Bulletin of Insectology 60 (1): 39-47, 2007 ISSN 1721-8861 Efficacy of kaolin, spinosad and malathion against Ceratitis capitata in Citrus orchards Mohamed BRAHAM 1 , Edison PASQUALINI 2 , Neziha NCIRA 3 1 Regional Research Centre in Horticulture and Organic farming, Chott-Mariem, Tunisia 2 Dipartimento di Scienze e Tecnologie Agroambientali - Entomologia, Università di Bologna, Italy 3 Station de Défense des Cultures du Centre, Kalâa Sghira, Tunisia Abstract Field experiments were conducted in 2005 on orange, Citrus sinensis (L.) Osbeck, var. Thomson in two different sites, Sbikha and Sidi Bouali, in Tunisia to assess the effectiveness of kaolin, spinosad and malathion against the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera Tephritidae). In both study sites, the materials were applied 3 times (kaolin at a concen- tration of 5 kg formulated product /100 l, spinosad at a concentration of 1 l formulated product /ha and malathion at a concentra- tion of 200 ml formulated product /100 l). The efficacy of the different treatments was evaluated by assessing male captures in modified Steiner traps and fruit damage (punctured and dropped fruits). The results indicated that (1) no significant differences among treatments in male captures were detected (2) fruit damage (no. punctured fruits and fallen fruits) was lower on kaolin-treated trees than on spinosad, malathion, and untreated trees. Kaolin suc- cessfully protected fruits from medfly infestations and provided long term control, from fruit development until harvest, whereas the insecticide, malathion, and the naturally derived insect control agent, spinosad, failed to protect fruits. Kaolin appears to be an important and helpful tool to reduce medfly fruit damage, and could be a valid alternative to intensive applications of insecticides, currently commonly used in Citrus orchards. Key words: Ceratitis capitata, medfly, kaolin, spinosad, malathion, field trial, Citrus, Tunisia. Introduction The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedeman) (Diptera Tephritidae), is a serious eco- nomic pest infesting more than 350 species of fruits and vegetables throughout the world most of which are of high commercial value (Liquido et al., 1991). In Tunisia C. capitata is a multivoltine species, present all year round and essentially active from May to January on different host plants, such as apricot, peach, fig, plum, apple, pear, and Citrus. The number of generations per year varies with local temperatures and host plant. Fruits attacked by C. capitata can be found in any sea- son in the warm coastal regions. Economically, Citrus is the main host, especially early cultivars like Thomson and Washington navel, but also other Citrus including late cultivars (e. g. Valencia late), and late apricot and peach cultivars (ripening after the second week of May) can show heavy C. capitata infestation levels. The control of the medfly in the main Citrus produc- ing areas in Tunisia (North Eastern regions of the coun- try) is centralized and carried out by the Ministry of Ag- riculture: malathion mixed with a hydrolyzed protein bait (food attractant) is applied in aerial and ground treatments. C. capitata control in other areas and on non-citrus crops, is conducted by the individual farmer with a wide range of different pesticides. Although very effective when correctly applied, bait sprays are known to create ecological, toxicological and environmental problems (Troetschler, 1983). Malathion was found to be highly toxic to a number of beneficial insects, such as honey bees (Gary and Mussen, 1984) and parasitoids (Cohen et al., 1987; Daane et al., 1990), and therefore this active ingredient needs to be replaced with other, less harmful agrochemicals. A possible alternative to malathion for medfly control is spinosad, an insecticide obtained from the naturally occurring actinomycete, Saccharopolyspora spinosa Mertz and Yao, (Dow Agrosciences, 2001). This active ingredient has been combined with a food attractant and feeding stimulant, formulated, and the formulated prod- uct is sold in Tunisia under the brand name Success Ap- pât (Dow Agro sciences, Indianapolis, Indiana, USA). Recent studies show that spinosad is effective in con- trolling medfly infestations (Burns et al., 2001; Vargas et al., 2002). Furthermore spinosad was demonstrated safe to honeybee (Miles, 2003). Kaolin (Surround ® WP, Engelhard Corp. Iselin, NJ, USA) is also a potential alternative pest management product with improved safety and reduced environ- mental impact. Kaolin, is a white non-porous, chemi- cally inert, non-swelling, low-abrasive, and fine grained aluminium-silicate mineral that easily disperses in water (Glenn and Puterka, 2005). Kaolin is used to protect plants from insect pests as well as from sunburn and heat stress (Glenn et al., 1999; Glenn and Puterka, 2005; Melgarejo et al., 2004; Wand et al., 2006). On the plants kaolin forms a particle film altering in- sect/pathogen behaviour on the plant. It can easily be removed from harvested commodities. On plants coated with hydrophobic particle films, repellence, oviposi- tional deterrence, and reduced survival of insects were observed (Glenn et al., 1999; Glenn and Puterka, 2005). The formulated product Surround WP was shown to be effective against different diseases and insects (Glenn et al., 1999; Knight et al., 2000; Saour and Makee, 2003; Mazor and Erez, 2004; Saour, 2005), in particular pear psylla, Cacopsylla pyricola (Foerster) and C. pyri (L.)