The collapse in British butterfly populations is a “warning from nature” about the resilience of the UK’s ecosystems, says England’s nature chief, raising concerns about threats to national food security as the planet continues to heat.

Tony Juniper, the chair of Natural England, says new data showing a sharp fall in butterfly populations this summer was probably the consequence of habitat loss and the use of pesticides, making the insects less resilient to extreme weather fluctuations: the scorching heat and wetter weather driven by global heating.

Figures from Butterfly Conservation this week showed observed butterfly numbers had almost halved to 935,000 – the lowest ever total in the 14-year history of the UK count. Species including the common blue, the small tortoiseshell and Scotch argus recorded their lowest ever figures, according to the data.