Biochemical effects of Steinernema feltiae, Steinernema riobrave and Heterorhabditis bacteriophora on Spodoptera littoralis larvae

Abstract

In the present study, the infectivity of the three entomopathegnic nematodes, Steinernema feltiae, Steinernema riobrave and Heterorhabditis bacteriophora, on the cotton leafworm, Spodoptera littoralis was studied. Moreover, the effect of these pathogens on certain biochemical and physiological aspects of the host was also studied. H. bacteriophora, appeared to be more pathogenic than S. riobrave and S. feltiae to the S. littoralis larvae. The highest production (7000 infective juveniles) was obtained, where infective juvenile production from cadavers infected with H. bacteriophora was higher than that produced from cadavers infected with S. riobrave and S. feltiae. The principle nutrients (total protein, carbohydrate and lipid) of the host larvae were highly decreased post-infection with the nematodes S. riobrave and H. bacteriophora. The activity of some larval enzymes was also affected due to infection by these nematodes. Thus, the activity of carbohydrate hydrolyzing enzymes (amylase, invertase and trehalose) changed depending on the species of the pathogen and the enzyme. Amylase activity decreased with the infection by H. bacteriophora, and the reverse was obtained with the infection by S. riobrave and S. feltiae where such activity increased. Invertase and Trehalase activity increased with the infection by three nematode species. The highest increase was obtained in case of infection by S. riobrave. Activities of acid and alkaline phosphatases increased due to infection by S. riobrave, H. bacteriophora. The only exception was a non-significant decrease in the alkaline phosphatase activities of larvae infected with S. feltiae. Whereas, the activity of transaminases (GOT and GPT) was highly decreased with the infection by H. bacteriophora and S. riobrave.

Virulence of Entomopathogenic Nematodes and their Symbiotic Bacteria against Insect Pests, with Special Reference to Agrotis ipsilon (Lepidoptera: Noctuidae): A Comprehensive Review.

“…riobrave and H. bacteriophora. In their study on S. littoralis, Ahmed,et al (2014) found an increasing mortality percentage of larvae with the increase in concentrations of S. feltiae, S. riobrave and H. bacteriophora. Some years later, Shaurubet al (2021) assessed the effects of some EPN strains onC.…”

“…For example, Hussaini et al (2005) found that the isolates of H. indica were more virulent than the isolate of S. carpocapsae against the A. ipsilon larvae. Some years later, H. bacteriophora was more pathogenic than S. riobrave and S. feltiae to S. littoralis larvae (Ahmed et al, 2014). Some strains of H. bacteriophora were found more virulent than S. carpocapsae strains against late 3 rd instar larvae of C. capitata (Shaurub et al, 2015).…”

“…Apart from A. ipsilon, LC50 values for H. bacteriophora, S. riobrave and S. feltiae against S. littoralis larvae were 5.01, 8.57 and 16 IJs/larva, respectively (Ahmed et al, 2014). Also, Gomaa et al (2020) investigated the pathogenicity of H. bacteriophora and S. carpocapsae against 3 rd instar larvae of S. littoralis.…”

Control of Culex pipiens (Diptera: Culicidae), the vector of lymphatic filariasis, using irradiated and non-irradiated entomopathogenic nematode, Steinernema scapterisci (Rhabditida: Steinernematidae)

“…Since El-Sadawy et al (2009) demonstrated a significant decline in total protein and total lipids and alteration in different amino acids concentration in both Parasarcophaga sarchophaga and Argas persicus post treatment with H. bacteriophara and S. riobrave. Furthermore, Ahmed et al (2014) declared a significant decrease in the principle nutrients (total protein, carbohydrate, and lipid) and the activity of transaminases (GOT and GPT) of Spodoptera littoralis after treatment with H. bacteriophora and S. riobrave.…”