Entomopathogenic nematodes as biological control agent against Bactrocera zontat and Bactrocera dorsalis (Diptera: Tehpritidae)

Authors: USMAN, MUHAMMAD - University Of Agriculture - Pakistan; WAKIL, WAQAS - University Of Agriculture - Pakistan; SUFYAN, MUHAMMAD - University Of Agriculture - Pakistan; Shapiro Ilan, David

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2021
Publication Date: 7/7/2021
Citation: Usman, M., Wakil, W., Sufyan, M., Shapiro Ilan, D.I. 2021. Entomopathogenic nematodes as biological control agent against Bactrocera zontat and Bactrocera dorsalis (Diptera: Tehpritidae). Biological Control. https://doi.org/10.1016/j.biocontrol.2021.104706.
DOI: https://doi.org/10.1016/j.biocontrol.2021.104706

Interpretive Summary: Fruit flies are key pests of many crops. The insects attack fruit directly. However, a part of the insect’s life-cycle, particularly the pupal stage, occurs in the soil. To control the insect, broad spectrum chemical insecticides are sprayed. Due to regulatory and environmental concerns, research to develop alternative measures to control the pest is warranted. Entomopathogenic nematodes (also known as beneficial nematodes) are potential alternatives to chemical insecticides for control of apple maggot. Nematodes are round worms. Unlike harmful plant parasitic nematodes, entomopathogenic nematodes only attack insects and thus they are used as environmentally-friendly biopesticides to control a wide variety of economically important insect pests. The objective of our research was to determine if entomopathogenic nematodes can kill two species of fruit flies named Bactrocera zonata and Bactrocera dorsalis, and to assess which nematode species is the most virulent. Laboratory, greenhouse and field experiments were conducted. We tested ten different nematode species and found a nematode named Heterorhabditis bacteriophora is the most promising for control of the targeted fruit fly species. This research opens up new avenues to explore for developing safe alternative pest management approaches.

Technical Abstract: We evaluated ten different species of entomopathogenic nematodes (EPNs) Heterorhabditis bacteriophora, H. megidis, H. georgiana, H. floridensis, H. indica, Steinernema carpocapsae, S. riobrave, S. feltiae, S. rarum and S. glaseri against different developmental stages i.e. larvae, pupae and adult of Bactrocera zonata and Bactrocera dorsalis. In a Petri plate all the EPN species caused infection with the lowest survival levels observed in H. bacteriophora treatments against B. zonata and B. dorsalis. In a potted soil bioassay, both developmental stages were found susceptible to the different EPN species, but again H. bacteriophora caused the highest levels of mortality: 95.74% and 86.88% in larvae and 71.27% and 67.65% in pupae of B. zonata and B. dorsalis, respectively. In a fruit exposure bioassay under laboratory condition, all EPN species were lethal towards larvae even inside the fruit and also in soil with maximum mortalities caused by H. bacteriophora in both fly species. Under greenhouse conditions, the lowest adult emergences (ranging from 19% to 52%) were observed in H. bacteriophora treatments when EPNs were exposed as larvae and pupae of B. zonata and B. dorsalis. Under field conditions, the same EPN species were tested and all the species significantly reduced adult fly emergence, but the lowest adult emergence was observed when using H. bacteriophora (25.06% and 31.53% in B. zonata and B. dorsalis, respectively). In the field, EPNs performed better in artificially infested fruit with mortalities of 47.18% and 42.03% as compared to natural infested fruit with mortalities of 36.88% and 30.86% in B. zonata and B. dorsalis, respectively. Our results indicate that EPNs could be part of an integrated pest management program for control of soil inhabiting stages of fruit fly complexes in orchard systems of Pakistan.