Aspects of the Biology, Distribution, and Host Range of Crioceris sp. (Col.: Chrysomelidae: Criocerinae), a Potential Biological Control Agent for Asparagus asparagoides in Australia A. B. R. Witt 1 and P. B. Edwards CSIRO Biological Control Unit, Zoology Department, University of Cape Town, Private Bag, Rondebosch 7700, South Africa Received September 20, 2000; accepted September 4, 2001 Aspects of the biology, distribution, and host range of Crioceris sp. (Chrysomelidae: Criocerinae), a poten- tial biocontrol agent for Asparagus asparagoides (L.) W. Wight (bridal creeper) in Australia, were ascer- tained from studies in its native range in South Africa. In the laboratory, adults oviposited on new growth of A. asparagoides within 10 days of emergence and laid an average of 148 eggs per female. Eggs maintained at 15, 20, and 30°C eclosed after 8.7, 5.1, and 3.6 days, respectively. Larvae passed through four instars, with the final instar constructing a pupal case in the soil. Only 29% of adults from laboratory cultures emerged from dry pupal cases after an average of 75.9 days. Submerging pupal cases in water for short periods greatly enhanced adult emergence. Adults can live longer than 6 months. Crioceris sp. was mainly found on A. asparagoides and A. densiflorus/aethiopicus in winter-rainfall and even-rainfall areas. Larval and adult specificity testing indicated that this species could complete its development only on species within the Asparagaceae. Crioceris sp. is therefore a promis- ing candidate for the control of A. asparagoides in Australia. © 2002 Elsevier Science Key Words: Asparagus asparagoides; Crioceris sp.; biological control; bridal creeper; weeds. INTRODUCTION Bridal creeper (Asparagus asparagoides (L.) W. Wight; Asparagaceae) is native to southern Africa and was introduced into Australia as an ornamental plant in the 1800s (Scott, 1995). It has subsequently invaded large tracts of land in southern Western Australia, South Australia, Victoria, and southern and central New South Wales (Raymond, 1995) and is currently regarded one of the most serious environmental weeds in the region (Humphries et al., 1991). It threatens the conservation value of many areas since it can com- pletely dominate the understory and has the potential to affect the regeneration of native species and alter the composition and structure of the plant community (Raymond, 1995). Mechanical and chemical control have proven to be impractical and expensive since each plant has a rhizome which bears numerous fusiform tubers that form dense mats underground. An undescribed leaf beetle, Crioceris sp. (Chry- somelidae: Criocerinae), was found feeding on A. as- paragoides at various localities in the Western Cape Province, South Africa (Scott and Kleinjan, 1991). Chrysomelids have been used extensively for the con- trol of invasive plants. Forty-seven species have been introduced for biological control with 16 of these hav- ing exerted some level of control (Syrett et al., 1996). A study was therefore undertaken to determine the dis- tribution, biology, and host range of Crioceris sp. in South Africa. MATERIALS AND METHODS Biology Rearing. Larvae of Crioceris sp. collected at Nacht- wacht farm (34°35'S 20°07'E) near Bredasdorp in the Western Cape Province of South Africa were used to start a laboratory colony, which was maintained at 23  2°C and 50  10% relative humidity. Larvae were placed in ventilated containers on bouquets of fresh new growth from potted A. asparagoides plants. The bouquets were replaced every 3 days. The bottoms of the containers were covered in a 1-cm layer of potting soil in which larvae could pupate. Containers with pupal cases were retained in the laboratory, under natural photoperiod. For egg production studies, adult pairs were placed on fresh sprigs in ventilated contain- ers and eggs were removed every 24 h. 1 To whom correspondence should be addressed at current ad- dress: South African Field Station, Queensland Department of Nat- ural Resources and Mines, c/o PPRI, P/Bag X134, Pretoria, 0001, South Africa. Fax: (012) 3293278. E-mail: rietaw@plant2.agric.za. Biological Control 23, 56 – 63 (2002) doi:10.1006/bcon.2001.0991, available online at http://www.idealibrary.com on 56 1049-9644/02 $35.00 © 2002 Elsevier Science All rights reserved.