Methoxyfenozide and pyriproxifen alter the cellular immune reactions of Eurygaster integriceps Puton (Hemiptera: Scutelleridae) against Beauveria bassiana

Effects of the two insect growth regulators (IGRs) methoxyfenozide, 20-hydroxyecdysone (20E) agonist,and pyriproxifen, Juvenile hormone (JH) agonist, were examined on the cellular immune responses of theSunn pest, Eurygaster integriceps versus the entomopathogenic fungus Beauveria bassiana. The simultaneoustreatment with the IGRs and the fungal spores altered haemocyte count (total and differentiate), nodulationresponse and phenoloxidase (PO) activity in a dose- and time-dependent manner. It was observed thatdifferent concentrations of methoxyfenozide increased total and differentiate haemocyte numbers as wellas B. bassiana-induced nodulation response. In contrast with the JH agonist, pyriproxifen significantlydecreased total and differentiate haemocyte numbers and inhibited nodule formation in E. integricepsadults. The 20E agonist displayed major effects when injected at the doses 2.79 and 5.59 lg/mg adult. Incontrast, injecting adults by pyriproxifen significantly impaired their ability to raise an efficacious responseagainst the fungal spores. The ability of the two IGR analogues to interfere with activity of the PO systemin haemolymph of E. integriceps adults was also investigated 6 h after injection by fungal spores.Methoxyfenozide had an excitatory effect on PO activity when the 5.59 lg/mg concentration was usedagainst adults. Conversely, pyriproxifen had an inhibitory effect on PO activity when used at 1.49 lg/mgadult concentration. These findings demonstrate that pyriproxifenmayinterfere with cell-mediated immunityof E. integriceps. So, pyriproxifen could be a good candidate for the integrated control of the Sunn pest.