Sogatella furcifera is a major rice pest with wing dimorphism. DNA methylation is an important epigenetic modification that plays a role in gene regulation and phenotype variation in most organisms. The objective of the current research was to survey the frequencies and variation of cytosine methylation at CCGG sequences in macropterous female adults (MFA) and brachypterous female adults (BFA) of S. furcifera, and to determine the occurrence of methylation changes associated with wing phenotypes by using methylation-sensitive amplification polymorphism (MSAP). No differences were found in the average proportions of methylated CCGG sites between MFA and BFA, but there were significant differences for methylation patterns between MFA and BFA. The fully methylated ratio was 5.81% in BFA, much higher than 2.40% in MFA; while the hemi-methylated ratio was 4.35% in BFA, much lower than 8.35% in MFA. These results provide circumstantial evidence that DNA methylation might be related to wing phenotype variation in S. furcifera. We also cloned and got 14 satisfactory sequences, which displayed variable cytosine methylation patterns between MFA and BFA. All these data will facilitate the researches on the epigenetic mechanisms of insect wing polymorphism.

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Baculoviruses and parasitoids are important biological control factors of insects in integrated pest management. Microplitis bicoloratus Chen (Hymenoptera: Braconidae: Microgastrina) is a solitary endoparasitoid of beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) larvae. M. bicoloratus parasitized first to third instars of S. exigua and most effectively parasitized second instars. The survival rate of parasitoids emerging from S. exigua multiple nucleopolyhedrovirus (SeMNPV)-infected hosts decreased with increasing SeMNPV doses at second to fourth instars. In addition, the mortality rate of the host was > 80% when coinfected with SeMNPV and M. bicoloratus, regardless of virus doses or the timing of virus treatment. Occlusion body production was significantly reduced in parasitized hosts. A comparison of host weights showed that hosts coinfected with SeMNPV and M bicoloratus were significantly lighter than those infected with SeMNPV alone, suggesting that the decrease in virus yield resulted from a reduction in larval growth. The viral genome copy number in parasitized host was significantly lower than that in nonparasitized host at 48 and 72 h postinfection. These results suggest that SeMNPV and M. bicoloratus are compatible as S. exigua control agents.

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