Waitrose, which has stated that it wants to take 10% of the UK plant sales market, said:
"Our suppliers are always encouraged to take an Integrated Pest Management (IPM) approach to the control of insect pests. We have worked with our growers to ensure the effectiveness of IPM by a variety of measurements including Waitrose Farm Assessment and our collaborative industry leading training programmes."
Waitrose added: "The policy is agreed with our suppliers in a Code of Practice but this is commercially sensitive."
Meanwhile, the John Lewis Partnership has reported a 53% fall in half-year profits, despite sales growth at both its Waitrose supermarkets and department stores.
Profit before tax came in at £26.6m for the six months to 29 July.
Gross sales were up 2.3% for both brands - with revenue hitting almost £4.8bn, up 2.2% on the same period last year.
Operating profit before exceptional items and property profits was up 10% in John Lewis, but trading profits for Waitrose were 18% lower.
New products in Waitrose's essentials list include baby avocado, blueberries, sweet potatoes, tinned artichoke and olives.