Endophytic Colonization by Beauveria bassiana and Metarhizium anisopliae in Maize Plants Affects the Fitness of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The fall armyworm, Spodoptera frugiperda (Noctuidae; Lepidoptera), is a serious threat to food security as it has the potential to feed on over 353 plant species. To control this insect pest, endophytic colonization of entomopathogenic fungi (EPF) in plants is being considered as a safer and more effective alternative. This study evaluated the efficacy of two EPFs, Beauveria bassiana and Metarhizium anisopliae, for endophytic colonization using foliar spray and seed treatment methods on maize plants, and their impact on the survival, development, and fecundity of S. frugiperda. Both EPF effectively colonized the maize plants with foliar spray and seed treatment methods, resulting in 72-80% and 50-60% colonization rates, respectively, 14 days after inoculation. The EPF negatively impacted the development and fecundity of S. frugiperda. Larvae feeding on EPF-inoculated leaves had slower development (21.21 d for M. anisopliae and 20.64 d for B. bassiana) than the control treatment (20.27 d). The fecundity rate was also significantly reduced to 260.0-290.1 eggs/female with both EPF applications compared with the control treatment (435.6 eggs/female). Age-stage-specific parameters showed lower fecundity, life expectancy, and survival of S. frugiperda when they fed on both EPF-inoculated leaves compared with untreated leaves. Furthermore, both EPFs had a significant effect on population parameters such as intrinsic (r = 0.127 d-1 for B. bassiana, and r = 0.125 d-1 for M. anisopliae) and finite rate (λ = 1.135 d-1 for B. bassiana, and λ = 1.1333 d-1 for M. anisopliae) of S. frugiperda compared with the control (r = 0.133 d-1 and λ = 1.146 d-1). These findings suggest that EPF can be effectively used for the endophytic colonization of maize plants to control S. frugiperda. Therefore, these EPFs should be integrated into pest management programs for this pest.

Biotic Potential Induced by Different Host Plants in the Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae).

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a polyphagous insect pest of many important crops. To evaluate the influence of host plants on the biology and survival of the Pakistani population of S. frugiperda, we examined life table parameters of S. frugiperda raised on maize, sorghum, wheat, and rice. The development rate was significantly higher on the maize crop than on the other three host plants. Different larval diets affected development time and fecundity. S. frugiperda attained the fastest larval development (16 days) on maize and the slowest development (32.74 days) on rice. Adult females from maize-fed larvae laid 1088 eggs/female, those from sorghum-fed larvae laid 591.6 eggs/female, those from wheat-fed larvae laid 435.6 eggs/female, and those from rice-fed larvae laid 49.6 eggs/female. Age stage-specific parameters also indicated the higher fecundity, higher life expectancy, and higher survival of S. frugiperda on maize plants than on the other three hosts. Larval diets had a significant varying effect on the finite and intrinsic increase rates, reflecting that maize was the most suitable diet. The findings of the present study are useful for predicting population dynamics especially in areas cultivating Poaceae crops, except maize, to develop sustainable integrated pest management strategies for this pest.

Effects of Entomopathogenic Fungi on the Biology of Spodoptera litura (Lepidoptera: Noctuidae) and its Reduviid Predator, Rhynocoris marginatus (Heteroptera: Reduviidae).

Entomopathogenic fungi (EPFs), Isaria fumosorosea and Beauveria bassiana, are efficient biological agents in the management of multiple arthropod pests. In this study, the effects of both EPF species on various life stages of Spodoptera litura (F.) (Lepidoptera: Noctuidae) and its natural enemy Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) were determined under laboratory conditions. I. fumosorosea significantly (P < .05) reduced the growth rate of the third and fourth instar larvae of S. litura. For relative consumption rate (RCR), the maximum impact was recorded for I. fumosorosea, which reduced the RCR of the larvae. The larvae of S. litura treated with I. fumosorosea showed significantly lower efficiency of conversion of ingested food (ECI) and the larval mortality rate (58.0%) was also higher compared with B. bassiana (33.3%). Similarly, I. fumosorosea had a significant effect on the pupal formation of S. litura; however, no significant effect was found on adult emergence percentage. To determine the effect of EPF-infected prey on the adult predator, their handling time, predatory rate, consumption rate, and the survival rate were recorded. No significant effect of EPF species on the predation rate was found. Furthermore, no significant difference was found in the survival rate of predators fed on either EPF-infected prey or healthy larvae. The interaction of these EPFs with a reduviid predator suggested that both EPF species, especially I. fumosorosea, could be used together with the predator to boost the biological control of S. litura in commercial crops.