Biocontrol News and Information 38(2), 11N–18N www.cabi.org/BNI General News Parasitoids Established for Lily Leaf Beetle in the the states, and further afield to New Hampshire, USA Maine and Connecticut, while T. setifer was shipped to Canada in 2010 for release near Ottawa. Decisions A paper in Environmental Entomology describes a about where to release the different parasitoids were programme leading to the successful establishment based on knowledge of the climate of their native of three parasitoids against the introduced lily leaf ranges in Europe: T. setifer in all release areas beetle (Lilioceris lilii) in North America, which has because it has the greatest likelihood of establishing the potential to mitigate the impact of the beetle’s throughout lily leaf beetle’s potential North Amer- 1 invasion. The authors discuss how a management ican range; L. errabundus in maritime areas; and D. strategy could be optimized from what they have jucunda in northern/inland US locations. Parasitoid learned during the release and monitoring phase of establishment and spread was monitored initially by the project. sampling and latterly by enlisting the gardening public to send in larvae for dissection. All three spe- Lilioceris lilii is found widely in Eurasia and was cies have established in the USA, and T. setifer is introduced to North America in 1943. It is now dis- established in Canada. They have spread from tributed throughout most of the northeastern USA release sites, with rates varying for the species and southeastern Canada, with localized populations between 1–2 and 4–5 km/year. Impact in terms of further west in both countries. Introduction to new reduced beetle populations and lily damage from T. regions and areas has in most cases been via infected setifer and L. errabundus is becoming apparent from bulbs or plants, with ensuing local spread. It is a monitoring results and anecdotally from gardeners’ serious pest of ornamental and native Lilium and reports. Fritillaria species (family Liliaceae) in North America some of which are of conservation status. The authors use their results to illustrate how horti- cultural practices could be amended to support Currently the only other species of Lilioceris present biological control. Pesticide use is generally difficult in North America, L. cheni, was introduced as a bio- to integrate with biological control, and lily bulbs are control agent of air potato (Discorea bulbifera). Three frequently treated with systemic pesticides that are members of the same subfamily are introduced pests not always declared at the point of sale, so organi- that have been largely controlled by introduced par- cally-produced bulbs are recommended. These are, asitoids. No parasitoids or predators of L. lilii had as the authors note, more expensive and can be diffi- been found in North American populations. Taken cult to obtain, which would hamper both scientists together, these factors suggested that classical bio- seeking to establish release plots and gardeners logical control was a good avenue to explore for L. alike. A more-easily integrated change is related to lilii. The area of origin of the lily leaf beetle is mulching strategies. Mulching lilies is a common thought to be China. It was probably introduced to practice among North American (and some Euro- Europe, where it is not a pest either, several hundred pean) gardeners, but during the first US releases it years ago. Published records of natural enemies in was found to prevent T. setifer over-winter survival Europe led to first surveys being conducted in and establishment. While lily leaf beetles fly away to France, and later in other climatic zones. Beetles on seek suitable overwintering sites, the three parasi- ornamental and especially native lilies were found to toids overwinter in host cocoons underneath lily be heavily parasitized, usually by several species, plants, and a layer of mulch may give inadequate although the dominant species varies with region. protection from low temperatures, desiccation and predation. Equally, autumn disturbance of lily bulbs Seven parasitoid species were collected during sur- (moving or lifting in autumn and replanting in veys and, after initial screening by CABI in spring) can interfere with the parasitoid life cycles. Switzerland, four of them were sent to the University of Rhode Island (URI), USA. Further host-specificity A larger problem is the slow rate of spread of the par- testing in quarantine eliminated one of the species. asitoids, attributable at least in part to the patchy Proposals for field release of the remaining three spe- distribution of both cultivated and native lilies. As cies as biocontrol agents for L. lilii were approved by the authors discuss, a programme of laboratory and USDA-APHIS-PPQ (US Department of Agriculture field-plot rearing and redistribution of three parasi- – Animal and Plant Health Inspection Service – toids was very successful against the related cereal Plant Protection and Quarantine) and relevant US leaf beetle (Oulema melanopus) in the 1970s, but O. states. melanopus was recognized as