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Rearing larvae of Leptoconops bequaerti Kieffer (Diptera: Ceratopogonidae) in the field
LABORATORY
MEETING
21
Mr. F. A. S. K u z o e , Mr. J. J. B. Gill a n d D r . W. W. M a c d o n a l d
Liverpool School of Tropical Medicine E v i d e n c e o f i n v e r s i o n s in the c h r o m o s o m e s Culex
in the testes o f Aedes aegypti a n d
pipiens fatigans
Squash preparations of the testes from pupae of Aedes aegypti and Culex pipiens I n both species there are 3 pairs of chromosomes and the preparations, stained with aceto-orcein, showed different stages of meiosis. I n one preparation of Ae. aegypti the three pairs of chromosomes showed 2, 3 and 4 chiasmata respectively at prophase I. Other preparations showed metaphase I, anaphase I and telophase I chromosomes and chromosome fragments. I n C. p. fatigans similar fragments were present in a preparation of anaphase I chromosomes. Chromosome fragments have been observed in 5 of 278 Ae. aegypti pupae and in 2 of 102 C. p. fatigans pupae. T h e fragments have been interpreted as the result of crossingover within inversions in the chromosomes.
fatigans were demonstrated.
Mr. A. K i r k w o o d
Central Veterinary Laboratory, Weybridge Some mites associated with poultry I n the course of a survey of mites on 2,497 chickens submitted for post-mortem examination the following mites were found: Dermanyssus gallinae, Liponyssus sylviarum,
Cnemidocoptes mutans, Syringophilus bipectinatus, Macrocheles matrius, Haemolaelaps casalis, and Acarus siro. These mites were demonstrated. Mr. J. L i u l e y
London School of Hygiene and Tropical Medicine R e a r i n g l a r v a e o f Leptoconops bequaerti Kieffer (Diptera: C e r a t o p o g o n i d a e ) i n t h e field
Leptoconops bequaerti is a small biting midge which occurs in Jamaica and other areas in the Caribbean. It is important because it presents a threat to the frequently enormous investments made in promoting tourism in the island. I n fact, L. bequaerti has a particular significance in this respect, since it may breed in white sand beaches, which are suitable for tourist development, and since the females bite throughout the day in quite strong winds when the majority of visitors wish to use the beaches. Attempts to gain an understanding of larval biology in L. bequaerti were complicated by the fact that larvae could not be reared with any success in the laboratory. 3 traps were therefore designed in which larvae could be reared in the field. T h e construction of these traps, and their methods of use, were illustrated by diagrams and photographs. The function of all three designs was to aUow larvae of known origin to develop on the natural breeding sites, but in an environment isolated from any "wild" larvae present on the chosen site. Information was gathered on a variety of topics connected with larval biology. Some of these were: (1) the duration of the larval stage under various conditions, (2) larval survival, (3) effect of larval environment on the size of resulting adults, (4) the sex ratio, (5) the sequence of adult emergence. D r . B. R. L a u r e n c e
London School of Hygiene and Tropical Medicine Leptoconops b i t i n g on the b e a c h e s o f the I n d i a n O c e a n Specimens of Leptoconops (Styloconops) spinosifrons (Carter) and photographs of the habitat at Bentota in Ceylon were shown. This biting midge was very troublesome, biting on the beach in the late afternoon. The Ceylon Tourist Bureau wishes to develop Bentota as a tourist centre (see LINLEY and DAVmS, 1965).
MEETING
21
Mr. F. A. S. K u z o e , Mr. J. J. B. Gill a n d D r . W. W. M a c d o n a l d
Liverpool School of Tropical Medicine E v i d e n c e o f i n v e r s i o n s in the c h r o m o s o m e s Culex
in the testes o f Aedes aegypti a n d
pipiens fatigans
Squash preparations of the testes from pupae of Aedes aegypti and Culex pipiens I n both species there are 3 pairs of chromosomes and the preparations, stained with aceto-orcein, showed different stages of meiosis. I n one preparation of Ae. aegypti the three pairs of chromosomes showed 2, 3 and 4 chiasmata respectively at prophase I. Other preparations showed metaphase I, anaphase I and telophase I chromosomes and chromosome fragments. I n C. p. fatigans similar fragments were present in a preparation of anaphase I chromosomes. Chromosome fragments have been observed in 5 of 278 Ae. aegypti pupae and in 2 of 102 C. p. fatigans pupae. T h e fragments have been interpreted as the result of crossingover within inversions in the chromosomes.
fatigans were demonstrated.
Mr. A. K i r k w o o d
Central Veterinary Laboratory, Weybridge Some mites associated with poultry I n the course of a survey of mites on 2,497 chickens submitted for post-mortem examination the following mites were found: Dermanyssus gallinae, Liponyssus sylviarum,
Cnemidocoptes mutans, Syringophilus bipectinatus, Macrocheles matrius, Haemolaelaps casalis, and Acarus siro. These mites were demonstrated. Mr. J. L i u l e y
London School of Hygiene and Tropical Medicine R e a r i n g l a r v a e o f Leptoconops bequaerti Kieffer (Diptera: C e r a t o p o g o n i d a e ) i n t h e field
Leptoconops bequaerti is a small biting midge which occurs in Jamaica and other areas in the Caribbean. It is important because it presents a threat to the frequently enormous investments made in promoting tourism in the island. I n fact, L. bequaerti has a particular significance in this respect, since it may breed in white sand beaches, which are suitable for tourist development, and since the females bite throughout the day in quite strong winds when the majority of visitors wish to use the beaches. Attempts to gain an understanding of larval biology in L. bequaerti were complicated by the fact that larvae could not be reared with any success in the laboratory. 3 traps were therefore designed in which larvae could be reared in the field. T h e construction of these traps, and their methods of use, were illustrated by diagrams and photographs. The function of all three designs was to aUow larvae of known origin to develop on the natural breeding sites, but in an environment isolated from any "wild" larvae present on the chosen site. Information was gathered on a variety of topics connected with larval biology. Some of these were: (1) the duration of the larval stage under various conditions, (2) larval survival, (3) effect of larval environment on the size of resulting adults, (4) the sex ratio, (5) the sequence of adult emergence. D r . B. R. L a u r e n c e
London School of Hygiene and Tropical Medicine Leptoconops b i t i n g on the b e a c h e s o f the I n d i a n O c e a n Specimens of Leptoconops (Styloconops) spinosifrons (Carter) and photographs of the habitat at Bentota in Ceylon were shown. This biting midge was very troublesome, biting on the beach in the late afternoon. The Ceylon Tourist Bureau wishes to develop Bentota as a tourist centre (see LINLEY and DAVmS, 1965).