## 2 Results  
The survival of newly hatched larvae of _A. grandis_ was affected by the ingestion of an artificial diet containing the different Bt proteins (Figure 1). The decreased survival of Bt-treated individuals increased with the increase in Bt protein concentration. For example, the analysis of the number of dead larvae after treatment at the highest dose (100 \(\upmu\)g\(\cdot\)g\({}^{-1}\)) was significantly different from that in the untreated group (one-way ANOVA, n = 269, F = 78, \(p<0.0001\)). At this dose, the Cry1 Ac, Cry1 Ba, and Cry7 Ab proteins had similar effects ([PERSON]'s post-test, \(p>0.99\) for any combination), but the results were statistically different from those regarding the effect of Mpp23 Aa/Xpp37 Aa ([PERSON]'s post-test, \(p>0.0001\)). Cry proteins showed corrected mortality below 50%, which shows the low susceptibility of these insects to these proteins. In contrast, when the toxicity of the Mpp23 Aa/Xpp37 Aa proteins was tested at the same concentrations, 100% mortality was observed.  
Moreover, the death of all larvae tested was found in all assayed concentrations, even at the lower level (1.56 \(\upmu\)g\(\cdot\)g\({}^{-1}\)). Based on these results, Mpp23 Aa/Xpp37 Aa proteins were selected for additional bioassay testing with lower toxin concentrations (ranging from 0.13 to 4 \(\upmu\)g\(\cdot\)g\({}^{-1}\)) to obtain dose-response data suitable for analysis. An example of the effect of these proteins can be observed in Figure 2.  
The probit analysis was applied to the data obtained, estimating the bioassay parameters (Table 1). In addition, the analysis provided some extrapolated data of lethal concentration (LC) parameters useful for toxicity comparisons. As expected, Cry1 Ac protein (described as a Coleopteran non-toxic) was marginally toxic (indicated by a high LC\({}_{50}\) value). Based on the LC\({}_{50}\) values obtained, Cry1 Ba and Cry7 Aa were slightly more toxic than Cry1 Ac; however, the test of the hypothesis that slopes and intercepts are the same, discarded significant differences (\(\chi^{2}\) = 7.04, degrees of freedom, d.f. = 4).  
Figure 1: Corrected mortality [15] of _A. grandis_ larvae after seven days of protein intake in an artificial diet at seven concentrations of different _B. thuringiensis_ Cry proteins. Error bars represent the mean standard error. The error bars for Mpp23 Aa/Xpp37 Aa are not shown because of the death of all treated larvae in all replicates.  
Figure 2: Effect of Mpp23 Aa/Xpp37 Aa on _A. grandis_ larvae with 0.5 \(\upmu\)g\(\cdot\)g\({}^{-1}\) treatment. (**A**) Neonate larva at the start of the treatment (1 mm size), (**B**) larva on control untreated media after 7 days of treatment (5 mm size), (**C**) larva on Mpp/Xpp treated media after 7 days of treatment (1 mm size).  
On the other hand, the Mpp23 Aa/Xpp37 Aa proteins showed significantly different toxicity dynamics (slope parameter) to _A. grandis_ than to the Cry proteins tested, according to the previous test applied (\(\chi^{2}\) = 532, d.f. = 2). The Mpp23 Aa/Xpp37 Aa toxicity was higher than that of the Cry proteins tested, since they provided a higher response to the concentration (a slope value higher), and the LC\({}_{10}\) and LC\({}_{50}\) values were lower. Only the LC parameters ratio (LC Cry1 Ac protein/LC Mpp/Xpp proteins) could be provided, since the slopes were not parallel between Mpp/Xpp and the Cry proteins. The ratio of LC\({}_{10}\) and LC\({}_{50}\) values were 25 and 1761, respectively.  
The concentration of Mpp/Xpp proteins required to kill 90% of the treated larvae (LC\({}_{90}\)), which is significant for pest control, was estimated as 0.4 \(\mu\)g\(\cdot\)g\({}^{-1}\) (fiducial limits, FL\({}_{95}\) = 0.32-0.56), increasing the evidence of its high toxicity.