Entomopathogenic fungi of the oil palm pest, Zophiuma butawengi (Fulgoromorpha: Lophopidae), and potential for use as biological control agents Deane N Woruba, 1 * Michael J Priest, 2 Charles F Dewhurst, 3 Catherine W Gitau, 1 Murray J Fletcher, 2 Helen I Nicol 1 and Geoff M Gurr 1 1 EH Graham Centre, Charles Sturt University, Orange, NSW 2800, Australia. 2 EH Graham Centre, NSW Department of Primary Industry, Orange Agricultural Institute, Orange, NSW 2800, Australia. 3 PNG Oil Palm Research Association, Kimbe 621, WNB, Papua New Guinea. Abstract Oil palm, Elaeis guineensis Jacq., is an important cash crop in Papua New Guinea. Production is currently under threat from Finschhafen disorder caused by the planthopper Zophiuma butawengi (Heller), a native pest of coconut. The need for a non-chemical strategy to manage Z. butawengi is high because the industry is committed to sustainable production. One possible option is the development of biological control using entomopathogenic fungi, and this study aimed to assess the scope for such a technology. Field collections extending over three regions of West New Britain in the 2010 monsoon season yielded 38 mycosed cadavers. Only three yielded entomopathogenic fungi: two of Hirsutella citriformis Speare and one each of Metarhizium flavoviride var. minus Rombach, Humber and D.W. Roberts, and Purpureocillium lilacinum (Thom) Luangsa- ard, Houbraken, Hywel-Jones and Samson. The pathogenicity of each isolate to Z. butawengi was confirmed in a laboratory study. M. flavoviride var. minus killed Z. butawengi significantly more rapidly over the course of a 15-day period, and day 7 mortality was significantly greater than in water or nil control treatments. Given this pathogenic fungus was readily culturable and congenerics are used in other biological control treatments, it merits further investigation as a potential inundative entomopathogenic agent against Z. butawengi. Key words Planthopper, oil palm, Metarhizium flavoviride var. minus, Hirsutella citriformis, Purpureocillium lilacinum, pathogenicity. INTRODUCTION Oil palm, Elaeis guineensis Jacq. (Arecaceae), was introduced into Papua New Guinea (PNG) in the 1920s, but the industry did not develop until 1967 (Allen et al. 2009). In 2010, the value of palm oil represented 46% of all major agricultural export com- modities of PNG, making oil palm the most valuable agricul- tural commodity in PNG (Bank of Papua New Guinea 2011). The oil palm industry is now under threat by Finschhafen disorder (FD) caused by the planthopper, Zophiuma butawengi (Heller) (= Z. lobulata Ghauri) (Fulgoromorpha: Lophopidae) (Gitau et al. 2011a,b). FD was first recorded on coconut, Cocos nucifera L. (Arecaceae), and is also found on betel nut, Areca catechu L. (Arecaceae) (Ghauri 1967; Smith 1980a,b; Prior et al. 2001; Page 2004; Gitau et al. 2011b). These palm species play important roles in the livelihoods of the rural population (Allen et al. 2009). The coconut palm has a long history in PNG as an important source of food and as a cash crop (Allen et al. 2009). Betel nut is an important traditional plant and more recently has become an important cash crop within the local economy in PNG (Allen et al. 2009). The threat Z. butawengi poses to oil palm is probably the most significant. Although the loss of oil palm because of Z. butawengi has not been quanti- fied, losses on coconut were estimated to be a third of the crop, with a further 80% of coconut palms affected and 10% of affected palms died (Smith 1980b). Losses to oil palm of even a fraction of this magnitude would be economically devastating for PNG. FD was first described as a ‘plague infestation of coconut’ when a major outbreak affected palms in Finschhafen (Fig. 1), Morobe Province (MP), PNG (Ghauri 1967), hence the name ‘Finschhafen Disorder’. Fronds of the coconut become chlorotic and later necrotic from the tip back to the base of the frond. Despite regular sightings of Z. butawengi on coconut and betel nut along the north-eastern coastline on the island of New Guinea between Alotau, Milne Bay Province (MBP) and Finschhafen, MP (Smith 1980a), the spread of FD has been slow and sporadic. Apart from Finschhafen, further reports of FD on coconut have been made from Popondetta in the North- ern Province (NP), Losuia Island in MBP, and Banaule and Mai villages in West New Britain Province (WNBP) (Smith 1980a; Prior et al. 2001). During the infestation at Banaule and Mai villages, FD symptoms were also observed in neighbour- ing blocks of oil palm (Prior et al. 2001). Since then, there have been increasing reports of FD on oil palm in WNBP, *nabre3@gmail.com Austral Entomology (2013) ••, ••–•• © 2013 Australian Entomological Society doi:10.1111/aen.12073