Beauveria brongniartii on white grubs attacking sugarcane in South Africa

Goble Tarryn, Costet Laurent, Robène Isabelle, Nibouche Samuel, Rutherford R.S., Conlong Desmond, Hill M.P.. 2012. Beauveria brongniartii on white grubs attacking sugarcane in South Africa. Journal of Invertebrate Pathology, 111 (3) : 225-236.

https://doi.org/10.1016/j.jip.2012.08.010

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Quartile : Q1, Sujet : ZOOLOGY

Résumé : Beauveria brongniartii (Saccardo) Petch fungal infections were observed on the melolonthid Hypopholis sommeri Burmeister (Coleoptera: Scarabaeidae) at two sites (Harden Heights and Canema) in the sugarcane producing area of the northern KwaZulu-Natal Midlands of South Africa. To initially identify the disease-causing fungus, 17 different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria spp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana s.s. (Balsamo) Vuillemin (17 isolates) and B. brongniartii (60 isolates) species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear Bloc gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. No genetic differentiation was observed between the Harden Heights and Canema populations; they thus may be considered one, structured and fragmented population over a distance of 5.5 km. Historically high levels of gene flow from swarming H. sommeri beetles is the proposed mechanism for this observed lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal forest to subterranean sugarcane habitats and vice versa in the environment by H. sommeri life stages. This is the first record of this species of fungus infecting H. sommeri larvae and adults in South Africa.

Mots-clés Agrovoc : Saccharum officinarum, Beauveria, phylogénie, variation génétique, microsatellite, lutte biologique, génétique des populations, Scarabaeidae

Mots-clés géographiques Agrovoc : Afrique du Sud

Mots-clés complémentaires : Beauveria brongniartii

Classification Agris : H20 - Maladies des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

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