## 3 Results
### Expression of MEKRE93 and JH Biosynthesis Genes in _dsScg-Met_ Injected Males  
The efficiency of the RNAi-mediated knockdown of _Scg-Met_ was investigated by comparing the transcript levels of _Scg-Met_ in the fat body of _dsScg-Met_ and _dsGFP_ treated locusts on the day of dissections, 34 days after the adult molt. Our data indeed show a significant reduction of _Scg-Met_ transcript levels, by an average of 44%, in the fat body of _dsScg-Met_ injected locusts (\(p\) = 0.048) (Figure 1A). Moreover, the mRNA levels of the downstream factor _Scg-_Krh1, generally considered as an important indicator of the Met-mediated JH signaling activity, were significantly reduced in both the fat body (p = 0.0021) and the CA (\(p\) = 0.0079) of _dsScg-Met_ injected adult males, when compared to the _dsGFP_ injected control animals (Figures 1B and 2A). On the other hand, we detected a significant increase of the mRNA levels of the transcription factor _Scg-_E93 (\(p\) = 0.0079) and of the JH biosynthetic enzyme _Scg-_JHAMT (\(p\) = 0.008) in the CA of _dsScg-Met_ injected males compared to control (_dsGFP_) locusts, while an upward (but non-significant) trend was observed for the _Scg-CYP15A1_ transcript levels (\(p\) = 0.06) (Figure 2A). Figure 1: Relative mRNA levels measured in fat body tissue of _dsGFP_ and _dsScg-Met_ injected adult male desert locusts 34 days after the adult mol. (**A**) Transcript levels of _Scg-Met_ were significantly reduced in the fat body demonstrating that the RNAi mediated knockdown was successful. Transcript levels of (**B**) _Scg-Krhl_ and (**C**) _Scg-_IRP were significantly reduced, while transcript levels of (**D**) _Scg-_NP3 and (**E**) _Scg-NP4_ were significantly increased in the fat body upon _dsScg-Met_ treatment. Transcript levels in the fat body were normalized against two reference genes, _Scg-Act_ and _Scg-Efla_. For every condition five biological replicates, each consisting of the pooled fat body samples from four individual locusts, were analyzed by q-RT-PCR. Data points are represented in a column graph as a floating bar (min to max value) with a line indicating the median. Significant differences (Student’s T-test) are indicated with asterisks (* \(p<0.05\); ** \(p<0.01\); *** \(p<0.001\)). The following statistical p-values were obtained: _Scg-Met_ (\(p=0.048\)), _Scg-Krhl_ (\(p=0.0021\)), _Scg-IRP_ (\(p=0.0008\)), _Scg-NP3_ (\(p=0.0059\)), _Scg-NP4_ (\(p=0.0007\)). (Abbreviations: ds = double stranded, _Scg = Schistocerca gregaria_, GFP = Green Fluorescent Protein, Met = Methoprene-tolerant, Kr-h1 = Krüppel-homolog 1, IRP = insulin-related peptide, NP = neuroparsin, Act = actin, Ef1a = elongation factor 1-alpha). Figure 2: **(A)** Relative mRNA levels of _Scg-Krh1_, _Scg-E93_, _Scg-JHAMT_ and _Scg-CYP15A_ measured in the _corpora allata_ (CA) of _dsGFP_ and _dsScg-Met_ injected adult male desert locusts 34 days after the adult mol. Data highlight the reduced _Scg-Krh1_ transcript levels, as well as the increased _Scg-E93_ and _Scg-JHAMT_ transcript levels, in the CA after _Scg-Met_ silencing. No significant change in the transcript levels of _Scg-CYP15A1_ was detected. Transcript levels in the CA were normalized against two reference genes, _Scg-Act_ and _Scg-Efla_. Data points are represented in a column graph as a floating bar (min to max value) with a line indicating the median. For every condition five biological replicates, each consisting of the pooled CA samples from four individual locusts, were analyzed by q-RT-PCR. Significant differences (Mann-Whitney U-test) are indicated with asterisks (**_p_ < 0.01; ***_p_ < 0.0001). The following statistical p-values were obtained: _Scg-Kr-h1_ (_p_ = 0.0079), _Scg-E93_ (_p_ = 0.0079), _Scg-JHAMT_ (_p_ = 0.008), _Scg-CYP15A1_ (_p_ = 0.06). (**B**) Normalized surface area of the CA in \(\mu\)m\({}^{2}\)/mg body weight of _dsGFP_ and _dsScg-Met_ treated animals. These data demonstrate that the CA significantly increased in size after _dsScg-Met_ treatment.