** RESULTS: CAPTIVITY STUDIES ON PREY-PREDATOR EXPERIMENT**

**8.1 Predators Behaviour**

**8.5.1 Predation Experiment of Dragonfly Nymphs and Poecilia reticulata**

** The predation experiment of dragonfly nymphs towards mosquito larvae species **
with variation in number of predator, water volume and number of predators were
presented in Figures 8.11 – 8.13. To investigate the efficiency of predatory of the selected
3 species of dragonfly nymph on 3 species of mosquito larvae, 3 types of variable were
introduced: (i) the predator number was either 1 or 2, (ii) the water volume was either 1 or
2 liters and (iii) the prey density was either 100 or 200 in number of individuals. Three
Odonata species were used in this experiment, they were *N. fluctuans, O. sabina *and *O. *

*chrysis as a predator and three mosquito larvae species as a prey: Ae. albopictus, Ae. *

*aegypti and Cx. quinquefasciatus larvae. *

Overall, the 3 species of dragonfly nymphs were consumed higher number of mosquito larvae in 2 conditions which is in (2 predators× 1 liter of water ×100 mosquito density) and in (1 predator × 1 liter of water × 200 mosquito density). However, dragonfly nymphs were consumed small number of mosquito larvae when exposed in 2 liters of water volume.

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**Figure 8.11 ** **Variations in daily feeding rate of three Odonata nymph species on the **
**fourth-instar Aedes albopictus larvae with variation in prey density, **
**water volume and number of predator **

**Figure 8.12 ** **Variations in daily feeding rate of three Odonate nymph species on the **
**fourth-instar Aedes aegypti larvae with variation in prey density, water **
**volume and number of predator **

152
**Figure 8.13 ** **Variations in daily feeding rate of three Odonate nymph species on **
**fourth-instar Cx. quinquefasciatus larvae with variation in prey density, **
**water volume and number of predator **

153
The predation experiment also observed in male and female guppy towards three
species of mosquito larvae (Figures 8.14 – 8.16). In all three experiments it showed that
female guppy consumed higher number of mosquito larvae than male guppy except in one
condition when male guppy consumed more larvae of *Cx. quinquefasciatus larvae in (2 *
predators × 1 liter of water × 200 mosquito density).

Female guppy consumed high number of mosquito larvae in (1 predator × 1 liter of
water × 200 mosquito density) of *Ae. albopictus, Ae. aegypti *and *Cx. quinquefasciatus *
larvae (Figures 8.14 – 8.16).

Male guppy consumed high number of mosquito larvae in different condition for
example they consumed more *Ae. albopictus and * *Cx. quinquefasciatus larvae in (2 *
predators × 1 liter of water × 100 mosquito density) but they consumed more Ae. aegypti
larvae (1 predator × 1 liter of water × 200 mosquito density). In all three experiments, both
male and female guppies consumed small number of mosquito larvae when exposed with
(1 predator × 2 liter of water × 100 mosquito density), where the water volume was
increased.

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**Figure 8.14 ** Variations in daily feeding rate of male and female guppies on

**fourth-instar Aedes albopictus larvae with variation in prey density, water **
**volume and number of predator **

**Figure 8.15 Variations in daily feeding rate of male and female guppies on **
**fourth-instar Aedes aegypti larvae with variation in prey density, water volume **
**and number of predator **

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**Figure 8.16 ** **Variations in daily feeding rate of male and female guppies on **

**fourth-instar Cx. quinquefasciatus larvae with variation in prey density, water **
**volume and number of predator **

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Table 8.7 shows the regression equations provided by multiple regression analyses
for predation on Ae. albopictus larvae by Odonata species. From the regression equation, it
was observed that factors such as number of predator, water volume and prey density
influenced the feeding consumption of Odonata species. For N. fluctuans prey density was
significantly affected the predation activities. The feeding rate of *N. fluctuans was higher *
when the prey density was low than when the prey density was high. The factor that
influences predation activities for *O. sabina was water volume. Its show negative *
relationship between feeding consumption and water volume; the feeding rate decreased
with increased water volume. The feeding rate of O. chrysis increased when the number of
predator increased.

Multiple regression analyses for predation of Ae. aegypti larvae by odonate species
have been depicted in Table 8.8. Only water volume and prey density were influenced the
predation activities. For *N. fluctuans and O. chrysis the prey density was influenced the *
predation activity. The feeding rate was higher when the prey density was low than when
the prey density was high. Water volume influenced the predation activities of *O. chrysis. *

The O. chrysis eat more larvae during water volume decreased.

