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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Mycology and Nematology Genetic Diversity and Biology Laboratory » Research » Publications at this Location » Publication #295951
Title: Biology of two species of Microcera associated with armoured scales on citrus in Australia

Author
item HANG, DAO - Plant Protection Research Institute - Vietnam
item BEATTIE, ANDREW - Western Sydney University
item Rossman, Amy
item BURGESS, LESTER - Western Sydney University
item HOLFORD, PAUL - Western Sydney University

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2015
Publication Date: 3/22/2015
Citation: Hang, D.T., Beattie, A.C., Rossman, A.Y., Burgess, L.W., Holford, P. 2015. Biology of two species of Microcera associated with armoured scales on citrus in Australia. Journal of Invertebrate Pathology. 14(4):1-14.

Interpretive Summary: Scale insects cause serious damage to trees crops such as citrus yet these pests can be controlled by helpful fungi without the use of harmful chemicals. In Australia when they stopped using copper and zinc sprays in the citrus orchards, the number of fungi on scale insects increased dramatically. This paper reports the presence in Australia of two species of fungi that occur only on scale insects that damage citrus trees. Reported in Australia for the first time, these fungi are accurately identified. In addition tests showed that the beneficial fungi can kill significant numbers of red scale and other scale insects on citrus. Factors that influence the abundance of the scale-killing fungi were investigated. This research will be used by plant pathologists who are working to use good fungi to control insect pests rather than spraying harmful chemicals.

Technical Abstract: Microcera coccophila has been regarded as an entomopathogen of armoured scales in Australia since the late 1800s. We confirmed its identity using morphological and molecular data. In addition, we report the related species M. larvarum for the first time in Australia. The sexual and asexual states of both species are described. Genetic variation in these species suggested the occurrence of phylogenetic species in citrus orchards in the midcoastal region of New South Wales in eastern Australia. We fulfilled Koch’s postulates for both fungi in separate bioassays with Aspidiotus nerii. Infection was not dependent on the reproductive status of the scale. We recorded M. coccophila as a parasite of Aonidiella aurantii (red scale), A. citrina, Lepidosaphes beckii, L. gloverii and Unaspis citri in citrus orchards in mid coastal New South Wales. We recorded M. larvarum in association with red scale and one or more species thatcould not be positively identified, due to their condition. A laboratory study showed that Iridomyrmex rufoniger, a common ant in Australian citrus orchards, can passively disperse conidia of M. coccophila. Field observations suggested that prevalence of the two fungal parasites in orchards is influenced by host scale densities, climate, and foraging by I. rufoniger workers on honeydew produced by their sternorrhynchan trophobionts, particularly Saissetia oleae. These foraging activities induced dense populations of red scale by disrupting the activities of the scale’s natural arthropod enemies followed by epizootics of M. coccophila that decimated populations of the scale.