Promising native bio-controllers for sustainable pest management in Argentinean rice fields

FUENTES RODRÍGUEZ, D.; GERVAZONI, P.; TOLEDO A.; MULIERI, P. ; AQUINO, D. ; FRANCESCHINI, C.; SOSA, A.

Simposio; V Simposio Chileno de Control Biológico; 2022

Agricultural productivity and sustainability can be positively influenced by the use of indigenous biodiversity for pest management. Among the most widely used biota for pest biocontrol worldwide, entomopathogenic fungi and parasitoids stand out. However, due to the concerns of regulatory agencies about the importation of alien organisms and their safety to non-target species, it’s important to search native natural enemies for incorporation into sustainable management programmes. This work is aimed at carrying out a bioprospecting to find potential pest bio-controllers in Argentine rice paddies, focusing on parasitoids (Diptera/Hymenoptera) and entomopathogenic fungi (Hypocreales). We surveyed stink bug pests (adults and eggs), and parasitoid insects during the rice growing season. Also, we measured under laboratory conditions, the impact of natural enemies on the stink bugs pests Tibraca limbativentris and Oebalus poecilus (Hemiptera: Pentatomidae). As a result, we collected 304 individuals of Hymenoptera and Diptera (7 families each), finding 11 species of native parasitoids. The most abundant were Telenomus sp. (24.2% of all Hymenoptera collected), Scelio sp. (22.6%), and Sepedonea sp. (9.4% of all Diptera collected). In laboratory, 340 individuals of T. limbativentris and 319 of O. poecilus were tested, and the incidence of natural enemies was recorded in 166 of them. We identified 3 species of entomopathogenic fungi, highlighting the impact of Metarhizium anisopliae on T. limbativentris (24.9% infected individuals). We also detected 3 species of dipteran parasitoids on adult stink bugs, recording Beskia aelops on the two pest species. In addition, 1331 eggs of these pests were tested, of which 311 were parasitized by Telenomus sp. In total, 7 potential bio-controllers were detected in tests, showing different impact concerning the evaluated pests. This shows that there is a natural pest regulation by natural enemies, even under the stress conditions to which the agroecosystem is subjected to the use of agrochemicals. These results establish a basis for future laboratory testing on these native bio-controllers to measure their effectiveness for pest control in rice fields.