~ 246 ~  Journal of Entomology and Zoology Studies 2015; 3(6): 246-249 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2015; 3(6): 246-249 © 2015 JEZS Received: 23-09-2015 Accepted: 26-10-2015 Abir Hafsi a) High Agronomic Institute of Chott-Mariem, University of Sousse, 4042 Chott-Mariem, Sousse, Tunisia. b) CIRAD, UMR 53 Peuplements Végétaux et Bioagresseurs en Milieu Tropical, Cirad/Université de La Réunion, 7, chemin de l’IRAT, 97410 St-Pierre, La Réunion, France Khaled Abbes High Agronomic Institute of Chott-Mariem, University of Sousse, 4042 Chott-Mariem, Sousse, Tunisia. Ahlem Harbi a) High Agronomic Institute of Chott-Mariem, University of Sousse, 4042 Chott-Mariem, Sousse, Tunisia. b) Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetaly Biotecnología, Unidad Asociada de Entomología UJI-IVIA. Moncada, Spain. Ridha Rahmouni a) High Agronomic Institute of Chott-Mariem, University of Sousse, 4042 Chott-Mariem, Sousse, Tunisia. b) Centre Technique Des Agrumes Rte De Béni Khalled, Km 6, Zaouiet Jédidi, Tunisie Brahim Chermiti High Agronomic Institute of Chott-Mariem, University of Sousse, 4042 Chott-Mariem, Sousse, Tunisia. Correspondence Brahim Chermiti Institut Supérieur Agronomique de Chott-Mariem, laboratoire d’Entomologie et de Lutte Biologique, Université de Sousse, 4042, Sousse, Tunisie Comparative efficacy of Malathion and spinosad bait sprays against Ceratitis capitata Wiedmann (Diptera: Tephritidae) in Tunisian citrus orchards Abir Hafsi, Khaled Abbes, Ahlem Harbi, Ridha Rahmouni, Brahim Chermiti Abstract Malathion is the key insecticide used in the control of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) in Tunisia. Resistance to this organophosphate insecticide has been reported in various insect species. The use of Malathion will slowly phase out and replaced by more environment friendly insecticides such as spinosad. In this study, we evaluated spinosad as a replacement of Malathion in bait spray to control C. capitata in Tunisian citrus orchards. The assessment was based on weekly monitoring of C. capitata males catches in traps baited with trimedlure and the estimate of fruit damage on the Maltaise variety. Our results showed that the population level was significantly lower in spinosad than in Malathion bait sprays with 1.6 and 15.30 fly/trap/day respectively. The effectiveness of spinosad treatment was confirmed by significantly low rates of fruit damage not exceeding 9.75 %. Keywords: Citrus, Mediterranean fruit fly, Malathion, Spinosad, bait spray Introduction In Tunisia, citrus fruits are an important and valuable export commodity. Citrus culture is particularly important in the region of Cap Bon in North-eastern Tunisia. It is the main production area with about 15300 ha of citrus orchards [1] Tunisian citrus sector is restrained by several problems. Among these, the Mediterranean fruit fly (medfly) Ceratitis capitata Wiedemann is the most economically important insect pest among Tephritidae fruit flies which are well known for having economical importance since they affect a wide range of cultivated fruits [2] . In Tunisia, the economic damage caused by the medfly is estimated to be about 6.16 million USD [3] . Actually, the control of this pest remains problematic considering the severity of the caused damage. In the last decades, many control techniques have been developed and implemented to manage the medfly including male annihilation, sterile male and chemical control with insecticide- baited protein hydrolysate. In Tunisia, most of the currently applied control schemes are mainly based on frequent applications of organophosphate based insecticides, especially Malathion mixed with protein-based baits (Lysatex) [4] . Malathion aerial sprays are very common. They are exclusively carried out by the Tunisian Ministry of Agriculture mainly during the period from September to November with an average of 3 sprays. Besides, many additional ground-malathion treatments can be performed by the farmers [5] . Resistance to Malathion has been reported in many insects’ pests, including some dipteran pests [6] and C. capitata populations in Spain [7] . These insecticides have been found to have negative impacts on beneficial insects [8, 9] and can result in secondary outbreaks of other pests [10] .The use of malathion will slowly phase out and replaced by more environment friendly insecticides such as Spinosad which may reduce insecticide residues in citrus fruit [11] . This insecticide has a better environmental profile and is less toxic to natural enemies compared to malathion [12, 13, 14] and showed a good control of different Tephritid pests worldwide [15, 16] . The aim of this study is to evaluate spinosad as a replacement for Malathion in bait spray to control C. capitata with regard to two parameters: monitoring of C. capitata populations and evaluation of fruit damage in Tunisian citrus orchards. Materials and methods Field sites The study was conducted in citrus orchards planted with Maltaise variety from October to December 2011in three orchards located in the Cap Bon region, Tunisia in order to assess