Wolbachia also seems to potentiate the physiological and behavioral effects of SZPE in maize weevils, both directly and indirectly, based on the direct and indirect effects evidenced in our path diagram. Furthermore, the complete suppression of Wolbachia and SZPE prevented maize weevil reproduction, although unfertilized eggs were laid by the thermally treated female weevils, suggesting a potentiation effect of the latter, with the former favoring reproductive output. Nonetheless, the thermal stress imposed on the insect may also have contributed to preventing their reproduction, considering that the progeny production was assessed in the thermally treated insects, unlike in the antibiotic-treated weevils, where the progeny was the target of the assessments. SZPE load was of primary importance for the maize weevil, favoring higher respiration rate and grain consumption, which corresponded to improved gain in body mass in weevils with higher loads of this symbiont. The high body mass also exhibited a significant effect on insect behavior, particularly flight activity, aided by respiration rate. Earlier studies on the physiological role of SPE presence indicated involvement in nutrient provision and energy metabolism. Our results support this role and further indicate that such physiological effects are translated into gain in body mass and higher activity, particularly flight activity. Although our path analysis did not provide evidence for increased overall progeny production in weevils with endosymbiont loads, the Wolbachia load positively affected fertility. Furthermore, daily progeny production was delayed with the reduction in endosymbiont load, particularly the drastic suppression of the SZPE load obtained with ciprofloxacin. This delayed progeny production had a negative effect on the weevil population growth, indicating an important reproductive role of SZPE in the maize weevil. Further evidence of Wolbachia and SZPE suppression leading to reproductive impairment is also provided by the inability of thermally treated maize weevils to reproduce. Our results with varying endosymbiont loads and co-occurrence of SZPE and Wolbachia in the maize weevil reinforce the notion of the relative independence of the symbionts, which are able to coexist, although the primary effects of the SZPE load in the host seem amplified by the Wolbachia load. The c-Proteobacteria SPE, of which SZPE is a representative, is located in specific and differentiated cells in bacteria-bearing tissue found only in female germ cells and larval and ovarian bacteriomes. This characteristic distribution of SPE in weevils likely maintains these endosymbionts in relative isolation, minimizing potential interactions with MDV3100 CYP17 inhibitor co-occurring symbionts such as Wolbachia. In contrast, Wolbachia, which is a a-Proteobacteria with facultative association in grain weevils, is disseminated throughout the body cells.