Biology and predation potential of the hemipteran predator, Rhynocoris marginatus (Fab., 1794) on the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

Abstract

Abstract Background The notorious invasive pest fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), native to Americas entered the Asian continent and was first time reported on maize from India in 2018. The predatory species Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) has been reported as a potential predator that preys on a number of economic pests in India such as Helicoverpa armigera (Hubner), Spodoptera litura (Fabricius), Mythimna separata (Walker), and Anomis flava (Fabricius). The present study described the biology and feeding potential of the predator on S. frugiperda under laboratory conditions where temperature and relative humidity varied from 26 to 28 °C and 75–80%, respectively, and the photoperiod was L12: D12 hrs. Results Incubation period and the total nymphal/developmental period of the predator were 9.65 and 55.89 days, respectively. The percentage of survivorship of nymphs to adults was 62.50%. Females showed a higher longevity than males. The predator’s fecundity reached 349.30 eggs/female, laid in 6 to 8 batches. Abdominal length and width were greater in the case of females than in males. Male consumed about 158.55 larvae of the fifth instar prey, at an average of 1.86 larvae per day. Females consumed a greater number of larvae (184.95) than males, with a higher daily predation rate of 1.93 larvae. Time taken to approach the prey was longer in the case of males (5.58 min) than females (3.57 min), whereas handling time was longer in females (115.37 min) than in males (85.71 min). Weight gained by females (61.90 mg) was higher than that by males (44.20 mg) after 24 h of predation. Conclusions The present study revealed that female adult predator and fifth-instar nymphs of R. marginatus preyed efficiently on S. frugiperda. The shorter ovipositional period of the predator was a positive sign for its mass multiplication, enabling rapid buildup of the predator population. This study is a step in the evaluation of the efficacy of R. marginatus feeding on fall armyworm. Further field studies are required on its mass release and effect in reducing the fall armyworm larval population.

Keywords

• Rhynocoris marginatus
• Spodoptera frugiperda
• Predation potential
• Biological parameters
• Handling time
• Approach time