Distribution and aspects of the biology and host range of Eurytoma sp. (Hymenoptera: Eurytomidae), a candidate agent for the biological control of Bryophyllum delagoense (Ecklon & Zeyher) Schinz (Crassulaceae) in Australia A.B.R. Witt 1,2* , A.J. McConnachie 1 & S. Docherty 1 1 Queensland Department of Natural Resources and Mines, South African Field Station, c/o ARC-PPRI, Private Bag X134, Queenswood, 0121 South Africa 2 Ecophysiological Studies Research Programme, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, WITS, 2050 South Africa Surveys were conducted in Madagascar for potential biological control agents for Bryophyllum delagoense (Ecklon & Zeyher) Schinz, an invasive plant in Australia. The phyto- phagous wasp Eurytoma sp. (Eurytomidae: Eurytominae) was found throughout the natural distribution of its host plant, B. delagoense, in southern Madagascar and was imported into South Africa for life history studies and preliminary host-range testing. The wasp proved to be a suitable candidate agent because it was easy to rear, had multiple generations per year and was damaging to its host plant in the field and under laboratory conditions. Eggs are deposited in the plantlets (bulbils), leaves and/or seedling stems and the larvae complete their development in the plant. There are five larval instars and pupation occurs in excavated pupal chambers within the plant. Adults emerge from plants 5–10 days after pupation and are short-lived. Preliminary host range trials revealed that Eurytoma sp. is oligophagous with larvae being able to complete their development on only three other species in the Crassulaceae. Extensive host range trials still have to be undertaken in Australia before the wasp can be considered for release as a potential biological control agent for B. delagoense. Key words: biology, Bryophyllum delagoense, Crassulaceae, distribution, Eurytomidae, Eurytoma sp., host range, Madagascar. INTRODUCTION The first recorded outbreak of Bryophyllum delagoense (Ecklon & Zeyher) Schinz (Crassulaceae, ‘mother-of-millions’) in Australia occurred in 1940 near Chinchilla, Queensland (Hannan-Jones & Playford 2002). The weed has subsequently become increasingly abundant in Queensland and is particularly prolific in the western Darling Downs districts and also on the northwest plains and coastal strip of New South Wales. Landholders are particularly concerned because of the plant’s toxicity to livestock (McKenzie & Armstrong 1986) and its ability to spread rapidly, either vegetatively through plantlets (bulbils) which drop off the ends of the leaves, or by seed. In 1999, Queensland’s Department of Natural Resources and Mines initiated a biological control programme against B. delagoense with the estab- lishment of a field station in South Africa. Several surveys were undertaken in the native range of B. delagoense in the south of Madagascar and these revealed a number of potential biological control agents, including the phytophagous wasp Eurytoma sp. (Hymenoptera: Eurytomidae: Eurytominae) (Witt & Rajaonarison 2004). The larvae are leaf- miners, causing the leaves to desiccate and drop off the plant. At high densities in the laboratory, a mature plant can lose all of its leaves. This paper reports on the distribution of Eurytoma sp. in southern Madagascar and aspects of its biology and host range that were studied in quarantine in South Africa. MATERIAL AND METHODS Field observations Seventy-five sites with B. delagoense were surveyed in southern Madagascar to record the presence of Eurytoma sp. larvae, adults and/or damage, during four separate trips in August 1999, February and December 2000, and June 2001 (Fig. 1). For addi- tional host records, the related crassulaceous spe- cies Kalanchoe linearifolia Drake and K. beharensis African Entomology 12(2): 201–207 (2004) *To whom correspondence should be addressed. Present address: ARC-Plant Protection Research Institute, Private Bag X134, Queenswood, 0121 South Africa. E-mail: witta@arc.agric.za