Memórias do Instituto Oswaldo Cruz Fundação Oswaldo Cruz, Fiocruz ISSN: 1678-8060 EISSN: 1678-8060 Vol. 91, Num. 3, 1996, pp. 299-300

RESEARCH NOTE

Pupation of Dermatobia hominis (L. Jr., 1781) (Diptera: Cuterebridae) Associated with Sarcodexia lambens (Wiedmann, 1830) (Diptera: Sarcophagidae)

Uriel Franco Rocha^+, Julio Mendes

Departamento de Patologia, Centro de Ciencias Biomedicas, Universidade Federal de Uberlandia, Caixa Postal 593, 38400-902 Uberlandia, MG, Brasil

Code Number: OC96059
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Key words: Dermatobia hominis - Sarcodexia lambens - larval development

[TABLE AT END OF TEXT] An extension course on farm animal parasites was conducted under the request of a group of livestock breeders and labourers who, among other subjects, asked to be instructed on the fundamental facts of the life cycle of the cattle grub Dermatobia hominis (Linnaeus Junior, 1781). For that purpose an experiment was mounted with adapted equipment available on farms, by means of which 3rd instar larvae collected from skin nodules of Bos indicus Linnaeus, 1758 were 'cultured' on sterilized soil.

Regional data - Rural zone of Cocalzinho, GO, located between 15.5^o - 16.0^o S and between 49.0^o - 49.5^o W, 1.185 m above sea level. Air temperature kept between the minimum 8^oC and the maximum 27^oC and air relative humidity around 69% during the observation period.

Sterilized soil - 600 g of soil was laid on a newspaper sheet in a baking aluminum pan (60 cm x 30 cm x 4 cm) and put in a domestic gas-oven set at its maximum temperature. After 90 min the paper borders not covered by soil were charred black and the protected part became dark brown, while the soil sample was reduced from 600 g to 523 g, so it was concluded to be sterilized. It was divided in three sub-samples seemingly equal, each of which was put into a clean cylindrical glass-pot. Each of these received 45 ml of filtered water.

Collection of grubs from cattle - Ten grubs were pressed out of their individual skin nodules into each of the three glass pots and upon the humid soil substract they contained. That was done while the zebuine hosts were restrained in a body compressing chute. Some exudate dropped on top of the soil with each larva thus collected. The pots were kept open during about 12 hr on a stable bench in order the cattlemen could observe the larvae burrowing into the soil; the pots were then closed on the top by a folded newspaper sheet tied in place with a piece of string.

Sarcodexia lambens (Wiedemann, 1830), adult flies - On the 20th and 21st days after the collection of D. hominis grubs, 13 adults flies identified as S. lambens were seen inside pots no. 1 and 3 (Table). No evidence of Sarcodexia invasion was found in pot 2. Two adult flies did not emerge from the 15 puparia recovered or were subject to some predatory organism (Table).

D. hominis adult flies - From the 32nd to the 35th day after their collection directly over humid soil substract, at least 50% of the larvae had developed into adult flies in the three pots (Table). After passing the soil through a sieve there were found in the first pot, besides S. lambens and D. hominis remains, a kind of silken cocoon containing chitinous debris and two larvae had disappeared. In the 3rd pot were detected the presence of the 'small common red home ant' (probably Myrmex sp.) and one corroded abdomen from female adult fly (Table).

It seems obvious that S. lambens larvae were laid in two of the pots while these were kept open in order the cattlemen could observe D. hominis larvae burrowing into the substract containing some of the host's skin exudate that may have attracted the sarcophagid fly. It is possible that only one S. lambens female flew unnoticed in and out of two of the three pots leaving there a few of its tiny 1st instar larvae. These may have fed later on the exudate and eventually on leftovers from D. hominis and even from S. lambens, specially from immature specimens dying and decaying without reaching the adult stage. The opportunism herein pointed out as one of S. lambens s behavioral features had not been described in Brazil, but its aptitude of developing within organic material from animal origin has been mentioned in this country (MJM Ferreira 1979 Rev Bras Biol 39: 773-781, J Mendes & AX Linhares 1993 Rev bras Ent 37: 355-364, JM d'Almeida 1984 Mem Inst Oswaldo Cruz 79: 413-417). This species is included among the synbovin Diptera by GP Oliveira (1986 Arq Biol Tecnol 29: 211-324), who did not find this species carrying D. hominis eggs and did not include it among species that breed in bovine feces (GP Oliveira et al. 1993 An 45 Reun SBPC).

The present study shows that the adopted crude methodology, besides being cheap and easy to employ, is adequate for the obtention of D. hominis adult flies under field conditions. It is recommended that the pots with soil substract be closed immediately after the larvae are directly collected into them, to avoid penetration of other arthropods, among them S. lambens.

^+Corresponding author. Fax: 55-34-218.2333
Received 5 July 1995
Accepted 29 January 1996

TABLE

Pupation of Dermatobia larvae associated with Sarcodexia lambens

                Dermatobia hominis           
Sarcodexia lambens        --------------------------------
-------  -----------------
Pot.  3rd   Emerged Empty   Dead Sterile Lost  Adult flies Empty 
no.   instar flies  pup-   larvae pupae larvae male female pup- 
      larvae       aria                                    aria
---------------------------------------------------------------
1      10      3      4      3      1     2     4     4     9  
2      10      7      7      2      1     -     -     -     -
3      10      5^a    5      4      1     -     2     3     6

Total  30     15     16      9      3     2     6     7    15

Copyright 1996 Fundacao Oswaldo Cruz