Outbreaks of Dichroplus maculipennis and Bufonacris claraziana in Argentina: What do we know?

MARIOTTINI YANINA; DE WYSIECKI , MARIA LAURA; LANGE CARLOS ERNESTO

Merida

Congreso; International Congress of Orthopterology 2023; 2023

Since the beginning of agriculture and livestock farming in Argentina, some grasshopper species have been considered harmful to such activities. Over time and in different regions, significant outbreaks have been recorded. An increase in this problematic has been observed in recent decades, being the outbreaks of different species a recurrent phenomenon. The impact and magnitude of Dichroplus maculipennis in the South of the Pampas region (Between 2008 and 2021) and Bufonacris claraziana in diverse areas of Patagonia (Between 2016 and 2022) are worth mentioning. Dichroplus maculipennis is found in much of the country, and it is considered one of the most harmful grasshoppers, mainly in areas of the Pampas and Patagonia. Bufonacris claraziana is an endemic species of Argentinian Patagonia distributed from Neuquén to Santa Cruz provinces. With the aim of knowing the population dynamics of these species, we have carried out different studies about their ecology and biology. Field sampling (from 2005 to the present), as well as laboratory studies, have revealed the abundance, phenology, age structure, and sex ratio of D. maculipennis populations in grasslands and crops of the southern Pampas, and characteristics of its life cycle such as longevity, survival, fecundity, food consumption and preferences, and ecological efficiency, among others. Besides, studies on habitat preferences and the interaction between specific densities and climatic variables were performed. On the contrary, knowledge about population dynamics of B. claraziana is still very limited. From 2017 to the present, field sampling has been carried out in various localities of the Santa Cruz and Chubut provinces. In addition, some initial laboratory and field experiences have also been performed to evaluate the susceptibility of this species to the entomopathogenic Beauveria bassiana, a potential biocontrol agent. Even today some relevant characteristics of the biology and ecology of most Argentinian grasshopper pests remain largely unknown. We consider that sustained ecological studies over time are necessary to understand the dynamic relationships between intrinsic characteristics and environmental factors since they will facilitate forecasting and management of the pest species.