The relevance of taxonomy in agroecological studies on pests. The case of Oebalus species in Neotropical rice fields

DELLAPÉ, GIMENA; FRANCESCHINI, CELESTE; GERVAZONI, PAULA; FUENTES, DANIELA; CUBILLA, MARÍA

Jinzhou

Congreso; The 7th International Conference on Agricultural and Biological Sciences (ABS 2021); 2021

Bohai University

The study of the seasonal bioecology of pest species is a fundamental issue for the development of integrated pest management schemes in subtropical and temperate rice paddies. In the case of stink bugs (Hemiptera: Pentatomidae), there are reports of several pest species that show seasonal dimorphism as a consequence of the activation/inactivation of the diapause during the nymphal stage, processes regulated by the photoperiod at certain times of the year. These events generate phenotypic changes that have not been deeply studied for some groups, which causes confusion at the agronomic level because these phenotypes are erroneously considered as different species. This is the case of the Oebalus Stål species complex, which show great phenotypic variability in neotropical rice fields. The objective of this work was to analyze the polymorphism and seasonal abundance of Oebalus species present in rice (Oryza sativa L.) in Argentina. Sampling was carried out during the crop cycle, in early and late sown plots, from November to April (spring to autumn). Adult stink bugs were collected using different techniques (manually in 250cc bottles and with entomological nets). The collected material was preserved in 96% ethanol and identified following the appropriate bibliography. As a result, 2091 adult individuals of two species of Oebalus were collected, with the highest abundance in O. poecilus with 83.79% of the total number of individuals collected. Five different morphotypes were detected in this species, while two different morphotypes were collected for O. ypsilongriseus. Significant differences in abundance between morphotypes were recorded for each species, with morphotype 1 standing out for O. poecilus and the typical morphotype of the species for O. ypsilongriseus. The months of the highest abundance of both Oebalus species were March and April, months in which the highest abundance of atypical morphotypes was also recorded. The results presented here contribute to the correct identification and monitoring of these pest species in Neotropical rice fields, emphasizing the great seasonal phenotypic plasticity of O. poecilus in these paddies. Likewise, the results obtained highlight the importance of including specialists in taxonomy in agroecological studies of pests to avoid mistakes in the interpretation of data obtained in the field and to be able to carry out more precise ecological analyses at the species level.