Application of Entomopathogenic Nematodes to Control Larvae of Temnorhynchus baal (Reiche and Saulcy) Under Laboratory Conditions and In Strawberry Fields

Abstract

The white grub, Temnorhynchus baal, is a major pest of the strawberry crop in many Asian and African countries. The white grabs cause significant economic losses in the yield. The present study aims to evaluate the effectiveness of entomopathogenic nematodes (EPNs) on the third larval instar of T. baal under laboratory conditions. The study extended to compare the efficacy of a combination of EPNs (Steinernema glaseri+Heterorhabditis bacteriophora) against a natural infestation of T. baal with an organophosphorus insecticide (Diazinon) in an Egyptian strawberry field. In the laboratory, five larvae of T. baal were placed in soil and infected with EPNs. At the highest concentration of 4000 IJs/larva, the larvae were more susceptible to infection with S. glaseri than H. bacteriophora, with mortality percentages of 96 and 88%, respectively. The LC50 of S. glaseri and H. bacteriophora was 937.44 and 1026.58 IJs/larvae, respectively. The mortality percentage was 96% and 100% when treated for five larvae/cup and one larva/cup, respectively, after being infected with a combination of S. glaseri+ H. bacteriophora. The mortality percentage was higher in the mixture than for each species studied individually. In the field, throughout the seasons, the percentage of wilted plants was 17.64, 66.09, and 83.95% in 2020 and 12.56, 67.87, and 75.62% in 2021, for the plots treated with a combination of EPNs, insecticides, and control, respectively. Present findings indicate that entomopathogenic nematodes are good alternatives to control the white grub, T. baal, in strawberry fields.

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

“…In a study conducted by Peçen and Kepenekci (2022) on adults of wheat stink bug Aelia rostrata (Hemiptera: Pentatomidae), S. carpocapsae (Black sea isolate) was the most pathogenic among three EPNs tested including S. feltiae and H. bacteriophora isolates. Also, larvae of T. baal were more susceptible to the infection with S. glaseri than H. bacteriophora, at the highest concentration (4000 IJs/larva) (Adly et al, 2022). In the study of Nouh (2022), S. glaseri showed the highest efficacy against the 2 nd and 3 rd instar larvae of P. bispinosus compared to H. bacteriophora and S. carpocapsae.…”

“…Based on their data, LD50 of H. bacteriophora was 13.054 IJs/termite, and LD50 of S. aciari was 42.040 IJs/termite. Then, Adly et al (2022) treated the larvae of T. baal with S. glaseri and H. bacteriophora and estimated LC50 values as 937.44 and 1026.58 IJs/larvae, respectively. According to Sujithra et al (2022), LC50values of S. carpocapsae Sc1, S. abbasi Sa1 and H. indica Hi1 strains were 1078, 1663 and 9780 IJs larva −1 , respectively, at 72 h of incubation of O. rhinoceros larvae.…”