**5. Conclusions**

In conclusion, the current study successfully constructed cDNA libraries from di fferent tissues of the male mid-gut, female mid-gut, ovaries, and testes of two-spotted field crickets. The Illumina HiSeq platform generated an average of 7.9 G, 11.77 G, 10.07 G, and 10.07 G bases of outputs, which assembled into 121,025, 158,658, 72,216, and 157,036 UniGenes from the male mid-gut, female mid-gut, testes, and ovaries, respectively. The transcriptome analysis of the generated libraries revealed for the first time the identification of 492 di fferent types of genes under the categories including Pattern Recognition Receptors (62 genes), Signal modulators (57 genes), Signal transduction (214), e ffectors (36 genes), and others (123 genes) to regulate the immune mechanism under natural conditions among two-spotted field crickets. In summary, *G. bimaculatus* transcriptome analysis provides preliminary evidence for their survival through their sophisticated and a specialized broad spectrum host immune defence mechanism against natural pathogens. It will open new avenues of research to develop molecular insecticides, and drug development by targeting genes regulating host immune defence mechanisms.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2309-608X/6/4/232/s1, Table S1: Immune-related Pattern Recognition Receptors from the transcriptome of two-spotted field crickets, Table S2: Immune-related Signal Modulators from the transcriptome of two-spotted field crickets, Table S3: Immune-related Signal Transductors from the transcriptome of two-spotted field crickets, Table S4: Immune-related Effectors from the transcriptome of two-spotted field crickets, Table S5: Other Immune-related sequences from the transcriptome of two-spotted field crickets.

**Author Contributions:** A.H., A.M.A. and S.N.A.-K. conceived the idea. A.H., M.W.A., A.M.A. and S.N.A.-K. designed the experiments. A.M.A. provided the resources. A.H. and A.M.A. performed the experiments. A.H., M.W.A., A.M.A. and S.N.A.-K. analyzed the data. A.H. wrote the original draft. A.H., M.W.A., A.M.A. and S.N.A.-K. revised and edited the manuscript. A.H., M.W.A., A.M.A. and S.N.A.-K. approved the manuscript for publication. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Ministry of Environment, Water and Agriculture, Kingdom of Saudi Arabia and Institute of Research and Consultancy, King Faisal University, Kingdom of Saudi Arabia. "The APC was funded by the funder".

**Acknowledgments:** The authors would like to express their deepest gratitude to His Excellency, Mohammad bin Abdulaziz Al-Oahli, President of King Faisal University and the Director General, Plant Resources, Ministry of Environment, Water and Agriculture, Suliman Ali Al-Khateeb for their guidance and support. We greatly appreciate the assistance provided by the colleagues from the Institute of Research and Consultancy, King Faisal University, Kingdom of Saudi Arabia.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
