Bioassay of Rongbao (Active Ingredients of Calcium Cyanamide) Against Housefly Maggots 105
where C is the mortality rate of maggots in con-
trol beakers and T is the mortality rate of maggots
in the treated beakers.
Microsoft Excel (version 2003) software was
applied to record primary data and calculate mor-
tality rate and adjusted mortality rate according
to formulas 1 and 2 listed above. Data for mean,
standard deviation (SD) and analysis of variance
(ANOVA) were calculated and analyzed using
SPSS 20 software.
Results and Discussion
Effect of CC on Maggots
To determine the effect of CC on maggots, mor-
talities following two concentrations of CC ex-
posure were compared to an equivalent control
group. Cumulative mortality rates of groups ex-
posed to two different concentrations of CC on
day 1, day 2 and day 3 were corrected for mor-
talities of corresponding control groups, where-
as for the other treatments no corrections were
made since their control mortalities measured
on corresponding day did not exceed the 5 %
level. CC-induced cumulative mortality mea-
sured on day 1, day 2 and day 3 was higher in
groups exposed to 2 % concentration compared
with groups exposed to 1 % concentration on the
corresponding day. The cumulative mortality rate
increased from 34.51 to 37.67 % on day 1, 89.80
to 100 % on day 2 and 100 to 100 % on day 3
as CC concentrations increased from 2 to 4 %,
respectively. Groups exposed to 2 % CC on day
1 demonstrated insignificantly higher mortal-
ity rates than 1 % counterpart (chi square = 0.51,
p = 0.48). However, once the period of maggots
treatment had proliferated for two days, exposure
to 2 % CC induced significantly higher mortality
rates (chi square = 23.21, p = 0) compared to 1 %
concentration. One percent CC-induced mortal-
ity rates measured on day 3 reached the complete
100 % level the same as 2 % CC-induced mortal-
ity rates measured on day 2. As for blank control
groups, null-mortality rates in housefly maggots
were observed with correction of mortality rates
in the treated groups in vain (Table 1 ).
Relationship Between CC Concentration
and pH Value
The performance of CC and non-CC larval rear-
ing medium differed within pH value. The pH
values of larval rearing medium were 7.0 and
7.5 after treatment with 1 and 2 % CC, respec-
tively, whereas that of the control group was
6.63. The non-CC larval rearing medium had less
pH value than CC 1 %, and then the 1 % concen-
tration had less pH value compared to 2 % con-
centration (Table 2 ). The positive relationship
of the concentration of CC dissolved in water
with the pH value was supported by the formula
y = 43.33x + 6.61 ( R^2 = 0.95, p < 0.01) (Fig. 1 ).
Common species of filth fly in and around
the home breed between manure and human and
livestock food from a wide range of human and
domestic animal (Bonnefoy et al. 2008 ). They are
not only a group of pests affecting growth, feed
intake and feeding efficiency of livestock and
poultry, but also pose a major threat to human
health (Bonnefoy et al. 2008 ; Schofield and Torr
2002 ; Yadav et al. 2006 ). The filth fly is primar-
ily a nuisance to human, livestock and poultry,
and also transmits pathogens and acts as a vector
for more than 100 human and animal intestinal
diseases (Bonnefoy et al. 2008 ; Coffey and Maier
1950 ; Round 1961 ). As a consequence, it has
now become a major focus of medical and veteri-
nary research and its control is an ongoing battle.
Pyrethroids, carbamates, organophosphates and
organochlorines-based products are insecticides
applied as aerosols, baits, granules or sprays for
larval and adult fly control (Bonnefoy et al. 2008 ;
Coffey and Maier 1950 ; Powell 1993 ; Rozendaal
1997 ; WHO 2006 ). However, the repetitive and
inappropriate use of synthetic pyrethroids has
been reported with different levels of resistance
or cross resistance in Chinese field-captured pop-
ulation. Such is often the case with carbamates
and organophosphates (Ma et al. 2004 ).
CC is a calcium compound commonly used
as N-resource fertilizer, first synthesized in 1898
by Adolph Frank and Nikodem Caro (van Der
Ploeg et al. 2001 ). It is commercially known as
Rongbao in China, and used as vegetable prod-
uct improver and inducer, micro-organisms con-