Re-emergence of Dichroplus maculipennis (Blanchard) (Orthoptera: Acrididae: Melanoplinae) as a pest in the Pampas region of Argentina.

MARIOTTINI YANINA; DE WYSIECKI MARIA LAURA

Kunming

Congreso; 11 th International congress of Orthopterology; 2013

The main objective of this study was to determine the status of D. maculipennis in representative plant communities of the southern Pampas region (Laprida county) for eight consecutive seasons (2005-06 to 2012-13). The collecting sites were classified into four categories: native grasslands? (extensive coverage of native grasses), halophilous grasslands (extensive coverage of Distichlis spicata), implanted pastures (mostly Agropyron), and disturbed grasslands (grazed native grasses with significant coverage of introduced weeds like Cardus pycnocephalus and Centaurea calcitrapa). Three replicates of each category were established, which were constant throughout the study. Dichroplus maculipennis density varied significantly in all plant communities (p<0.0001). The lowest densities [0.10 ± 0.04 ind/m2 (0-1.7 ind/m2)] were recorded in the first season. Afterwards, there was a progressive and significant increase until the 2009-10 season (p <0.0001) when the highest density values were recorded [27.8 ± 3.1 ind/m2 (2.8 -56.3 ind/m2) on average]. Subsequently, in the next three sampling periods, a decrease in density was registered. While in season 2010-11 the density was still high [15.6 ± 0.9 ind/m2 (0-26.11 ind/m2) on average], it was significantly lower than in the previous season (p <0.0001). In the last two seasons average densities were lower (8.23 ​​± 0.53 ind/m2 in 2011-12; 3.56 ± 0.25 ind/m2 in 2012-13), but significantly higher than in the first one. There were no significant differences between densities of the four plant communities in each season (p>0.05).