Frozen section and electron microscopy studies of the infection of the red palm weevil, Rhynchophorus ferrugineus (coleoptera:curculionidae) by the entomopathogenic fungus Metarhizium anisopliae

SpringerPlus, Oct 2016

This study determined the pathogenicity of Metarhizium anisopliae strain SD-3 against invasive red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (coleoptera:curculionidae) larvae in Hainan Province, China. Inoculation of 1 × 108 conidia/mL caused 100 % mortality of R. ferrugineus, indicating that the conidia of strain SD-3 were highly virulent. The process of invasion mechanism was showed by scanning electron microscopy (SEM) and frozen section as follows. Once R. ferrugineus was infected by strain SD-3, M. anisopliae hyphae first invaded the cuticular and body cavity of R. ferrugineus. Secondly, well-developed muscles, fat, tracheaes and digestive tube tissues in the abdomen of R. ferrugineus were then decomposed and absorbed by M. anisopliae hyphae, leading to the total destruction of the larvae. Finally, M. anisopliae hyphae reproduced, resulting in a large number of conidia in the body of RPW. The SEM and frozen section are convenient tools to observe the mode of action of entomopathogenic fungi and to observe how M. anisopliae is able to colonize and infect the host.

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Frozen section and electron microscopy studies of the infection of the red palm weevil, Rhynchophorus ferrugineus (coleoptera:curculionidae) by the entomopathogenic fungus Metarhizium anisopliae

Sun et al. SpringerPlus Frozen section and electron microscopy studies of the infection of the red palm weevil, Rhynchophorus ferrugineus (coleoptera:curculionidae) by the entomopathogenic fungus Metarhizium anisopliae Xiaodong Sun 0 2 3 Wei Yan 0 3 Jing Zhang 0 3 Xiaoqing Niu 0 3 Fuheng Li 2 Weiquan Qin 0 3 Guangchang Ma 1 0 Hainan Key Laboratory of Tropical Oil Crops Biology/Coconuts Research Institute, Chinese Academy of Tropical Agricultural Sciences , Wenchang 571339, Hainan , People's Republic of China 1 Environment and Plant protection Research Institute, Chinese Academy of Tropical Agricultural Sciences , Haikou 571101, Hainan , People's Republic of China 2 College of Science, Northeast Agricultural University , Harbin 150030, Heilongjiang Province , People's Republic of China 3 Hainan Key Laboratory of Tropical Oil Crops Biology/Coconuts Research Insti- tute, Chinese Academy of Tropical Agricultural Sciences , Wenchang 571339, Hainan , People's Republic of China This study determined the pathogenicity of Metarhizium anisopliae strain SD-3 against invasive red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (coleoptera:curculionidae) larvae in Hainan Province, China. Inoculation of 1 × 108 conidia/mL caused 100 % mortality of R. ferrugineus, indicating that the conidia of strain SD-3 were highly virulent. The process of invasion mechanism was showed by scanning electron microscopy (SEM) and frozen section as follows. Once R. ferrugineus was infected by strain SD-3, M. anisopliae hyphae first invaded the cuticular and body cavity of R. ferrugineus. Secondly, well-developed muscles, fat, tracheaes and digestive tube tissues in the abdomen of R. ferrugineus were then decomposed and absorbed by M. anisopliae hyphae, leading to the total destruction of the larvae. Finally, M. anisopliae hyphae reproduced, resulting in a large number of conidia in the body of RPW. The SEM and frozen section are convenient tools to observe the mode of action of entomopathogenic fungi and to observe how M. anisopliae is able to colonize and infect the host. Metarhizium anisopliae; Rhynchophorus ferrugineus; Frozen section; Electron microscopy studies - Invasive red palm weevil (RPW), Rhynchophorus ferrugineus Olivier (coleoptera:curculionidae), is an important pests of a world range of palms of economic importance (Faleiro 2006). R. ferrugineus was originally reported in India, while now has been widely distributed in Asia, Africa, Australian (Fiaboe 2012; Kehat 1999; Mankin 2009). In China, R. ferrugineus is considered as a quarantine pest, and it has been found in 19 species of 15 palm genera (Dembilio et al. 2009). According to international standards for pest measurements (ISPM). This indicates R. ferrugineus can easily settle down in China, where it potentially poses a great threat to palm trees (Wu et  al. 2007). According to IPM strategy, several control methods have been used to R. ferrugineus invasion of palms, These methods include, cutting down and burning infected palms, trapping adult R. ferrugineus, chemical control, host plant resistance, bacteria control, viruses control, nematodes mites control, parasitoid and predator insects, male sterile techniques and so on (Faleiro 2006; Francardi et  al. 2013). Beside these, a number of entomopathogenic fungi (Metarhizium anisopliae, Beauveri bassiana, Aspergillus sp., Trichothecium sp., Penicillium sp., Fusarium sp.) isolated from naturally infected R. ferrugineus © 2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. as a biological control agent against this weevil (Ghazavi and Avand-Faghih 2002; Gindin et  al. 2006; Dembilio et  al. 2010; Güerri-Agulló et  al. 2011; Francardi et  al. 2013), Metarhizium anisopliae is one of the most commonly studied species of entomopathogenic fungi, it is environmentally-friendly and harmless to human. However, M. anisopliae was discovered in naturally infected R. ferrugineus in Egypt and this strain caused a high mortality rate for larval and adult stages only under laboratory conditions (Merghem 2011; Cito et al. 2014). Despite investigations of infection patterns and histopathology of M. anisopliae in selected insects is of economic importance, less study has documented the histopathology of M. anisopliae in R. ferrugineus (Toledo et al. 2010). Moreover, as the R. ferrugineus is highly promiscuous and adults live in aggregation, the fungi could spread in the population, infecting healthy insects by horizontal transmission, as suggested also by Llácer et al. (2013) and Francardi et al. (2013). Scanning electron microscopy (SEM) has frequently been used to evaluat (...truncated)


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Xiaodong Sun, Wei Yan, Jing Zhang, Xiaoqing Niu, Fuheng Li, Weiquan Qin, Guangchang Ma. Frozen section and electron microscopy studies of the infection of the red palm weevil, Rhynchophorus ferrugineus (coleoptera:curculionidae) by the entomopathogenic fungus Metarhizium anisopliae, SpringerPlus, 2016, pp. 1748, Volume 5, Issue 1, DOI: 10.1186/s40064-016-3416-6