The Impact of Cu Ion, Two Novel Schiff Base Ligands and their Copper (II) Complexes on the Biological Activity of the Entomopathogenic Nematodes

Abstract

Background. Many biotic and abiotic soil components affect entomopathogenic nematode (EPN's) activity, infectivity, host finding ability and the rate of reproduction. Since, copper being an essential element, could be toxic at its elevated concentrations in soils, the study was aimed therefore to evaluate the biological effect of Cu ion and safer alternatives, i.e. Schiff base ligands and their copper complexes on EPN's juveniles. Methods. Two novel Schiff base ligands of 2-amino 3-cyano 1, 5 diphenylpyrrole and salicylaldehyde (HL 1) or 2-hydroxy11-naphthylaldehyde (HL 2) and their copper (II) complexes were synthesized and characterized. Their effect on the infectivity and reproduction potential of the Egyptian entomopathogenic nematodes (EPN's) Heterorhabditis bacteriophora and the imported Steinernema carpocapsae were tested at 1.5 mg/l and 11.0 mg/l. Results. The infectivity of Cu (II) ion treated H. bacteriophora and S. carpocapsae juveniles (at low and high concentrations) generally reduced, (33.30 % and 11.50%) and (88% and 75%) respectively, as compared with that of control. The infectivity of the ligands and complexes treated H. bacteriophora and S. carpocapsae juveniles at both concentrations matches that of the non-treated nematodes (100%). The reproduction of H. bacteriophora and S. carpocapsae decreased with increasing concentrations of copper (II), the ligands (HL 1 , HL 2) and complexes (C1, C2) except in HL 1 for H. bacteriophora and C2 for S. carpocapsae. The difference in reproduction potentials of the tested EPN's due to the dose variations of the agents was observed to be insignificant. Conclusions. Although the pollution of soil with copper (II) ions affects nematode infectivity and reproduction potential, Schiff base ligands and their copper complexes were found to be less harmful and hence the latter could be used in combination with fertilizers to overcome one of the abiotic factors enhancing the field efficacy of EPN.

Efficacy of Egyptian Parasitic Nematodes, Heterorhabditis bacteriophora (BA1) and Steinernema carpocapsae (BA2) in Bio-control of Economically Important Pests

“…The mortality variability caused by various species and strains of EPNs against various insect pests is well known. Our data are in line with previous studies suggesting that nematodes are generally highly effective against Noctuids and Pyrilds larvae (Lepidoptera: Noctuidae and Pyrilidae) at low levels of IJs (Bedding et al 1983;Glazer and Navon, 1990;Glazer et al 1991;West and Vrain, 1997;Feaster and Steinkrauss, 1999;El-Wakeil, and Hussein;Metwally et al 2012;Nouh and Hussein, 2014;Yuksel and Canhilal, 2018;Hussein et al 2018 ;Amutha et al 2020). The recorded results are also in agreement with previous bioassays suggesting that EPNs are effective against Curculionidae larvae (Saleh et al, 2009;Williams et al, 2015).…”

Heterorhabditis brevicaudis: A New Nematode Species Isolated from El-Dakhla Oasis in Egypt and Its Efficiency against Some Lepidopteran Pests

“…However, most of these isolates remain unidentified at the species level. The need for more effective EPNs for controlling insect pests have stimulated efforts on EPNs surveys worldwide (Hussein et al, 2018;Webster et al, 2002). This has resulted in the recovery of many new species of EPNs.…”