"
ABSTRACTFlies have been the most common problem encountered in husbandry
management either in big animals or poultry; and it has not been easy to solve.
Disturbances caused by flies especially when the fly population is high do not
directly affect the animals themselves, but they rather socially have effects on the
breeders and the people living in the areas -around the farm. The use of
chemical insecticide in controlling fly population around animal farms has been
minimized, and nowadays natural enemies of flies-are more commonly used.
Research on the use of parasitoid insects in controlling flies has been
continuously conducted in some countries. ln Indonesia, there have not been
many studies done on the use of parasitoid insects particularly in animal farming
despite the country?s big potential in fauna.
The study on the use of parasitoid insects (Hymenoptera: Pteromalidae) in
controlling the population of filth flies in chicken farms was done by adopting data
from research done earlier for 3 years (1996 - 1998). This research was a
pioneering work and was the only research ever on the application of parasitoid
insects in the field of animal husbandry conducted at three chicken farms in Bogor Regency. Observation on fluctuation of filth fly population and that of
parasitoid in relation to some macro climate variables recorded at the nearest
weather station was done in the first year. In the following years, at one of that
chicken farm, an application of parasitoid by inundation of Spalangia endius
Walker (Hymenoptera: Pteromalidae) and monitoring of fluctuation of fly and
parasitoid population were done with regard to micro climate variables in the hen
houses measured by thermohygrograph.
Correlation between monthly average population of fly and parasitoid
during dry and rainy seasons and that of some macro and micro climate
variables was measured using correlation analysis for the identification of climate
variables that influenced the fluctuation of fly and parasitoid population the most.
Natural phenomena and all the results of the data processing above,
along with supply of secondary data derived- from existing references was
formulated into a system dynamic model. This is a model with a capability of
analyzing dynamic behaviors of fly and parasitoid population that forming a
complex system which characterized by its 'relation to several factors (biotic and
a biotic ones), related factors changing dynamically, as well as non linear relation
and feedback mechanism in it.
As far as macro climate is concerned, it has insignificant effects on the
fluctuation of fly and parasitoid population despite a significant difference in the
monthly total rainfall between the dry and the rainy seasons, because the
chicken manure as flies breeding place in the pen system of egg layer hens are
protected, and thus the climate variables does not directly affect them. The correlation of monthly average population of fly puparia and progeny parasitoid
indicated a high value (r = 0.914). lt showed the parasitoid characteristics being
pupal parasitoid and obligat toward fly puparia. The fluctuation of fly population
correlated only significantly with the humidity in the pen. Thus, the fluctuation of
fly population during the inundation period was not only infiuenced by parasitoid
activities but also by the fluctuation of monthly average humidity inside the hen
houses.
The construction of this dynamic- model was preceded by making a Causal
Loop Diagram (CLD), producing three main subsystems namely the subsystems
of fiy and parasitoid which each fonning a positive feedback cycle (R=
Reinforcing), and the subsystem of how the first two subsystems were related
which forming a negative feedback cycle (B= Balancing).
The Causal Loop Diagram described further how interaction mechanism
between the flies and the parasitoid was as well as how it related to other various
factors affecting that relation in a very complex system of chicken fami
ecosystem. Then, CLD was transformed into three models of Stock Flow
Diagrams (SF D), the first of which was SFD picturing the dynamic of fly
population and its parasitoid and its relation with factors of macro climate using
the data from the research result ofthe first working paper. This was a natural
model for interaction between flies and parasiloid in a conditional ecosystem
(Generic Model). The second model was the one for the use of parasitoid in
controlling population of flies with the application of parasitoid S. endius
inundation using the data from the research result of the second working paper (inundation Model). The last was a prediction model having some intervention to
identify the most important factors in the efforts of controlling the tlies by relying
on the role of parasitoid and a biotic factors. Due to limited data, the construction
of the model had to be carried out with strict assumptions.
With the advantages of system dynamic model which were possible for
being simulated and getting intervention, it was indicated that the increasing
capacity of parasitoid and pen humidity were important factors in the efforts of
controlling fly population in the ecosystem of chicken farm. Pen humidity was
basically a representation of manure condition being a breeding place for both
flies and parasitoid, and was closely related with the structure and management
of the pen, either chicken food quality. Meanwhile, increasing capacity of
parasitoid could mean increasing number as well as potential ofparasitoid in
attacking their host. in order to increase the parasltoid potential, efforts in habitat
conservation supporting the survival of parasitoid have to be a primary
consideration."
