10 th International Working Conference on Stored Product Protection Julius-Kühn-Archiv, 425, 2010 735 Insecticidal effect of anisaldehyde against Acanthoscelides obtectus and Callosobruchus maculatus (Coleoptera: Bruchidae) Ndomo, A.F. 1,2,3 #, Tapondjou, L.A.* 1 , Tchouanguep, F.M. 2 1 University of Dschang, Department of Chemistry, Faculty of Science, Laboratory of Applied and Environmental Chemistry, P.O. Box 183, Dschang, Cameroon. Email tapondjou2001@yahoo.fr 2 University of Dschang, Faculty of Science, Department of Biochemistry, Laboratory of Medicinal plants, Science and Nutrition, P.O. Box 67, Dschang, Cameroon 3 Julius Kuehn-Institut, Federal Research Centre for Cultivated Plants/ Institute for Ecological Chemistry, Plant Analytics and Stored ProductProtection, Königin Luise Straße 19, 14195 Berlin, Germany * Corresponding author # Presenting author DOI: 10.5073/jka.2010.425.316 Abstract In the present study, anisaldehyde, a compound found in the essential oil of Clausena anisum-olens, was tested for its insecticidal activities against Acanthoscelides obtectus and Callosobruchus maculatus. The amounts of anisaldehyde applied were 0, 0.5, 1, 2 and 4 μL diluted in 1mL of acetone and applied to 40 g of either beans or cowpeas corresponding to the doses of 0, 0.008, 0.016, 0.033 and 0.066 μL/g of seed. Additionally, adsorbent clay was used as a carrier of this product in order to increase the persistence of its insecticidal activity over time. This clay was mixed with the aforementioned volumes of anisaldehyde to form a powder formulation. Furthermore, to assess the insecticidal effect over time, the F 1 progeny production was also evaluated. These two products caused significant mortality in the two tested insects. Nevertheless, C. maculatus was more susceptible than A. obtectus at tested doses. The progeny production decreased with the increasing doses of anisaldehyde and ACP with 0 % at the highest dose (0.066 μL/g). According to the LD 50 , LD 95 and their confidence intervals, the toxicity of ACP was significantly different (P<0.05) to anisaldehyde at the tested doses towards A. obtectus adults. However, there was no significant difference observed between the effects of these two products towards C. maculatus. These preliminary results suggest that anisaldehyde and ACP could be used in stored-product protection, but this needs further research. Research is also needed to determine its toxicity on rats in order to assess its potential hazards for workers and consumers. Keywords: Anisaldehyde, Clay, Contact toxicity, Bruchids 1. Introduction Cowpea (Vigna unguiculata (L.) Walpers) and beans (Phaseolus vulagris (L.) (Fabacaea) are important crops for many subsistence farmers in the tropics, especially in Africa, because they contain a high level of protein (20 to 25% and 23 to 30% respectively), and are used as human food (Broughton et al., 2003). In tropical and subtropical countries, dry and ripe seeds of these legumes are currently destroyed by Callosobruchus maculatus (F.) and Acanthoscelides obtectus (Say) (Coleoptera: Bruchidae), respectively (Delobel and Tran, 1993). Physical, biological and chemical methods have been developed in order to control stored-product insects. In addition, plants extracts (essential and vegetable oils, organic and aqueous extracts) have insecticidal, fungicidal and bactericidal properties (Boeke et al., 2001, Kuiate, 1993). As an insecticide, plant extracts can acts as a contact insecticide, fumigant, and antifeedant or as a repellent (Boeke et al., 2001). Some constituents of essential oils are insecticidal (Boeke et al., 2001; Hinman, 1954; Burditt et al., 1963; Hammond et al., 2000) and may inhibit growth of insects (Huang et al., 2002). On the other hand, some clays are recognised by some traditional societies for their ability to control insects (Ramaswamy et al., 1995). The use of such powders, aromatised with essential oils or insecticidal pure compounds could have a combined effect of mechanism action and insecticidal action (Ramaswamy et al., 1995; Ndomo et al., 2008).