Biocontrol potential of native entomopathogenic nematodes against Gonioctena fornicata (Brüggemann, 1873) (Coleoptera, Chrysomelidae) in alfalfa

Abstract

Abstract Background Gonioctena fornicata (Brüggemann, 1873) (Coleoptera: Chrysomelidae) inflicts substantial crop damage by consuming alfalfa leaves. The main aim of the study was to develop an efficient, sustainable control method against the pest, considering entomopathogenic nematodes (EPNs) as a potential control agent against soil-dwelling insect pests. This study investigated the impact of two native entomopathogenic nematodes (EPNs), Heterorhabditis bacteriophora (isolate Z-1) and Steinernema feltiae (isolate A-16), on mature larvae and adults of G. fornicata. Concentrations of 250, 500, and 1000 IJs/ml were used for adult and larval stages, and mortality rate was determined at the end of 144 h for larvae and 240 h for adults. Results The highest effect was 94.7% at 120 h for isolate Z-1 and 91.0% at 168 h for isolate A-16 at a concentration of 1000 IJs/ml for adult stages. The highest effect on larval stage was 97.6% at 96 h for isolate Z-1 and 85.8% at 120 h for isolate A-16 at the concentration of 1000 IJs/ml. On the adult stage, isolate Z-1 showed 50.0–67.1% effect at concentrations of 250 and 500 IJs/ml, respectively, while isolate A-16 showed an effect ranging from 46.7 to 63.6%. In the larval stage, isolate Z-1 caused 39.7–77.6% mortality at 250 and 500 IJs/ml concentrations, respectively, while the rate was 32.9–63.9% for isolate A-16. In the trial, isolate Z-1 showed a high efficacy in both stages of G. fornicata. Conclusions This study represents the first laboratory investigation encompassing both adult and mature larval stages of G. fornicata. The obtained data offer valuable insights for alternative control strategies targeting G. fornicata.