Table 1.
In vitro analysis of the susceptibility of M. javanica and M. incognita to four solubilized Bt nematicidal proteins. The toxicity parameters were obtained using POLO-PC probit analysis program (LeOra Software, Berkeley, CA, USA) and correspond to the 50% lethal concentration (LC50) with its 95% fiducial limits (FL95) and the slope of the dose-mortality curve with the error represented by the standard deviation. The toxicity curves obtained for Cry5, App6, Cry21, and Xpp55 in each of the nematode species were not parallel and therefore, the calculation of relative potencies was not applicable. The only exception occurred with Cry5 and Cry21 toxicity curves obtained with M. javanica (relative potency = 0.92, FL95 = 0.84–1.02). The relative potencies shown in the table were calculated by dividing the LC50 value of the Cry5 by that of the other proteins
| Bt protein | M. javanica | |||
| LC50 (µg/ml) | FL95 (µg/ml) | Slope | Relative potency (LC50 ratio)* | |
| Cry5 | 529 | 467–594 | 3.9 ± 0.2 | 1 |
| App6 | 234 | 176–289 | 3.0 ± 0.1 | 2.3 |
| Cry21 | 574 | 431–711 | 4.0 ± 0.1 | 0.9 |
| Xpp55 | 483 | 421–551 | 5.0 ± 0.2 | 1.1 |
| M. incognita | ||||
| Cry5 | 250 | 149–356 | 1.9 ± 0.1 | 1 |
| App6 | 181 | 144–220 | 3.9 ± 0.1 | 1.4 |
| Cry21 | 377 | 262–543 | 1.2 ± 0.1 | 0.7 |
| Xpp55 | 246 | 134–348 | 3.1 ± 0.1 | 1.0 |
*LC50 ratios in relation to Cry5 LC50 value