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Plant Protection Quarterly Vol.15(1) 2000 21 belonging to eight orders were found feeding on the plant (Figure 2, Table 2). The insect fauna associated with horehound The insects included 12 polyphagous spe- (Marrubium vulgare L.) in western Mediterranean cies (44%), 8 oligophagous species (30%) and 7 monophagous species (26%). At the Europe and Morocco: potential for biological control larval stage, there were five root-feeding in Australia species (22%), one stem-boring species (4%), nine leaf-feeding species (39%), eight flower, ovary or seed feeding species A Jean-Louis Sagliocco , Keith Turnbull Research Institute, Victorian (34%). Based on adult feeding behaviour Department of Natural Resources and Environment, CRC for Weed there was one root-boring species (74%), Management Systems, PO Box 48, Frankston, Victoria 3199, Australia. six leaf-feeding species (40%) and eight A Previous address: CSIRO European Laboratory, Campus International de species feeding on flowers or ovaries or Baillarguet, 34980 Montferrier sur Lez, Cedex, France. seeds (53%). Wheeleria spilodactylus (Curtis) Summary were preserved. Immature stages were (Lepidoptera: Pterophoridae) Marrubium vulgare L. (Lamiaceae) was kept with fresh plant material until the Wheeleria spilodactylus was abundant at surveyed in western Mediterranean Eu- adult stage for identification. Insects most sites in France and Spain, and had rope and Morocco to identify the phy- were observed either in the field or the been recorded feeding on M. vulgare tophagous insect fauna associated with laboratory to confirm that they fed on the (Gielis 1996) and Ballota nigra (Bigot and this weed and to select species having plant. Insects were sent to museum spe- Picard 1983). The insect’s distribution in- some potential as biological control cialists for identification and literature cludes Western and Continental Europe, agents. Twenty-seven insect species searches were conducted to assess their British Islands, the Mediterranean region, were found to feed on the plant. Two plant host-range. Selection of candidate Asia Minor and Northern Africa (Savela Lepidopteran species have been intro- biological control agents was based on 1999a). Females lay eggs underneath the duced into Australia to control the weed. their supposed degree of specificity, their leaves and the green larvae feed on leaves, Five additional species (three Lepidop- known host-plants from the literature and stems and tips of shoots, often causing tera and two Coleoptera) are considered feeding behaviour. Priority was given abortion of buds, and pupae can be found as potential candidates for introduction to insects having the strongest observed on leaves. It was the first candidate insect and host-specificity tests. impact on plants, either through plant to be considered for the biological control biomass reduction (in the case of larvae of horehound. A first consignment of lar- Introduction feeding on leaves) or through reduction in vae originating from Cap d’Agde, Herault Marrubium vulgare L. (Lamiaceae) is an in- the plant’s reproductive capacity. (43°32’N, 003°51’E) was sent to Keith vasive weed of pastures and natural habi- Turnbull Research Institute, Frankston, in tats in southern Australian states. The ge- Results 1991 for host-specificity tests, and subse- nus Marrubium comprises of 48 species, all Insect abundance quently M. vulgare was shown to be the originating from Eurasia (Seybold 1978). Significant populations of M. vulgare were preferred host-plant of the insect (J. Weiss In Europe the genus Marrubium includes found on calcareous soils with little or unpublished data). W. spilodactylus was twelve species (Tutin et al. 1972). M. no plant competition and with occa- released at many sites in Victoria and at vulgare L., an erect perennial herb, is the sional or regular grazing by sheep. In six Wyperfeld National Park in 1994 (Weiss most common species being present in all countries 55 M. vulgare populations were 1996) and later in South Australia, ACT regions but the most northern countries. examined (Table 1), and 27 insect species and Tasmania (Wills 1998). To tackle M. vulgare is also common in north Africa (Parsons and Cuthbertson 1992). It is found mostly on well-drained calcareous soils and is more common on lands where grazing occurs. In this paper, I present the results of surveys for phytophagous insects that could be used as biological control agents against M. vulgare in Aus- tralia. Methods Horehound populations were regularly surveyed around Montpellier, southern France. Plants were randomly collected and taken to the laboratory for measure- ments and dissection. Outside of France, searches were conducted in regions with suitable alkaline soils and climate, with searches mostly done along roadside populations and on lands close to roads. Surveyed countries were Spain, Portugal, Morocco in 1991–97 with minor searches made in Italy and the former Yugoslavia in 1991 (Figure 1). Plants were randomly collected and dissected in the field. Adult Figure 1. Marrubium vulgare L. populations surveyed in western Europe and insects found on plants or after sweeping Morocco. 