Prey consumption and predation rate
The Odonata H. ephippiger nymph uses its grasping mouth
to catch the prey (snail) in one swift motion and then consume it.
Table 3 shows the effect of prey densities on the number of prey
consumed considering the prey sizes. Statistically, no significant
differences (P > 0.05) were obtained between the number of
preys consumed at lower density (5, 10 or 15 preys) whereas
significant differences (P < 0.05) were obtained for the higher
densities (20 or 25 preys) in comparison to the snail size
consumed. Small L. natalensis snails consumed by
H. ephippiger nymphs were significantly different (P < 0.05)
from large snails at high density (20 and 25 preys). Obtained
data shows that the nymph could consume a mean of
(20.00 ± 0.71), (15.20 ± 0.90) and (15.80 ± 1.10) preys/day
considering small-, medium- and large-size snail, respectively, at
density of 25 preys. The predation rate of H. ephippiger nymphs
on L. natalensis snails at different densities are shown in Table 4
and Figure 2. Regression analysis based on the mean predation
rate (n = 5 sets/prey density) showed significant differences in
the predation rate of H. ephippiger towards small, medium and large snails (r = −0.995, −0.991 and −0.931 with P
value = 0.004 0, 0.009 0 and 0.021 7), respectively. Obtained
data showed, increasing the snail density decrease the predation
rate, at density of 5 snail individuals, the predation rates were
(88.0 ± 4.8), (88.0 ± 4.8) and (80.0 ± 6.4)% while these were
differ at density of 25 snail individuals to (80.0 ± 2.8),
(61.0 ± 3.6) and (63.0 ± 4.4)% considering small-, medium- and
large-size snail, respectively.
Prey consumption and predation rateThe Odonata H. ephippiger nymph uses its grasping mouthto catch the prey (snail) in one swift motion and then consume it.Table 3 shows the effect of prey densities on the number of preyconsumed considering the prey sizes. Statistically, no significantdifferences (P > 0.05) were obtained between the number ofpreys consumed at lower density (5, 10 or 15 preys) whereassignificant differences (P < 0.05) were obtained for the higherdensities (20 or 25 preys) in comparison to the snail sizeconsumed. Small L. natalensis snails consumed byH. ephippiger nymphs were significantly different (P < 0.05)from large snails at high density (20 and 25 preys). Obtaineddata shows that the nymph could consume a mean of(20.00 ± 0.71), (15.20 ± 0.90) and (15.80 ± 1.10) preys/dayconsidering small-, medium- and large-size snail, respectively, atdensity of 25 preys. The predation rate of H. ephippiger nymphson L. natalensis snails at different densities are shown in Table 4and Figure 2. Regression analysis based on the mean predationrate (n = 5 sets/prey density) showed significant differences inthe predation rate of H. ephippiger towards small, medium and large snails (r = −0.995, −0.991 and −0.931 with Pvalue = 0.004 0, 0.009 0 and 0.021 7), respectively. Obtaineddata showed, increasing the snail density decrease the predationrate, at density of 5 snail individuals, the predation rates were(88.0 ± 4.8), (88.0 ± 4.8) และ (80.0 ± 6.4) %ขณะนี้แตกต่างกันที่ความหนาแน่นของ 25 บุคคลหอยทาก (80.0 ± 2.8),(61.0 ± 3.6) และ (63.0 ± 4.4) %พิจารณาเล็ก- กลาง - และหอยทากขนาดใหญ่ ตามลำดับ
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