CHAPTER 2: Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) colony
2.3 Results
2.3.3 Optimization of the Chilo partellus artificial diet
In Experiment One; there was a significant difference between diets with respect to mean larval weight (Appendix 2.1). Diets One and Two differed significantly from Diets Three and Four in terms of mean larval weight (Table 2.6). Mean larval weight was significantly higher for Diets Three and Four, which had cane leaf powder of 45g and 55g per 1L, respectively. There was no significant difference between diets with respect to larval survival in Experiment One (Appendix 2.2). However, Diet Three gave the highest survival percentage (50.83%) (Table 2.6).
There was a significant difference between diets for mean larval weight in
Experiment Two (Appendix 2.3). Diet Two, which incorporated non-fat milk powder, resulted in a significantly higher larval weight than Diet One, which had a zero level of non-fat milk powder (Table 2.6). However, there was no significant difference between the diets in terms of larval survival (Appendix 2.4), although Diet Two gave a higher survival percentage (45%) than Diet One (30.17%) (Table 2.6).
In Experiment Three a, there was a significant difference between diets with respect to mean larval weight (Appendix 2.5). Diet Two had a significantly lower mean larval weight, whilst Diet Four had a significantly higher mean larval weight compared to the rest of the diets (Table 2.6). There was no significant difference in mean larval weight between Diets One and Three, although Diet Three gave a higher larval weight than Diet One (Table 2.6). There was also a significant difference between diets with respect to survival percentage for this experiment (Appendix 2.6). Diets Three and Four resulted in significantly higher survival percentages than did Diets One and Two, with Diet Three (65g cane leaf powder + 23.5g non-fat milk powder + 17.5g whole egg powder in 1L) resulting in the highest survival percentage of larvae (73.3%) (Table 2.6).
Again, there was a significant difference between diets with respect to mean larval weight for Experiment Three b (repeat of Experiment Three a) (Appendix 2.7), where Diet Three gave a significantly higher mean larval weight compared to the rest of the diets, and Diet Two gave a significantly lower mean larval weight than Diets Three and Four (Table 2.6). These results concurred with those of Experiment Three a.
There was also a significant difference between diets for larval survival (Appendix 2.8), where Diet Four resulted in a significantly lower larval survival percentage than
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Diet Three, which showed the highest larval survival percentage (45.83%) (Table 2.6).
In Experiment Four a, using the 500 ml plastic jars, there was a significant difference between diets for mean larval weight (Appendix 2.9). Diet three (65g cane leaf
powder + 23.5g non-fat milk powder + 17.5g whole egg powder in1L) gave a
significantly higher mean larval weight than the other diets (Table 2.7). Diets One and Two gave the lowest mean larval weights, although they did not differ significantly from larvae living on Diet Four. Again, in Experiment Four b there was a significant difference between diets for mean larval weight (Appendix 2.10). As with Experiment Four a, diet three (65g cane leaf powder + 23.5g non-fat milk powder + 17.5g whole egg powder in 1L) gave a significantly higher mean larval weight compared to the rest of the diets. Experiment Five, which was used to compare the use of sterilized versus non-sterilized eggs, there were no significant differences between the two methods, with mean larval weight being very similar for both methods (Table 2.7).
There was a significant difference between diets with respect to larval weight for Experiment Six when using multicell trays (Appendix 2.12). Diet Three (65g cane leaf powder of NCo376 + 23.5 g non-fat milk powder + 17.5g whole egg powder in 1L) gave a significantly higher mean larval weight compared to the other diets (Table 2.8). No significant difference between diets for larval survival was found for Experiment Six (Table 2.8).
Overall, vials gave higher larval survival percentages than the plastic jars and multicell trays, which gave very low larval survival percentages. The diets with increased proportions of cane leaf powder and with the incorporation of non-fat milk powder and egg powder gave higher mean larval weights than the standard diet in all inoculation techniques tested. The diet containing 65 g cane leaf powder + 17.5 g egg powder + 23.5 g milk powder in 1L total was the best diet overall because it consistently gave a high mean larval weight and larval survival percentages in Experiments Two, Three, Four, Five, Six and Eight. Larval survival percentage was also better for the diet containing 65 g cane leaf powder + 17.5 g egg powder + 23.5 g milk powder in 1L compared to the other diets when tested in all of the
experiments, and gave the highest overall larval survival percentage (73.3%) in Experiment Three a when using vials.
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Table 2.6 Effect of different artificial diets in vials on the survival and weight of Chilo partellus larvae. Larval weight data was subjected to REML variance component analysis and survival data was subjected to GLMM analysis, the Sidak test was used to separate means, and log10 or square root transformation was used where
necessary. Untransformed data is presented here.
Experiment Diet Mean larval weight (g) Survival No. (%)
1 1 0.03939 ± 0.0040a 40 ± 4.491a
2 0.04838 ± 0.0061a 36.67 ± 4.418a 3 0.09324 ± 0.0052b 50.83 ± 4.583a 4 0.07446 ± 0.0261b 38.33 ± 4.457a 5 0.04512 ± 0.0037a 41.67 ± 4.519a
2 1 0.00778 ± 0.0013a 39.17 ± 4.475a
2 0.0492 ± 0.0035a 45 ± 4.561a
3 1 0.05434 ± 0.0108b 25 ± 3.969a
2 0.00386 ± 0.0014a 12.5 ± 3.032a 3 0.06686 ± 0.0038b 73.3 ± 4.054b 4 0.1158 ± 0.0051c 62.5 ± 4.438b
4 1 0.03146 ± 0.0042ab 30 ± 4.201ab
2 0.01937 ± 0.0025a 34.17 ± 4.348ab 3 0.07046 ± 0.0109c 45.83 ± 4.568b 4 0.03732 ± 0.0038b 28.33 ± 4.131a
Mean ± SE, values in a column followed by the same letter are not significantly different using the Sidak test (P = 0.05)
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Table 2.7 Effect of different artificial diets and inoculation techniques using 500 ml plastic jars on the weight of Chilo partellus larvae. Larval weight and survival number were collected 27 days after inoculation. Larval weaight data was subjected to REML variance component analysis, Sidak test, and log10 transformation was used where necessary. Untransformed data is presented here.
Experiment Diet
Mean larval weight (g)
Survival No. (%)
5 1 0.0283 ± 0.005a 2.8
2 0.0141 ± 0.0044a 3.6 3 0.0756 ± 0.0069b 14 4 0.0429 ± 0.0045a 16.4
6 1 0.0184 ± 0.0030a 22
2 0.0126 ± 0.0079a 3.6 3 0.0852 ± 0.0103b 4.4 4 0.0141 ± 0.0055a 5.2
7 1 0.0241 ± 0.0026a 7.4
2 0.0227 ± 0.0018a 8.6
Mean ± SE, values in a column followed by the same letter are not significantly different using the Sidak test (P = 0.05)
Table 2.8 Effect of different artificial diets using multicell trays on the mean larval weight of Chilo partellus. Larval weight data was subjected to REML variance component analysis and survival data was subjected to GLMM analysis, the Sidak test was used to separate means, and log10 or square root transformation was used where necessary. Untransformed data is presented here.
Experiment Diet Survival No. (%) Mean larval weight (g) 8 1 5.556 ± 2.214a 0.079 ± 0.0102b
2 1.852 ± 1.303a 0.0319 ± 0.0173a 3 16.667 ± 3.603a 0.1231 ± 0.0127d
Mean ± SE, values in a column followed by the same letter are not significantly different using the Sidak test (P = 0.05)
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