22 Plant Protection Quarterly Vol.15(1) 2000 climatic differences occurring within the Meligethes spp. and Meligethes rotroui country. Easton (1952) concluded from his horehound distribution in southern Easton (Coleoptera: Nitidulidae) observations, as well as from the general Australia, a second biotype of W. spilo- The Meligethes genus in Europe comprises literature on Meligethes, that these four dactylus originating from regions of Spain about 125 species (Schenkling 1913). East- species were very likely to be specific to with long dry summers, was imported on (1955) clarified the taxonomic position horehound. M. rotroui seems to be the best into Australia in 1996. of the north African species within this adapted to the dry and warm regions of group. Four species have been described Australia because of the climate in the re- Carcharodus boeticus Rambur as associated with horehound (Easton gions where it occurs in Morocco. Like the (Lepidoptera: Hesperiidae) 1952), but the small size of insects and the three other Meligethes species mentioned Carcharodus boeticus was common in small taxonomic features used for identifi- above, M. rotroui overwinter as adults and France and Spain where it was found at cation make the sorting of species difficult in Morocco becomes active on horehound most of the sites. According to Rungs and uncertain. Both adult and larval stages plants when flowers are first produced, in (1979) this species is absent from Morocco. feed on M. vulgare flowers and pollen and March. Adults feed on the flowers espe- In France, adults were observed flying in destroy significant numbers of seeds. cially on pollen and anthers. After suffi- April, June and September and larvae The distribution of M. nanus in France cient food intake they become sexually have been recorded on M. vulgare and extends from the Perpignan region to Pro- mature, mate and lay eggs on the flower Ballota foetida Lamk. (Lhomme 1935, vence Easton (1951), and the species is also clusters. Larvae hatch and develop in the Savela 1999b). Larvae are nocturnal and found in Spain (Schenkling 1913). M. calyxes, feeding on pollen and ovaries, feed on horehound leaves, hiding during tropicus occurs in southern France, Spain moving from flower to flower to complete the day in a nest made with rolled leaves and along the coastal areas of North Af- their development. Gradually, adults spun with silk. This species was consid- rica (Reitter 1919), while the distribution from the previous generation die, and ered to be a potential agent for horehound of M. villosus extends from Germany to fully developed larvae pupate in the soil and sent to quarantine in Australia in 1994 Morocco. The species M. rotroui was de- litter at the base of plants in April. In May, and 1995. However the introduction was scribed by Easton (1952) after close exami- adults of the new generation can be found unsuccessful due to difficulties in obtain- nation of specimens from Morocco, ini- on plants were they feed until early June, ing matings in quarantine. No further at- tially identified as M. villosus or M. trop- before they disperse, probably into the tempt has been made with this species. icus. His conclusion was that M. villosus woodlands where they aestivate during was the commonest species to occur in this the dry summer. Chamaesphecia mysiniformis (Boisduval) (Lepidoptera: Sesiidae) Table 1. Countries and number of Marrubium vulgare populations surveyed. Chamaesphecia mysiniformis was found in northern Spain, around Zaragoza Country Years No. M. vulgare No. insect species (Aragon Province) where the largest hore- populations found hound populations occur. According to France 1991–97 15 24 Lastuvka and Lastuvka (1995) and Leraut Spain 1991–97 20 18 (1997) the insect is present in France but Portugal 1991–92 2 4 was not found during this study. In Mo- Italy 1991 5 2 rocco its status is not clear. Rungs (1979) Former Yugoslavia 1991 2 7 does not mention it, while Savela (1999c) Morocco 1993–97 11 11 reports its presence, but it was not found in Morocco during this study. C. mysini- Total – 55 – formis has one generation per year, fe- males laying eggs at base of plants in June 30 in Spain. Larvae develop in roots of ma- nCandidate candidate agents ture plants generally causing death of the nPolyphagous polyphagous insects plant, sometimes before the adult emer- allAll insects insects gence, or during the following year. Due 25 to the damage observed in the field, and its probable host-specificity, this species was considered to have a strong potential 20 as a biological control agent. Biology and host-specificity of the insect were studied at CSIRO European Laboratory (Sagliocco 15 and Coupland 1995) and approval was given by the Australian Quarantine and No. of species Inspection Service and Environment Aus- 10 tralia to import C. mysiniformis as eggs into quarantine in 1995.

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