Tropentag, September 11 - 13, 2024, Vienna "Explore opportunities... for managing natural resources and a better life for all"

The impact of soil management, agroecological zone, and season on ground-dwelling insect diversity in Tunisian olive groves

¹Olive Institute (IO), Tunisia
²BOKU University, Dept. of Crop Sciences, Austria
³Leibniz Inst. for Agricultural Engineering and Bioeconomy (ATB), Agromechatronics, Germany
⁴Natural Resources Institute Finland (LUKE), Finland

Abstract

In conventional farming system, Tunisian olive groves are usually managed intensively to optimise yields, without considering possible negative impacts on biodiversity. Agroecology for sustainable olive growing recommends several practices to counter this oversight, such as no tillage or cover crops. In this study, insect diversity was assessed in two olive groves, each located in a different agroecological zones (AEZ): Toukaber in Beja Governorate, and Jammel in Monastir Governorate. Three soil management practices were tested: Tillage, No tillage, and Faba bean cover crop, with three replicates in Toukaber olive grove and five in Jammel. Sampling was carried out in 2022 using eight pitfall traps per replicate at two periods: olive flowering and fruit ripening. Our study showed that the number of insect orders was higher in Toukaber than in Jammel with 15 vs. 12 orders during flowering and 15 vs. 11 orders during fruit ripening, respectively. In Jammel, the most abundant order was Collembola (43.65%), found during olive flowering in the practice of Faba bean cover crop. Collembola may, therefore, be positively affected by the companion crop. During fruit ripening, Hymenopteran insects were the most abundant in no tillage (66.66%) due to the dominant ants’ activity. In Toukaber, Hemiptera was the most abundant during flowering in the tillage practice (28.09%) and Hymenoptera was the most abundant in Faba bean cover crop (68.02%). The latter practice seemed to promote wasps and pollinating insects. Based on Shannon index values, insect diversity was higher in No tillage during flowering and in Faba bean cover crop during fruit ripening. In addition, tillage seemed to have a negative effect on insect diversity in both seasons for the two AEZs. It can be concluded that the transition to agroecology, by reducing tillage and introducing cover crop, can contribute to the enhancement of insect diversity in olive groves.

Keywords: Agroecosystem, biodiversity, intercropping, orchard

Contact Address: Amel Ben Hamouda, Olive Institute (IO), Sousse, Tunisia, e-mail: benhamoudaayedamelgmail.com