Arthropods diversity associated with irrigated rice protected with biopesticides in Western Burkina Faso

---

Résumé

Rice stem borers constitute a serious threat to rice production in Burkina Faso. Trials were conducted in 2022 and 2023
at Bama and Karfiguéla, western Burkina Faso. The study aimed at assessing the biodiversity associated with rice Lepidoptera stem
borers when using biological insecticides for the control of these insect pests. Methods: A randomized completely block design with six
treatments and four replications was used. Treatments included two botanical insecticides (Azadirachta indica, Jatropha curcas), two
entomopathogens (Bacillus thuringiensis, Trichoderma sp.) followed by an untreated control and, a positive control (deltamethrin). Six
insecticide applications per treatment were carried out at a frequency of 14 days each, starting on the 15th day after transplanting (DAT).
Oil extracts from A. indica, J. curcas, and B. thuringiensis, as well as deltamethrin, were applied to the rice plants, while Trichoderma sp.
was applied directly to the soil. Arthropod specimens were caught weekly, from the 14th to the 84 DAT using sweep net and pitfall traps.
Results: Results revealed that the highest arthropod catches were recorded during the 2022 wet season. Regardless of study site and
season, predators were grouped into seven orders, while parasitoids were observed in two orders in the 2022 wet season and a single
order in the 2023 dry season. Parasitoids were mainly Hymenoptera, while predators were dominated by spiders. The highest proportions
were recorded in plots treated with A. indica oil. The highest diversity and distribution of natural enemy species was reached out with
A. indica. Conclusions: These results show that the use of A. indica oil is compatible with the conservation of natural enemies associated
with Lepidoptera rice stem borers

Mots-clés

rice, Lepidoptera stem borers, biopesticides, biodiversity, natural enemies, Burkina Faso