By far the most threatening activity to most PDF's and many other flora and fauna is deforestation. Although there are plenty of laws in place to "protect" PDF's (and other flora and fauna) from collectors (CITES being one), there are not many things in place to protect their habitats from destruction. In a nutshell most countries that are home to PDF's are considered poor by our standards and the majority of the population has to make its living "off of the land". This usually means cutting down rainforest for crops and/or livestock. This is a very simplified view of one problem but hopefully it will give you some ideas on where to get started.