How many species worldwide are resistant to 22 out of the 25 known herbicide sites of action?

The assertion that more than 200 species worldwide are resistant to 22 out of the 25 known herbicide sites of action is supported by extensive research in the field of herbicide resistance. As herbicides have been used increasingly in agriculture, a number of plant species have developed mechanisms to survive treatment by these chemicals. This resistance has emerged across various species and crops, emphasizing the effectiveness of certain herbicides but also revealing a significant challenge for crop management.

The figure of over 200 resistant species indicates how widespread and serious herbicide resistance has become globally. This has notable implications for weed management strategies, as these resistant species can negatively affect crop yields and require the use of alternative management practices. Understanding the number and diversity of resistant species is critical for developing integrated pest management strategies to minimize resistance development.

In contrast, the other potential answers would underestimate the scale of the issue. Less than 200 or about 100 would not accurately reflect the current findings in herbicide resistance research, overlooking the comprehensive nature of resistance mechanisms that have occurred across many species globally.