Compatibility of indigenous isolates HR1, HR2 of entomopathogenic nematodes, with low-toxicity insecticides for control of fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Invasive species are a major danger to agronomic and natural ecosystems, and due to environmental concerns about pesticide use, EPNs have the potential to replace larvicidal action in pest management. The goal was to see how well local isolates of Steinernema feltiae (HR1) and Heterorhabditis bacteriophora (HR2) controlled invasive species when combined with low-toxicity pesticides. HR1 + Spinosad, chlorantraniliprole produced over 90% mortality in larvae at 96 hours, while HR2 + Spinosad, chlorantraniliprole caused over 95% mortality at 96 hours. After treatment, the high dose was regarded the least hazardous technique for controlling fall armyworm. At the high dose, HR1 + Spinosad, chlorantraniliprole produced larvae death of over 100 percent at 96 hours, and HR2 + Spinosad, chlorantraniliprole caused mortality of over 97.50 percent at 96 hours, and should be considered as a least hazardous strategy for T. absoluta management. Controlling larvae mortality of above 100% at 96 hours in combination with low-toxicity insecticide dosages should be included as a least harmful technique to control T. absoluta. The results showed that these HR2 strains have high pathogenicity against T. absoluta and S. frugiperda and have potential for control in integrated approaches, causing 100 percent and 90.00 percent mortality of T. absoluta and S. frugiperda at 96 hours at the high dose as a least toxic strategy to control.

Entomopathogenic Nematodes for the Management of Plum Curculio in Highbush Blueberry

Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae) is a key pest of stone and pome fruits in the United States. Application of certain entomopathogenic nematode (EPN) species has shown efficacy in some crops when targeting the larval stage of C. nenuphar in soil. To date, however, no EPNs have been tested for the control of this pest in highbush blueberries. In 2020, laboratory and field studies were conducted to: (1) determine the persistence of Steinernema riobrave, S. carpocapsae, S. feltiae, and Heterorhabditis bacteriophora in acidic blueberry soil; (2) compare the virulence of these EPNs to C. nenuphar larvae and pupae; and (3) compare the efficacy of these EPN species to control this pest in blueberry fields. The greatest persistence in blueberry soil was exhibited by S. riobrave followed by S. carpocapsae. Superior virulence was observed in S. riobrave against C. nenuphar larvae and pupae. Promising levels of virulence were also observed in S. carpocapsae and S. feltiae against the larvae, but S. scarabaei had low virulence. In the field, S. riobrave provided significantly higher levels of C. nenuphar suppression (90%) than the other EPNs. The field efficacy of S. riobrave against C. nenuphar at low and high rates was confirmed in 2021. Steinernema riobrave has the potential to become an important component in the management of C. nenuphar in highbush blueberry.

Steinernema Feltiae- Xenorhabdus Bovienii: More Information about this Bactohelminthic Complex from Iran

Background: Entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae that are symbiotically associated with Xenorhabdus and Photorhabdus bacteria are one of the effective biological control agents of insect pests. Native isolates can probably be more efficacious to control insect pests than exotic ones due to their adaptability to indigenous environmental conditions. Results: In this study, Steinernema feltiae isolate FUM221 was recovered from soil samples collected from the Fandoghloo pasture, Ardabil province, Iran. Morphological investigations of the first and second-generation adults, infective juveniles, and molecular characterizations were given based on ITS and 18S rDNA genes. Besides, molecular analysis based on the 16S rRNA region and phenetic data recognized Xenorhabdus bovienii as its symbiont bacterium. The scanning electron microscopy (SEM) images verified the identification of this isolate.Conclusion: The molecular characterization using two loci and phylogenetic analyses provided more evidence for the classification of this steinernematid and its difference of the same species from other countries. Moreover, molecular and phenetic characterizations of its symbiotic bacterium were provided with low variations compared to other isolates. Herein, the comprehensive taxonomic data of this steinernematid from Iran is presented.