Management of potato cyst nematodes with special focus on biological control and trap cropping strategies.

Potato cyst nematodes (PCNs; Globodera spp.) are one of the most difficult pests of potato to manage worldwide. Indiscriminate use of pesticides and their hazardous effects discourage the use of many chemicals for the management of PCNs. As a result, biological control agents and trap crops have received more attention from growers as safer ways to manage PCNs. The biological control agents such as Pochonia chlamydosporia, Purpureocillium lilacinum, Trichoderma spp., Pseudomonas fluorescens, Bacillus spp., Pasteuria spp., and others are recognized as potential candidates for the management of PCNs. Moreover recently, the use of trap crop Solanum sisymbriifolium also showed promise by drastically reducing soil populations of PCNs. Integration of these management strategies along with other practices including identification, conservation, and multiplication of native antagonists, will facilitate efficient management of the PCNs in potato cropping system. Some of the promising research approaches that are being used against PCNs are addressed in this review. © 2022 Society of Chemical Industry.

Biocontrol potential of entomopathogenic nematodes for the sustainable management of Spodoptera frugiperda (Lepidoptera: Noctuidae) in maize.

BACKGROUND: The occurrence of Spodoptera frugiperda (J.E. Smith) in Asia was reported for the first time from Karnataka in 2018. This pest is widely distributed in India, causing significant damage to maize. Management of this recent invasive pest in maize-growing regions of India relies on chemical control. Resistance is the greatest obstacle to the successful use of chemical insecticides to control this pest. Indiscriminate use of chemical insecticides destroys beneficial natural enemies, therefore effective and sustainable alternative control strategies are needed. In this case, the use of biological control agents is the alternative option to mitigate this pest. Thus, this study aimed to select virulent entomopathogenic nematodes (EPNs) isolates based on the laboratory assay and further to test the efficacy of virulent isolates in the field conditions along with commonly used chemical insecticide emamectin benzoate against S. frugiperda. RESULTS: Laboratory results revealed that both Heterorhabditis indica 1 NBAIIH38 and Steinernema carpocapsae NBAIRS59 caused 100% mortality in third- and fourth-instar larvae of S. frugiperda, while these two species caused 85% and 72% mortality in pupae, respectively. When pupae of S. frugiperda were exposed to EPNs, pupae died after metamorphosis to malformed adults. All the nematode species were able to penetrate and reproduce within S. frugiperda larvae, but the reproduction rate for Heterorhabditids was higher than that of Steinernematids. Field trial results showed that H. indica 1 NBAIIH38 significantly reduced the number of larvae and leaf damage scores compared to S. carpocapsae NBAIRS59. Emamectin benzoate was more effective in reducing the larval population compared to EPN species. The cob yield was significantly higher in EPN- and emamectin benzoate-treated plots than in untreated control plots. CONCLUSION: Overall, these experiments suggest H. indica 1 NBAIIH38 is a promising biocontrol agent against S. frugiperda in maize production. © 2022 Society of Chemical Industry.

Efficacy of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) on developmental stages of house fly, Musca domestica.

The housefly, Musca domestica is a major domestic, medical and veterinary pest. The management of these flies reliance on insecticide, causes environmental constraints, insecticide resistance and residues in the meat, skin. Therefore one of the eco-friendly alternate methods is by using biological agents such as entomopathogenic nematodes (EPN). In the present study evaluated the survival of EPN species Steinernema feltiae, Heterorhabditis indica, S. carpocapsae, S. glaseri and S. abbasi in poultry manure and also their efficacy against different developmental stages of house fly. After exposing to poultry manure, S. feltiae showed more survival as followed by H. indica, S. carpocapsae, S. glaseri and S. abbasi in all exposition period. When the exposition period extended to 96 h, all nematode species survivability was drastically reduced. After exposing these nematodes to poultry manure at 24 h their virulence capacity against wax moth, Galleria mellonella showed all the nematode species were able cause 100% mortality. However their progeny production was significantly reduced. Fly eggs and pupae were refractory to these nematode infection. Petri dish without artificial diet assay showed that, second and 3rd-instar larvae were highly susceptible to EPNs as compared to larvae provided with artificial diet. H. indica showed high virulence capacity compared to other nematodes tested. Poultry manure assay revealed that, H. indica and S. carpocapsae caused minimal mortality where as S. feltiae, S. glaseri and S. abbasi did not cause any mortality. This may be because of poor survival and limited movement of nematodes in poultry manure which may be due to ammonia, other toxic substances in poultry manure. The decrease in larval mortality in manure suggests that biocontrol of housefly by using EPNs is unlikely.