a major threat to agri- culture and received substantial funding and The eulophid Tetrastichus setifer and two ichneumo- staffing. Lily leaf beetle funding will be much more nids, Lemophagus errabundus and Diaparsis limited. Ensuring that the parasitoids are deployed jucunda, were released from 1999 and 2003, respec- to best effect as the lily leaf beetle invasion expands tively, in monitored plots in Rhode Island and will be a real challenge. However, results from Massachusetts. Once establishment was docu- releases of the three agents have led the authors to mented, the parasitoids were redistributed within conclude that releases can be quite modest in Are we on your mailing list? Biocontrol News and Information is always pleased to receive news of research, conferences, new products or patents, changes in personnel, collaborative agreements or any other information of interest to other readers. If your organization sends out press releases or newsletters, please let us have a copy. In addition, the editors welcome proposals for review topics. 12N Biocontrol News and Information 38(2) number, and are most effective on reasonably sized, Southeast Asia revealed two more interesting bra- well-infested lily plots. Parasitoids are also likely to conid species, Phanerotoma syleptae (an egg–larval establish more easily on wild lilies (in Europe, para- parasitoid) and Therophilus javanus (a larval parasi- sitism levels are higher on wild lily populations). toid), with field parasitism rates of up to 60%.8 Both Wild lilies in the invaded range stand a good chance parasitoids were introduced from the World Vege- of harbouring parasitoid populations, which could table Center (WorldVeg) to the rearing labs of the reduce damage and contain outbreaks better, and International Institute of Tropical Agriculture this would be good news for North America’s threat- (IITA), Benin Station, for two years’ confined testing. ened and endangered lily species. An interesting aspect worth mentioning is that, by the time we introduced the parasitoids in our labs, Modelling suggests that much of the North American we had just switched from rearing M. vitrata larvae continent is suitable and therefore under threat from on artificial substrate to the use of sprouted cowpea the lily leaf beetle. Establishment of a suite of three grains as a natural substrate. As we found out later, biocontrol agents while the invasion is still in its we would never have been able to establish a rearing early stages could be a key factor in slowing the colony for one of the parasitoids, T. javanus, if we had pest’s spread and limiting the impact of the invasion tried to rear it on M. vitrata larvae originating from in new areas. This early research will also be invalu- artificial diet, possibly because of a lack of essential able in guiding release strategies as the parasitoids elements, or because of the presence of some anti- are redistributed in North America to counter the nutritional factors affecting the development and invasion. survival of the parasitoid. 1 Tewksbury, L., Casagrande, R.A., Cappuccino, N. Once we had obtained release permits from the and Kenis, M. (2017) Establishment of parasitoids of respective national authorities, a total of 101,600 the lily leaf beetle (Coleoptera: Chrysomelidae) in adult parasitoids – 60,100 in Benin (30,300 T. North America. Environmental Entomology. javanus and 29,800 P. syleptae) and 41,500 in DOI:10.1093/ee/nvx049. Burkina Faso (23,000 T. javanus and 18,500 P. syleptae) – were released, starting in January 2016. Contact: Lisa Tewksbury, Based on ecological observations in their native area University of Rhode Island, USA. in Southeast Asia, our release strategy targeted dif- Email: [email protected] ferent agro-ecologies and host plant habitats depending on the parasitoid species. For P. syleptae, we released on flowering legume trees and shrubs Towards Successful Establishment of Exotic such as Pterocarpus santalinoides, Lonchocarpus Parasitoids Attacking the Pod Borer Maruca sericeus, Philenoptera cyanescens (syn. L. cyanes- vitrata in West Africa cens) and Milletia thonningii, all belonging to the family Leguminosae–Papilionaceae. These plants The legume pod borer, Maruca vitrata (Lep., Cram- are major hosts for Maruca vitrata populations bidae; syn. M. testulalis), remains the single most during the off-season, when no cowpea is planted.9 In important insect pest attacking cowpea (Vigna contrast, T. javanus was released on cowpea crops unguiculata) and other leguminous crops and wild and patches of herbaceous legumes including Ses- species in Africa. The damage caused by M. vitrata bania rostrata, Tephrosia platycarpa and Pueraria caterpillars feeding on flowers and pods of cowpea is phaseoloides, all Leguminosae–Papilionaceae, as estimated at 20–80%, depending on agro-ecological well. Releases were carried out with the active par- zone and climatic factors.1 ticipation of local communities and were preceded by a sensitization campaign explaining in simple terms For many years, this pest was tacitly categorized as the concepts of biological control.