Insecticidal potency of a new bioactive dipeptide from <i>Bacillus velezensis</i> AR1 culture supernatant against <i>Myzus persicae</i>

Abstract

The green peach aphid (Myzus persicae) has become a worldwide challenge causing high yield losses through direct plant attack and transmission of plant pathogens. A widespread resistance development against synthetic agrochemicals by the aphid and the negative impact of the chemicals used to manage the pest on human health, other organisms and the environment are other problems. Therefore, the aphicidal potency of the secondary metabolite from Bacillus velezensis AR1 was investigated under in-vitro conditions. The purification process was conducted using solid-phase extraction by Strata SI-1 column, thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Then, the purified EA3T3 fraction was analysed with the nuclear magnetic resonance (NMR ¹H, ¹³C, H-H COSY, HSQC, and HMBC) and the metabolite was identified as 5-N-tyrosinylornithine. The aphicidal potency of the metabolite on Myzus persicae mortality was tested using three concentrations over 24 to 72h periods of exposure in a laboratory bioassay in comparison with a biopesticide E-II. The biopesticide EII caused the highest mortality of the aphids; 89% at 72 hr. The purified metabolite caused a mortality rate of 40.74±6 to 66.67±5% at 1 to 4μg mL^-1 concentrations after 72h of exposure. The aphid mortality increased with the increase in concentration and duration of exposure to EA3T3. The lowest LD₅₀ was attained at 72h of exposure. Therefore, the bioactive metabolite produced by B. velezensis AR1 is potent against the green peach aphid Myzus persica and has the potential to be used for the management of aphids.