) and A. aegypti never does so. The manner in which certain parasites escape the immune responses of their invertebrate hosts is a fascinating problem. There is evidence that the parasitic wasps Apan teles glomeratus and Pseudeucoila bochei are capable of active suppression of the encapsulation reactions of their natural hosts (H. Kitano, J. Insect Physiol. 20, 315 327, 1974; A. J. Nappi and F. A. Streams, J. Insect Physiol. 15, 1551-1566, 1969; F. A. Streams and L. Greenberg, J. Znvertebr. Pathol. 13, 371-377, 1969; I. Walker, Rev. ‘Paper periment Amherst. periment
No. 1020, Massachusetts Agricultural Station, University of Massachusetts This research supported (in part) from Station Project No. 322.
Copyright All rights
$1 1975 by Academic Press, Inc. of reproduction in any form reserved.
Exat Ex-
aegypti Larvae Concurrently Reesimermis nielseni ’
Suisse Zool. 66, 569-632,
1959). The purpose of the present study was to determine whether or not R. nielseni is capable of suppressing the encapsulation reaction of A. thereby protecting N. aegyp ti and carpocapsae from encapsulation. Two-hundred 48-hr-old A. aegypti larvae were exposed to infective-stage R. nielseni at a ratio of 20 nematodes to each larva. After reaching the 4th instar, these larvae were exposed to large numbers of infective-stage N. carpocapsae for a period of 3 hr, rinsed, held for 5 hr to allow ample time for complete encapsulation, and dissected. A total of 81 larvae were parasitized by both R. nielseni and N. carpocapsae. Seventy-five of these were still capable of encapsulating N. carpocapsae. Many of these larvae contained more than one R. nielseni, and one larvae contained seven. Histological sections of capsules surrounding N. carpocapsae . appeared to be identical regardless of whether R. nielseni was present or not. R. nielseni was never encapsulated even in larvae in which the reaction was initiated against N. carpocupsae (Fig. 1). Two conclusions may be drawn from these results. First, the fact that N. was encapsulated in the carpocapsae presence of R. nielseni suggests that R. nielseni does not actively suppress the encapsulation reaction unless the supression is affected locally at the surface of the cuticle. Of perhaps greater significance is the fact that even after the encapsulation reaction is activated by N. carpocapsae, R. nielseni is still not encapsulated, which indicates that specificity of the reaction resides not only in the activation step but also in the actual de-
269
NOTES
270
FIG. I Aedes aegypri larva with Reesimermis
nielseni
position of the capsular material. The basis for the specificity of this type of reaction poses an intriguing problem for future research. DONALD W. HALLS 2Present Nematology, Gainesville,
address: Department McCarty Hall, Florida 326 I I.
of Entomology and University of Florida,
(R) and encapsulated
Neoaplectana
carpocapsae
(N).
THEODORE G. ANDREADIS THOMAS R. FLANAGAN WALTER J. KACZOR
Department of Entomology University of Massachusetts Amherst, Massachusetts 01002 Received August 21,1974
OF
INVERTEBRATE
PATHOLOGY
Melanotic
26,269-270
(1975)
Encapsulation
of the Nematode
Neoaplectana carpocapsae by Aedes Parasitized by the Nematode Both mosquitoes and chironomid midges react to a number of metazoan parasites by forming a capsule around them (J.F. Bronskill, Can. J. Zool. 40, 1269-1275, 1962; P. Gijtz, Zool. Anz. (Suppl.) Verh. Zool. Ges. 33, 610-617, 1969). These capsules are noncellular and appear to be composed primarily of melanin (G. 0. Poinar and R. Leutenegger, J. Ultrastruct. Res. 36, 149158, 1971). P. Giitz and A. Vey (Purasitology 68, 193-205, 1974) have suggested that the capsules are formed as the result of activation of hemolymph phenoloxidases. Many, if not all, species of mosquitoes, including Aedes aegypti, are capable of encapsulating Neoaplectana carpocapsae (H. E. Welch and J. F. Bronskill, Can. J. Zool. 40, 1263-1268, 1962; D. W. Hall, unpub.). In contrast, only a few species have been found to encapsulate the mermithid Reesimermis nielseni (J. J. Petersen, H. C. Chapman, and 0. R. Willis, Mosq. News 29,198-201,1969) and A. aegypti never does so. The manner in which certain parasites escape the immune responses of their invertebrate hosts is a fascinating problem. There is evidence that the parasitic wasps Apan teles glomeratus and Pseudeucoila bochei are capable of active suppression of the encapsulation reactions of their natural hosts (H. Kitano, J. Insect Physiol. 20, 315 327, 1974; A. J. Nappi and F. A. Streams, J. Insect Physiol. 15, 1551-1566, 1969; F. A. Streams and L. Greenberg, J. Znvertebr. Pathol. 13, 371-377, 1969; I. Walker, Rev. ‘Paper periment Amherst. periment
No. 1020, Massachusetts Agricultural Station, University of Massachusetts This research supported (in part) from Station Project No. 322.
Copyright All rights
$1 1975 by Academic Press, Inc. of reproduction in any form reserved.
Exat Ex-
aegypti Larvae Concurrently Reesimermis nielseni ’
Suisse Zool. 66, 569-632,
1959). The purpose of the present study was to determine whether or not R. nielseni is capable of suppressing the encapsulation reaction of A. thereby protecting N. aegyp ti and carpocapsae from encapsulation. Two-hundred 48-hr-old A. aegypti larvae were exposed to infective-stage R. nielseni at a ratio of 20 nematodes to each larva. After reaching the 4th instar, these larvae were exposed to large numbers of infective-stage N. carpocapsae for a period of 3 hr, rinsed, held for 5 hr to allow ample time for complete encapsulation, and dissected. A total of 81 larvae were parasitized by both R. nielseni and N. carpocapsae. Seventy-five of these were still capable of encapsulating N. carpocapsae. Many of these larvae contained more than one R. nielseni, and one larvae contained seven. Histological sections of capsules surrounding N. carpocapsae . appeared to be identical regardless of whether R. nielseni was present or not. R. nielseni was never encapsulated even in larvae in which the reaction was initiated against N. carpocupsae (Fig. 1). Two conclusions may be drawn from these results. First, the fact that N. was encapsulated in the carpocapsae presence of R. nielseni suggests that R. nielseni does not actively suppress the encapsulation reaction unless the supression is affected locally at the surface of the cuticle. Of perhaps greater significance is the fact that even after the encapsulation reaction is activated by N. carpocapsae, R. nielseni is still not encapsulated, which indicates that specificity of the reaction resides not only in the activation step but also in the actual de-
269
NOTES
270
FIG. I Aedes aegypri larva with Reesimermis
nielseni
position of the capsular material. The basis for the specificity of this type of reaction poses an intriguing problem for future research. DONALD W. HALLS 2Present Nematology, Gainesville,
address: Department McCarty Hall, Florida 326 I I.
of Entomology and University of Florida,
(R) and encapsulated
Neoaplectana
carpocapsae
(N).
THEODORE G. ANDREADIS THOMAS R. FLANAGAN WALTER J. KACZOR
Department of Entomology University of Massachusetts Amherst, Massachusetts 01002 Received August 21,1974