Cellular immune responses of the yellow peach moth, Conogethes punctiferalis (Lepidoptera: Crambidae), to the entomopathogenic fungus, Beauveria bassiana (Hypocreales: Cordycipitaceae).

The yellow peach moth (YPM), Conogethes punctiferalis, is a destructive insect pest of maize in eastern China and adapts to diverse environments, especially against pathogens. In insects, innate immunity comprising both humoral and cellular defense responses, is the primary defense against invading microbial pathogens. In this study, we identified five types of circulating hemocytes from the hemolymph of YPM larvae and analyzed their alterations and functions in immune responses to the infection of Beauveria bassiana, an entomopathogenic fungus infesting many lepidopteran species. The identified hemocytes included prohemocytes, plasmatocytes, granulocytes, spherulocytes and oenocytoids. Significant decreases of total and differential hemocyte counts were recorded over time in larvae, after they were injected with B. bassiana conidia. Additionally, hemocyte-mediated phagocytosis and nodulation were initiated in the hemolymph of larvae from the B. bassiana conidia challenge. The introduction of DEAE-Sepharose Fast Flow beads stained with Congo red also induced a strong encapsulation response in the larval hemolymph. Our observations unravel the occurrence of phagocytosis, nodulation and encapsulation in the hemocoel of YPM larvae to fight against the fungal infection, and offer the first insight into the YPM immune system.

[Effects of temperature on growth, survival, and reproduction of Conogethes punctiferalis feeding on corn kernels]. / 温度对取食玉米籽粒桃蛀螟生长发育、存活和生殖的影响.

In order to examine the effects of temperature on the growth, survival, and reproduction of Conogethes punctiferalis (Lepidoptera: Crambidae) feeding on corn kernels, the life table parameters of C. punctiferalis at 21, 24, 27, 30 ℃ were calculated based on the age-stage two-sex life table theory, and then population dynamics of C. punctiferalis was projected based on these parameters. The results showed that the life cycles of the pest could be finished at all the four temperature treatments. The developmental duration of each stage shortened with increasing temperature, and there were significant differences among treatments. The highest fecundity (116.7 eggs per female), preadult survival rate (84.7%), and proportion of female (0.46) were observed at 24 ℃. The intrinsic rates of increase at 24, 27, 30 ℃ were 0.1059, 0.1101, and 0.1045 d-1, respectively. The finite rates of increase were 1.1117, 1.1164, and 1.1102 d-1, respectively. There was no significant difference among the three treatments, but the r and λ values were significantly higher than those at 21 ℃. The net reproductive rates (R0) at 21, 24, 27, 30 ℃ were 17.3, 53.7, 36.9, and 19.8, respectively. R0 at 24 ℃ was the highest. It suggested that survival rates, fecundities and female proportions of C. punctiferalis population were high at 24-27 ℃, which was the suitable temperature range for its growth, survival, and reproduction.