Biological control of Tuta absoluta in Argentina and Italy: evaluation of indigenous insects as natural enemies M. G. Luna 1 , N. E. Sa ´ nchez 1 , P. C. Pereyra 1 , E. Nieves 1 , V. Savino 1 , E. Luft 2 , E. Virla 2 and S. Speranza 3 1 Centro de Estudios Parasitolo´gicos y de Vectores (CEPAVE) CONICET & UNLP, La Plata, Argentina; e-mail: lunam@cepave.edu.ar 2 PROIMI – Biotecnologı´a, Div. Control Biolo´gico. CONICET, Tucuma´n, Argentina; e-mail: evirla@gmail.com 3 Department of Agriculture, Forests, Nature and Energy, University of Tuscia, Viterbo, Italy 3 ; e-mail: speranza@unitus.it By means of an international project, Argentinian and Italian researchers are carrying out joint research to study biological and ecological aspects of Tuta absoluta biological control. This paper lists indigenous natural enemies reported for T. absoluta, as well as the current results on T. absoluta egg and larval parasitoids in both countries. Parasitoid species that conformed to different guilds are shown to coexist in cropping conditions, and some show positive characteristics as potential biocontrol agents against T. absoluta by means of aug- mentative releases. Future laboratory and field evaluations of effective biological control programmes in Argentina and Italy are proposed. Introduction The tomato moth Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a key pest of tomato originating from South America, present in all cropping regions of both Italy and Argentina. In Argentina it was first recorded in 1964 (Bah- amondes & Mallea, 1969). Four decades later, T. absoluta was detected in Spain (in 2006), and from this point of introduction it spread rapidly throughout the Mediterranean basin countries becoming a serious tomato pest (Desneux et al., 2010). In Italy, T. absoluta was detected in 2008 (Viggiani et al., 2009). Currently it is dispersing to other European and Middle East Asian states, and it is predicted that in a 15-year period it will reach the Pacific Asian Coast (Desneux et al., 2011). Tomato is an important horticultural product in both countries. In Argentina, it reaches 17 000 ha, mostly under open cropping although protected crops have increased con- siderably during recent decades. The main tomato produc- tion regions are: Cuyo (310 000 tonnes), Northwestern (260 000 tonnes), Northern Buenos Aires (100 000 tonnes) and Northeastern (70 000 tonnes) (Argerich, 2011). In Italy, tomato is cultivated all over the country, reaching 19 314 ha and 600 000 tonnes of production per year. Sicilia, Campania, Abruzzo, Lazio Calabria and Sardinia are the main cultivation regions, representing 75% of Italian production. Tuta absoluta is a multivoltine species in both countries, which rapidly develops in favorable environmental condi- tions, with up to nine overlapping cycles per year in the south of Italy and 12 in Argentina (Guenaoui et al., 2010; Sannino & Espinosa, 2010a,b). Females lay 100–200 eggs on the upper part of the plant. The newly hatched larvae dig mines in the leaf parenchyma, where they reside until the fourth-instar larval stage. Pupation takes place on the plant or in the soil, sometimes protected by a silky cocoon. Tuta absoluta does not have a winter diapause. The pest attacks tomato leaves, stems and fruits, and it is considered as oligophagous because it prefers mostly solanaceous spe- cies as host plants. Moreover, it can lead to secondary infestations. The mean population reproductive rate (R o ), when fed on tomato (its preferred host), is threefold greater than on other solanaceous crops such as potato However, its ability to feed on other host plants can enhance the capacity of T. absoluta to adapt to different environmental conditions, which confers an important invasive behaviour on this pest (Pereyra & Sa ´nchez, 2006). Tuta absoluta control in Argentina is based mostly on the use of synthetic pesticides. More than 16 neurotoxic insecticides are applied on a weekly basis, up to 14 times per growing cycle (Strassera, 2009). In this country there are also studies in progress to evaluate the use of Bacillus thuringiensis- and azadirachtin-based products to be com- bined in integrated pest management (IPM), mostly targeted to preserve the whiteflies’ parasitoid Eretmocerus mundus (Ca ´ceres et al., 2011). In Italy, chemical control is also applied heavily through weekly calendar treatments in greenhouses and open-field crops. However, IPM strategies are starting to be applied based on monitoring with phero- mone traps followed by chemical or natural pesticides treat- ments (Speranza & Sannino, 2011). Because of the concealed (within-leaf) feeding behaviour of T. absoluta larvae, chemical control may be inefficient. Thus tomato producers on both continents commonly have to increase pesticide use as the season progresses, which may lead to an increase of around 70% of total pest 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 ª 2012 The Authors. Journal compilation ª 2012 OEPP/EPPO, EPPO Bulletin 42, 1–8 1 E P P 2 5 6 4 B Dispatch: 9.6.12 Journal: EPP CE: Vinothkumar P. Journal Name Manuscript No. Author Received: No. of pages: 8 PE: Amudhapriya