Feeding preference of Diabrotica speciosa (Ger.) (Coleoptera: Chrysomelidae) by broccoli leaves from natural, organic and conventional farming systems

Abstract

Multiple-choice laboratory tests were achieved to compare feeding preference of Diabrotica speciosa (Ger.) to leaves of broccoli (Brassica oleraceae L. var. italica) from natural, conventional and organic farming systems. Natural farming systems included incorporation of the elephant grass Pennisetum purpureum Schumacher cv. Napier (50 ton/ha), Bokashi compost (1.5 ton/ha) and spray of EM 4 (Natural 1), or the incorporation of the Bokashi compost (1.5 ton /ha) and spray of EM 4 (Natural 2), and in the conventional, NPK + borax were incorporated in the planting + dressing N and organic compost (1 kg/ plant) was incorporated in the organic system. Organic compost was prepared using crop residues of corn (Zea mays L.), soybean [Glycine max (L.) Mer.], and cattle manure. Leaf discs were collected and placed in cages in multiple-choice tests. Beetles preferred mostly broccoli leaves from conventional farming system than leaves from Natural (1 and 2) and Organic farming systems. Feeding on leaves from Natural 1, Natural 2 and Organic farming system were 68, 67 and 57% of the feeding on leaves from Conventional farming system.