Decomposition and insect succession pattern on monkey carcasses placed indoor and outdoor with notes on the life table of Chrysomya rufifacies (Diptera: Calliphoridae)
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Date
2014-08
Authors
Ramayah, Sundharavalli
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Abstract
This study was conducted in the Durian Valley, USM, Penang from 15
February to 4 April, 11 June to 30 July and 10 October to 28 November, 2012, using
total of 18 monkey carcasses; 6 carcasses per study period. Five decomposition
stages were identified; fresh, bloated, active decay, advance decay in both outdoor
and indoor conditions and finally dry skeletal remain; in outdoor and mummified
remain; in indoor conditions for all study periods. Onset of decomposition stage
between the three study periods were significantly different (p<0.05) on outdoor
only; for advance decay and dry skeletal remain stages only. While, onset of
decomposition stage between the outdoor and indoor were signifantly different
(p<0.05), for active decay, advance decay and dry skeletal remain; in outdoor and
mummified remain; in indoor conditions in all study period. Diptera was the most
prominent Order of arthropod obtained in the present study. A total of 21 species of
dipterans were collected throughout the study period. Certain species of flies which
were obtained indoor, not obtained from outdoor. The exposed outdoor condition
made it easier for the flies to oviposit on the carcass, which occurred within 15-30
minutes of exposure. However there was a delay in the oviposition of fly, in the
indoor condition by two days. The colonization by the larvae of some of the species
was delayed in the indoor condition. The decomposition process of the carcass
placed indoor was prolonged compared to the outdoor. The major factor affecting the
variation in the decomposition process and insect succession patterns between all the
three study periods was solely rainfall. While, variation between indoor and outdoor
carcasses were influenced by ambient temperature, relative humidity, light intensity
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and insect abundance; accessibility of the insects to the carcasess, significantly
(p<0.05). Chrysomya rufifacies was the most abundant species collected in the field
during the early stage of decay and the life history of this fly was studied in the
laboratory conditions at temperature of 28 ± 2.5 ºC and 75 ± 10% R.H, to establish
its population dynamics. The collected raw data were analysed based on the agestage,
two-sex life table theory in order to consider both of the sexes and the variable
developmental rate among individuals and between sexes. The population
parameters; intrinsic rate of natural increase (r) was 0.2361 d-1, the finite rate of
increase (λ) was 1.2663 d-1, the net reproduction rate (R0) was 97.18 and the mean
generation time (T) was 19.36. The population parameters suggest that the C.
rufifacies population exhibited the r-strategy.
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Keywords
Chrysomya rufifacies