Three factors such as number of predator (X1), water volume (X2) and prey density
(X3) were influenced the predation activities(Table 8.9). For *N. fluctuans, water volume *
was influenced the predation activities. Two factors influenced predation activities between
*O. sabina and Cx. quinquefasciatus *larvae. When the number of predator increased the
feeding rate also increased and they eat less when number of prey increased. However, for
*O. chrysis only one factor influenced the predation activity which is prey density. *

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**Table 8.7 ** **The regression equations of predation on ****Aedes albopictus larvae by ****different Odonate nymphs (Y) against the number of predator (X1), **
**water volume (X2) and prey density (X3) as variables **

**Predators ** **(Odonata **
**species) **

**Regression equations ** **R value **

*Neurothemis fluctuans * Y = 96.444 – 31.556 X3 0.88
*Orthetrum sabina * Y = 106.111 – 35.889 X2 0.75
*Orthetrum chrysis * Y =11.444 – 26.44 X1 0.78

**Table 8.8 ** The regression equations of predation on **Aedes aegypti larvae by ****different Odonate nymphs (Y) against the number of predator (X1), **
**water volume (X2) and prey density (X3) as variables **

**Predators (Odonata species) ** **Regression equations ** **R value **
*Neurothemis fluctuans * Y = 109.667 – 36.667 X3 0.87
*Orthetrum sabina * Y = 115.778 – 38.556 X2 0.78
*Orthetrum chrysis * Y = 84.222 – 22.778 X3 0.61

**Table 8.9 ** **The regression equations of predation on Cx. quinquefasciatus larvae by **
**different Odonate nymphs (Y) against the number of predator (X1), **
**water volume (X2) and prey density (X3) as variables **

**Predators ** **(Odonata **
**species) **

**Regression equations ** **R value **

*Neurothemis fluctuans * Y = 77.000 – 25.000 X2 0.84
*Orthetrum sabina * Y = 35.667+ 36.00 X1– 20.333 X3 0.89

*Orthetrum chrysis * Y = 114.000 – 35.667 X3 0.79

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Table 8.10 shows the regression equations provided by multiple regression analyses
for predation on *Ae. albopictus larvae by male and female guppies. From the regression *
equation, it was observed that factors such as number of predator, and water volume
influenced the feeding consumption of male guppy. Whereas for the female guppy only
water volume significantly affected the predation activities. It showed negative relationship
between feeding consumption and water volume; the feeding rate decreased with increased
water volume. The feeding consumption increased when the numbers of predator increased.

Multiple regression analyses for predation of *Ae. aegypti larvae by guppies have *
been depicted in Table 8.11. Only water volume and prey density influenced the predation
activities. The feeding rate was higher when the prey density increases and feeding rate
increases when water volume decreases.

Table 8.12 showed the factors that influenced the predation of both male and female
guppies towards *Cx. quinquefasciatus *larvae. When the number of predator increased the
feeding rate also increased and feeding rate decreased when search area was increased
(water volume increased).

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**Table 8.10 ** **The regression equations of predation on ****Aedes albopictus larvae by ****male and female guppy (Y) against the number of predator (X1), water **
**volume (X2) and prey density (X3) as variables **

**Predators ** **Regression equations ** **R value **

Male guppy Y = 16.67 + 48.67 X1 – 14.00 X2

0.99

Female guppy Y = 119.67 – 23.33 X2 0.66

**Table 8.11 ** ** The regression equations of predation on ****Ae. aegypti larvae by male ****and female guppy (Y) against the number of predator (X1), water **
**volume (X2) and prey density (X3) as variables **

**Predators ** **Regression equations ** **R value **

Male guppy Y = 125.33 – 32.67 X2 0.75

Female guppy Y = 92.00 – 15.00 X2 + 23.00 X3 0.96

**Table 8.12 ** **The regression equations of predation on Cx. quinquefasciatus larvae by **
**male and female guppy (Y) against the number of predator (X1), water **
**volume (X2) and prey density (X3) as variables **

**Predators ** **Regression equations ** **R value **

Male guppy Y = – 13.33 + 56.67 X1 0.92

Female guppy Y = 105.67– 20.33 X2 0.67

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