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.

No abstract

Mangrove endophytic fungus 1893 was isolated from Kandelia candel from an estuarine mangrove on the South China Sea Coast. Two new lactones 1893A and 1893B, together with other known compounds, have been isolated from its fermentation broth. To classify the endophyte correctly for further industrial application, a combination of morphological and molecular techniques was used to approach its identity. The endophyte was compared with similar species having trichogynes or trichogyne-like hyphae which apparently fused with antheridium-like hyphae, and perithecia initials developing from an ascogonial coil surrounded by enveloping hyphae in early developmental stages on pure culture. Further morphological characteristics on host and non-host were used for comparison with similar species when the endophyte was cultivated on leaves of Kandelia candel and Mangifera indica, respectively, which resulted in classifying the endophyte as a Phomopsis species. The ITS sequence of rDNA was used to infer its phylogenetic relationships with Phomopsis species that resembled the strain in morphology or ecology. Finally, the endophyte was identified as Diaporthe phaseolorum var. sojae based on morphological and molecular evidence. Our study is a first report of Diaporthe phaseolorum var. sojae isolated from mangrove Kandelia candel.

This study evaluates the effect of gamma radiation on the spore activity, toxicity, and crystal structures of two engineered Bacillus thuringiensis (Bt) strains, TnX and TnY, and the reference Bt strain HD-1. We attempted to identify dosages of cobalt-60 gamma radiation that would inactivate Bt spores but not affect its toxicity. In the radiation dosage range of 10-15 kilogray, no viable spore formation and no significant reduction of the efficiency of Bt against lepidopteran larvae were observed. However, further sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results show that the components of the protoxin are affected by gamma radiation and that some bands are absent after treatment compared with the controls; the change in the protoxin band pattern depends on the type of Bt strain. Furthermore, the spore crystal structure of three Bt strains was studied with scanning electron microscopy and transmission electron microscopy. The results show that there are no changes in the size or shape of the treated Bt spores and crystals compared with the controls. The use of gamma radiation is effective to inactivate the spores of engineered Bt strains while preserving stable Bt toxicity against the target insect larvae.

A mangrove endophytic fungus 1403 isolated from the South China Sea Coast, which is able to produce griseofulvin and anthracenediones under submerged fermentation, was compared with Fusarium genus with the similar morphological characters such as elongated, microconidium-producing conidiophores, ovoid microconidia and straight to slightly curved macroconidia. It was found that the fungus 1403 resembles pathogenic F. verticillioides (teleomophy Gibberella moniliforme) in the production of false head or chains and abundant microconidia on the aerial mycelium, but different in the occasional formation of polyphialides with relatively long as well as short monophialides, in its typical coiled hyphae and mycelia fusion. Through maximum Parsimony and Bayesian analyses, the fungus 1403 was further compared with some similar Fusarium species. The results indicated that this endophyte was identified as Fusarium proliferatum based on the analyses of partial 18S and 28S rDNA genes, ITS region, and EF-1α gene.