Abstract
Background The invasive peach fruit fly (PFF), Bactrocera zonata (Saunders) (Diptera: Tephritidae), is a native of South
east Asia. Entomopathogens like nematodes, bacteria, viruses and fungi have been shown to be effective as a biologi
cal control agent against B. zonata. Evaluation the efficacy of different entomopathogenic nematode isolates (EPNs)
belonged to the two families (Steinernematidae and Heterorhabditidae); (Steinernema carpocapsae (AII), S. carpocap
sae (EGAZ10), Heterorhabditis bacteriophora (HP88) and H. indica (EGAZ2) was carried out against the full‑grown larvae
of B. zonata under laboratory, semi‑field and field conditions.
Results Data revealed that in all the tested nematode isolates succeeded to reduce the emerging of the PFF, B.
zonata compared to controls with significant differences. The LC50 values were 794.3, 1063.2, 1249.8 and 1446.8 IJs/ml,
for S. carpocapsae (AII), S. carpocapsae (EGAZ10), H. bacteriophora (HP88) and H. indica (EGAZ2), respectively, at 3 days
post treatments. The strain, S. carpocapsae (AII) was effective than S. carpocapsae (EGAZ10). Also, the strain H. bacterio
phora (HP88) was more effective than H. indica (EGAZ2). Therefore, the combination between the effective two stein
ernematid strains (S. carpocapsae (AII) & S. carpocapsae (EGAZ10)) and the two heterorhabditis strains (H. bacteriophora
(HP88) & H. indica (EGAZ2)) was efficient in the semi‑field experiment. In field condition, the combination of the two
efficient strains S. carpocapsae (AII) and H. bacteriophora (HP88) at the concentration of 3000 IJs/ml was more effective
in controlling B. zonata causing mortality 97.5%. The Co‑Toxicity factor values were − 67.6 for the combination of S.
carpocapsae (AII) with S. carpocapsae (EGAZ10) which recorded an antagonistic effect. Also, antagonistic effects were
observed for the combined application of H. bacteriophora (HP88) with H. indica (EGAZ2) (− 66.6) in semi‑field applica
tion; and the same effect was recorded for the combination of S. carpocapsae (AII) with H. bacteriophora (HP88) (− 42.6)
in field application.
Conclusion All EPNs’ experiments showed that the efficacy of foreign nematodes than the local ones. So, combina
tion of the two highly effective imported strains gave satisfied results, especially in the field experiment. |
