Combined application of entomopathogenic nematodes and fungi against fruit flies, Bactrocera zonata and B. dorsalis (Diptera: Tephritidae): laboratory cups to field study

Abstract

BACKGROUND: The peach fruit fly, Bactrocera zonata, and the Oriental fruit fly, B. dorsalis (Diptera: Tephritidae), are economically important fruit fly species in various regions of the world. We evaluated the effects of separate and combined applications of the entomopathogenic fungi (EPF) Beauveria bassiana (WG-18) and Metarhizium anisopliae (WG-02), and the entomopathogenic nematodes (EPNs) Heterorhabditis bacteriophora (VS strain) and Steinernema carpocapsae (ALL strain) against larvae, pupae and pharate adults, of B. zonata and B. dorsalis under laboratory, glasshouse and field cage conditions. RESULTS: Combined applications of EPF and EPNs produced greater mortality than individual treatments under all conditions. Against both species, the combination of B. bassiana and H. bacteriophora consistently exerted strong effects that were similar to the combined application of B. bassiana and S. carpocapsae whereas M. anisopliae applied with S. carpocapsae was least effective in all combinations. In a laboratory bioassay, synergistic interactions were detected between B. bassiana and H. bacteriophora applied against larvae and pharate adults of both fly species, between B. bassiana and S. carpocapsae against larvae of both species and pharate adults of B. zonata, and between M. anisopliae and H. bacteriophora against B. zonata larvae. Other combined treatments resulted in additive effects, especially against fly pupae. In a potted soil bioassay, there were only additive interactions in all combinations against different stages of both flies. The 3rd instar of both flies was more susceptible than pharate adult and pupal stages. Additive interactions between EPNs and EPF were detected in the glasshouse against 3rd instars and pupae, and under field conditions against 3rd instars of both fly species. CONCLUSION: These results indicate how particular combinations of entomopathogenic fungi and nematodes could be deployed in integrated pest management of tephritid fruit flies in orchard agro-ecosystems.

Interactions between Entomopathogenic Fungi and Entomopathogenic Nematodes

“…Another research work evaluated the effects of the combination of fungi and nematodes on fruit flies using Bactrocera zonata (Saunders) and B. dorsalis (Hendel) (Diptera: Tephritidae) by exposing the larvae, pupae, and pharate adults to B. bassiana s.s. and M. anisopliae s.s. in combination with H. bacteriophora and S. carpocapsae in laboratory, glasshouse, and field cage conditions [ 56 ]. Interestingly, all combined applications resulted in a greater mortality than individual treatments under all experimental conditions and, in general, B. bassiana s.s. was more effective in mixed treatments than M. anisopliae s.s.…”

“…In laboratory tests, many combinations resulted in a synergistic effect, while the interactions in the soil pots, glasshouse, and in the field were mostly additive. Based on the results, similarly to R. pomonella [ 56 ], fruit flies of the genus Bactrocera could be successfully targeted through the combination of entomopathogenic fungi and nematodes.…”

Review of entomopathogenic fungi and nematodes as biological control agents of tephritid fruit flies: current status and a future vision

“…Applications of EPFs [ M. anisopliae (WG‐02) and B. bassiana (WG‐18)] and EPNs [ H. bacteriophora (VS strain) and S. carpocapsae (ALL strain)] produced greater mortality of larvae, pupae, and pharate adults of B. zonata and B. dorsalis under laboratory, glasshouse, and field cages conditions, compared to individual treatments. The combination of B. bassiana and H. bacteriophora consistently exerted the strongest effects (Wakil et al, 2022).…”

Toxicity of Beauveria bassiana to Bactrocera dorsalis and effects on its natural predators

“…This fruit fly mainly lays eggs inside fruits and vegetables as an adult, and the larvae subsequently feed on the fruits and cause damage. It is precisely this concealed method of damage by fruit flies that makes their prevention and control challenging ( Wakil et al, 2022 ). To combat the harmful fruit fly, growers largely rely on chemical insecticides.…”