After playing in Wayfarer Foothills for ~30mins and killing quite a few different things I noticed that my daily Kill Variety Achievment was still at 0%.
I made a specific point to go kill different types of enemies, including skelk, ice wurms, dolyaks, freshwater crabs, tamini. However DKV remained at 0%.
I have played in both Wayfarrer Foothills and Genderran Fields as a lvl80 Asura Elementalist, not in a party. I have also confirmed these observations as a lvl11 Sylvari Mesmer in Caledon Forest against fireflies, mosquitoes, stags, and forest spiders. also not in a party.