Table 1.
Cumulative mortality (%) of Aedes aegypti larvae due to the exposure to different concentrations (nematodes per ml) of infective third stage larvae of Steinernema carpocapsae and the values of the physicochemical parameters from the plastic containers mimicking crypt vases.
| Time (h) | Cumulative mortality (%) | Oxygen (mg/L) | Temperature (°C) |
|---|---|---|---|
| Control without nematodes | |||
| 10 | 0 | 5.12 | 26.30 |
| 22 | 4 | 1.73 | 29.00 |
| 34 | 8 | 1.24 | 26.60 |
| 46 | 10 | 1.10 | 28.00 |
| 58 | 12 | 0.97 | 25.60 |
| 70 | 12 | 0.60 | 27.70 |
| 1250 nematodes/ml | |||
| 10 | 0 | 1.78 | 26.20 |
| 22 | 6 | 1.41 | 29.10 |
| 34 | 20 | 1.05 | 27.00 |
| 46 | 36 | 1.03 | 28.00 |
| 58 | 48 | 1.02 | 25.00 |
| 70 | 54 | 1.02 | 27.70 |
| 2500 nematodes/ml | |||
| 10 | 0 | 1.69 | 26.20 |
| 22 | 2 | 1.56 | 29.40 |
| 34 | 12 | 1.28 | 26.60 |
| 46 | 18 | 1.10 | 28.20 |
| 58 | 26 | 1.02 | 25.00 |
| 70 | 36 | 0.68 | 27.60 |
| 3125 nematodes/ml | |||
| 10 | 0 | 1.61 | 26.00 |
| 22 | 2 | 1.28 | 29.60 |
| 34 | 10 | 1.05 | 26.90 |
| 46 | 16 | 0.88 | 28.20 |
| 58 | 20 | 0.50 | 25.30 |
| 70 | 26 | 0.29 | 27.50 |
| 3750 nematodes/ml | |||
| 10 | 0 | 1.54 | 26.00 |
| 22 | 2 | 1.10 | 29.40 |
| 34 | 10 | 0.71 | 26.80 |
| 46 | 14 | 0.52 | 28.00 |
| 58 | 16 | 0.48 | 25.00 |
| 70 | 22 | 0.33 | 27.70 |
Fig. 1.
PCR results of the experimental infection of Aedes aegypti larvae with the nematode Steinernema carpocapsae. PCR products were separated using 1% agarose gel electrophoresis. MW = molecular weight marker, 1,000 bp; C+ =positive control; C− = negative control; S1 to S6 included the DNA of individual A. aegypti larvae infected with S. carpocapsae.
Fig. 2.
Histological sections of Aedes aegypti mosquito larvae experimentally infected with the entomopathogenic nematode Steinernema carpocapsae. A) mosquito larva with light infection. Note the presence of the infective third stage of S. carpocapsae in the midgut (mg) of the larva. B) Heavily infected mosquito larvae with third stage larvae of S. carpocapsae in the midgut (mg). Note that the peritrophic membrane is necrosed and heavily infected by bacteria presumably Xenorhabdus nematophila. Lettering: act, annular chitinous thickening; px, pharynx; oe, oesophagus; pv, proventriculus; Sc, Steinernema carpocapsae; sg, salivary glands; gc, gastric caeca; pm, peritrophic membrane; mg, mid-gut. Scale bar: 100 μm.
Fig. 3.
Cumulative mortality (in percentage) of the larvae of Aedes aegypti exposed to different concentrations of the entomopathogenic nematode Steinernema carpocapsae. The black columns represent the mean values of the cumulative of mortality (%), and the error bars are the standard deviation (SD) values. Letters on the columns represent the posthoc difference in mean values of the percentage of mortality, which were determined using the LSD Fisher method at p<0.05. Columns with a common letter were not significantly different (p <0.05).