|
Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 91, Num. 2, 1996, pp. 239-240
|
Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 91(1), Mar/Apr
1996
RESERCH NOTE: Reproductive Behavior of Ravinia belforti
(Prado & Fonseca,1932) (Diptera: Sarcophagidae) Females Reared,
in Isolation, in the Laboratory at Rio de Janeiro, RJ, Brazil
Jose Mario d'Almeida
Laboratorio de Biologia e Controle de Insetos Vetores,
Departamento de Biologia, Instituto Oswaldo Cruz, Av. Brasil
4365, 21045-900 Rio de Janeiro, RJ, Brasil
Code Number: OC96046
Size of Files:
Text: 7.6K
No associated graphics files
[TABLE AT END OF TEXT]
Key words: Ravinia belforti - reproductive behavior -
isolated females
Ravinia belforti (Prado & Fonseca, 1932) is a
sarcophagid fly of Neotropical distribution: Argentina, Brazil,
Colombia, Trinidad and Paraguay (HS Lopes 1969 A catalogue of
the Diptera of the Americas South of the United States,
Dept^o Zool Sec Agric S o Paulo 88 pp). In Brazil,
it is often captured in environments inhabited by man, thus
presenting a high degree of synantropy (AX Linhares 1981 Rev
Bras Entomol 25: 189-215, JM d Almeida 1984 Arq Univ
Fed Rur Rio de J 7: 101-110, ES Dias et al. 1984
Mem Inst Oswaldo Cruz 79: 83-91). Human and animal faeces
are the most sought substrate, both as baits or as a basis for
larviposition by this sarcophagid (Linhares loc. cit.,
d Almeida loc. cit., HS Lopes 1973 An Acad Brasil Ci
45: 279-291).
The synanthropic habits of R. belforti, and its
attraction for faeces, makes this sarcophagid a potential vector
of human and animal entero-pathogenic microorganisms. Despite its
public health importance there are no studies on its
reproduction, other studies are related, as pointed above, to
synanthropy and taxonomy (HS Lopes 1968 Rev Brasil Biol
28: 295-301, HS Lopes, ACR Leite1987 Mem Inst Oswaldo Cruz
82: 219-226).
The aim of the present paper was to evaluate the individual
reproductive behavior of R. belforti females. The
biological parameters, evaluated were: pre-larviposition and
larviposition periods, number of larvae per larviposition and
number of larvipositant females, female longevity and
reproductive potential (determined by the mean number of larvae
per larviposition and the mean number of ovarioles presented by
the females). For this last calculation, 45 females were
dissected (15 females from each essay).
Colonies of R. belforti were estabilished from adults
captured in the Zoological Garden and on the campus of Instituto
Oswaldo Cruz, both in Rio de Janeiro.
The collected flies were maintained in nylon screened wooden
cages (30 cm x 30 cm) and fed with a mixture of refined sugar,
powdered milk and yeast (2:2:1), besides a few slices of raw
liver and water ad libitum, changed daily. Fresh
human faeces were used as breeding substrate.
Three essays were performed, the first with 26 females from the
8th generation and the others with 25 from the 11th and 23 from
the 13th generations, under environmental conditions (22-28 C,
80 ñ 10% UR) at our Laboratory.
In order to start the assays, the newly emerged pairs (1F:1M)
were placed in individual cages (20cm x 20cm), and the rest used
to maintain the colony. Three days after emergence, the liver
slices were taken out, being replaced by human faeces as a
larviposition substrate. The faeces were kept in polyethylene
containers (4cm high x 5cm width), changed daily and left exposed
for 24 hr in the cages; after this period, the containers were
taken and larvae counted.
From the 74 R. belforti females studied, only 54
larviposited (77.3%). MV Ferraz 1992 (Mem Inst Oswaldo Cruz
87: 131-139) recorded 100% larviposition among females of
Peckia chrysostoma and Adiscochaeta ingens
(Diptera: Sarcophagidae) showing therefore a high degree of
fertility and suitability of these species to laboratory
conditions. These sarcophagids showed preference for decomposed
meat, unlike R. belforti which is essentially
coprophilic.
The pre-larviposition period of R. belforti ranged from
7 to 22 days, with an average of 12.8 days (Table I). Usually,
caliptrate Diptera develop a relatively short gonadotrophic
cycle, due to presence of politrophic ovaries: Phaenicia
cuprina (X= 4 days), Cochliomyia hominivorax (X= 6.3
days) and Chrysomya megacephala (X= 8.02 days) (AX
Linhares 1988 Rev Bras Entomol 32: 383-392).
Peak larvipositions occurred on the 14th and the 29th day after
emergence. In P. chrysostoma and A. ingens, these
peaks of larviposition were between the 34th and the 36th and at
the 24th day of life, respectively (Ferraz 1992 loc.
cit).
Reproductive potential of R. belforti females is shown
in Table II, as well as, the mean number of ovarioles per ovary.
The number of functioning ovarioles present in the flies ovaries
is widely variable, according to the species. The feeding and
environmental conditions (Ferraz 1992 loc.cit), varying
due to the number of gonadotrophic cycles (JR Anderson 1964
Ann Entomol Soc Am 57: 226-236). R. belforti
presented a low reproductive potential (43.56%) when compared
with the sarcophagids P. chrysostoma (63.3%) and A.
ingens (55.5%) already considered low by the author (Ferraz
1992 loc cit).
Preliminary observation on the behavior of R. belforti,
as related to the factors studied showed that this specie had a
low reproductive potential, when compared to others Neotropical
sarcophagids, that are not coprophilic. Thus, it is necessary to
compare these results to coprophilic sarcophagids, to evaluate
if this low reproductive potential is a characteristic of R.
belforti or if it is a peculiarity of coprophilic
sarcophagids.
Received 3 May 1995
Accepted 18 October 1995
TABLE I
Values of the various biological parameters of Ravinia
belforti maintained under laboratory contitions, in Rio de
Janeiro
Parameters Values
----------------------------
min max mean SD %SD
Pre-larviposition period (in days) 7 22 12.8 3.89 30.4
Larviposition period (in days) 1 55 17.14 13.8 80.7
Number of larvipositions 1 14 4.7 3.3 70.03
Mean number of larvae per larviposition
2.2 19 11.5 4.04 35.13
Mean number of larvae per females
5 163 56.1 46.26 82.47
Logevity of females 6 69 34.2 20.9
61.1
Min: Minimum; Max: Maximum; Sd: Standard Deviation; %Sd: %
Standard Deviation
TABLE II
Comparison among the number of ovirioles and reproductive
potential of Ravinia belfort, under laboratory conditions,
in Rio de Janeiro
Variables
a b c RP(%)
------------------------------------------------
13.2+/-2.6 26.4+/-5.1 11.5+/-4.04 43.56
A: Mean Ovirioles Per Avary; B: Mean Ovirioles Per Females; C:
Mean Number Of Larvae Per Larviposition; Rp(%): Reproductive
Potential
Copyright 1996 Fundacao Oswaldo Cruz
|