Impact of entomopathogenic fungi on stink bug pests in Argentinean rice crops

FUENTES RODRÍGUEZ, D.; TOLEDO, ANDREA; GERVAZONI, PAULA B.; BERTUCCI, SABRINA; SOSA, A.J.; FRANCESCHINI M. CELESTE

Chillan

Simposio; V Simposio Chileno de Control Biológico; 2022

Instituto de Investigaciones Agropecuarias (Chile)

Stink bugs (Hemiptera: Pentatomidae), comprise nearly 900 genera and 5,000 speciesworldwide. Species included in this family are mainly phytophagous and many of them causeenormous economic damage to crops worldwide by feeding on different parts of plants. InNeotropical rice crops,the rice stem stink bug TibracalimbativentrisStål, is one of the mostdifficult pests to manage. During the rice growing season (spring-summer), this pest remains inthe crop, causing annual losses of up to 65.2 kg/ha. Subsequently, during the post-harvestperiod (autumn-winter) this stink bug goes into diapause and takes refuge in the rice stubbleand in the native vegetation around the fields, which allows it to recolonize the crop in thefollowing season. Although its annual cycle in the agroecosystem is well established, it has notbeen studied in depth whether there are natural mechanisms that help control the populationsof this insect consistently throughout the year. Likewise, little is known about the naturalenemies in the overwintering refuges of this insect, which could contribute to the reduction ofits populations. Therefore, the aim of this study was to record the incidence ofentomopathogenic fungi affecting T. limbativentris in rice crops and surrounding vegetation.Seasonal sampling was carried out in different commercial rice fields in Argentina. Adultindividuals were collected during winter from the surrounding vegetation and during summerfrom rice plants. Collected individuals were transported to the laboratory and kept inquarantine. Mortality was recorded daily and the external development of mycelium on thecorpses was observed. As a result, three species of entomopathogenic fungi were identified:Metarhizium anisopliae s.l., Beauveria bassianas.l. and Purpureocilliumlilacinum (Ascomycota:Hypocreales), which naturally reduced the winter and summer populations by 33.08% and49.22%, respectively. These results reveal that entomopathogenic fungi could be goodcandidates for biological control of T. limbativentris in Argentine rice fields and raise thepossibility of exploring the potential of these fungal species to be used in seasonal pestmanagement programs in rice crops.