Identification and Mapping of Cross-Resistance Patterns to ALS-Inhibitors in Greater Beggarticks (Bidens spp.)

Abstract

Greater beggarticks (Bidens pilosa and Bidens subalternans) biotypes have been under selection pressure of ALS-inhibitors since early 90’s in Brazil. The objectives of this work were to investigate whether there are different cross-resistance patterns among ALS-inhibitors herbicides in Bidens spp. biotypes; to understand the geographic distribution of resistance patterns in grains producing regions in Brazil; and evaluate the possibility of multiple resistance to ALS-inhibitors, EPSPs inhibitor and photosystem II inhibitors. Dose-response experiments were carried out with imazethapyr, chlorimuron and diclosulam in three populations. Sensibility to others 34 populations both from Paraná State (PR) and from others Brazilian regions were also evaluated. The dose-response assay revealed cross-resistance with different patterns. One population was resistant to all three herbicides, the second population was tolerant to both imazethapyr and chlorimuron, but not to diclosulam, while a third population was resistant merely to imazethapyr. The results exhibited different cross-resistance patterns, since they can be found in other Bidens spp. populations. However, no relationship was observed between geographic areas where samples were collected and resistance patterns. Conclusively, the most frequent resistance pattern was R2 (resistance to imazethapyr, chlorimuron and diclosulam).

Multiple resistance to glyphosate and imazethapyr in Bidens subalternans

“…In both years, survival levels were ≥62% for R, and the calculated dose of imazethapyr to provide ≤10% survival exceeded the highest dose applied (>848 g ai ha -1 ). The results found here are similar to the RF range found for ALS inhibitors in other B. subalternans populations from South America (Lamego et al, 2009;Mendes et al, 2019).…”

“…Means followed by the same letters indicates no difference by Tukey's test (P<0.05); 1/ dose in g ea; 2/ applied with non-ionic surfactant at 0,2% v v -1 ; 3/ applied with mineral oil at 0,5% v v -1 ; DAT: days after treatment. in this class, consistent with what has been described in other greater beggarticks populations across South America (Lamego et al, 2009;Mendes et al, 2019). For HPPD-inhibiting herbicides (mesotrione and tembotrione), frequently used in corn fields, their tank mix with atrazine can provide efficient greater beggarticks control (Matte et al, 2018).…”

“…Over the last three growing seasons, growers have reported greater beggarticks (Bidens subalternans) survival after glyphosate treatment in soybean and corn areas in Paraguay. Considering that extensive soybean and corn fields areas are infested with greater beggarticks resistant to ALS inhibitors (Mendes et al, 2019), it is possible that some populations have been selected for multiple resistance (glyphosate and ALS inhibitors) in these areas. Therefore, our objective was to investigate multiple resistance to EPSPs-and ALS-inhibitors in a putative resistant greater beggarticks population from Paraguay, and evaluate alternative herbicides to chemical control for that population.…”