Can the botanical azadirachtin replace phased-out soil insecticides in suppressing the soil insect pest Diabrotica virgifera virgifera?

Abstract Background Due to recent bans on the use of several soil insecticides and insecticidal seed coatings, soil-dwelling insect pests are increasingly difficult manage. One example is western corn rootworm ( Diabrotica virgifera , Coleoptera: Chrysomelidae), a serious root-feeder maize Zea mays ). We investigated whether less problematic botanical azadirachtin, widely used against above-ground insects, could become an option for control this pest. Methods Artificial diet-based bioassays were implemented under standard laboratory conditions establish dose response curves pest larvae. Then, potted-plant experiments in greenhouse assess feasibility efficacy novel granular formulation azadirachtin more natural relation insecticides. Results Bioassays three repetitions revealed 3-day LD 50 22.3 µg azadirachtin/ml which corresponded 0.45 µg/neonate D. v. 5-day 19.3 µg/ml or 0.39 µg/first second instar larva. No sublethal effects observed. The that currently proposed 38 g azadirachtin/hectare in-furrow application at sowing not enough prevent root damage. At 10× standard-dose total was achieved as well prevention most This better than by cypermethrin-based granules comparable tefluthrin-granules, thiamethoxam coatings. ED suppressing larval populations estimated 92 azadirachtin/ha, preventing heavy damage 52 g/ha general 220 g/ha. Conclusions There seems clear potential development neem-based arable crops such maize. They might become, if doses increased phased out, promising, safer solution part integrated management toolkit insects.