Many of the species have symbiotic relationships with ants, spiders, and other creatures. Clarke's book covers many aspects of this in detail. These plants are highly endangered, mostly because of habitat destruction from slash and burn agriculture. Populations are so small that collectors are having serious impact on the plants. This genus is one of the carnivorous plants most involved in illegal overseas trade.
Several species are extinct.
Probably the most threatened species is Nepenthes clipeata , and the International Carnivorous Plant Society is developing a recovery program to try and maintain this species, at least in cultivation. Sadly, this has produced a proprietary attitude among aficionados similar to the attitudes of some orchid enthusiasts. There are even cases of growers breaking into other growers' greenhouses to steal their plants. Worse yet, herbarium sheets of extinct specimens have been stolen. The genus Nepenthes is unique amongst the carnivorous plants as the only dioecious genus.