TL;DR
Data suggest that combining silicon-induced resistance with T. pretiosum biological control offers an effective and durable approach to controlling fall armyworm while improving maize performance.
Infestation by the invasive fall armyworm-FAW (Spodoptera frugiperda) pest has recently emerged as an important constraint for maize (Zea mays L) production, which is frequently managed using chemical pesticides. However, the inappropriate use of chemical pesticides can cause deleterious effects on the environment and humans, and enhance pest resistance. This study evaluated the potential of locally produced microbial inoculants and plant bioactive extracts, and push-pull strategy of cowpea (Vigna unguiculata) intercropping as control measures for FAW infestation on maize plants, while serving as nutrient replenishing source via biological nitrogen fixation. This field study was setup as split plot in two alternate cropping seasons (September 2021 and April 2022) and cropping systems (mono- and inter-cropping) as main plots, and seven treatments as sub-plots (Control, chemical–NPK+Lamida gold, Tithonia diversifolia–Ti+Piper guineense–Pi, Plant growth-promoting bacteria–PGPB+Endophytic fungi–EF, EF+Pi and PGPB+EF+Ti+Pi). Results highlight statistical identical performance of microbial inoculants or plant bioactive extracts and chemical pesticides in reducing FAW infestation by 13-73.9 %. Bio-amendments significantly (P<0.05) increased maize height, 1000 maize grain weight, cob length and degree of filling compared to the untreated control. Maize-cowpea intercrop significantly increased FAW infestation in some treatments when compared to maize monocrop. In September 2021, FAW infestation correlated (P<0.05) negatively with 1000 maize grain weight (r = -0.7), cob length (r = -0.7), number of grains on the longest line (r = -0.8) and degree of filling (r = -0.7) in the monocrop plot. These findings highlight the ability of locally produced microbial inoculants and plant bioactive extracts as sustainable alternatives to mitigate FAW infestation on maize. Thereby, opening up possibilities for further investigation on mechanisms of action that can be explored for biological pest control.
Fall armyworm, Spodoptera frugiperda, is a major maize pest requiring effective and environmentally sustainable management strategies. This study evaluated the efficacy of Beauveria bassiana, Metarhizium anisopliae, pheromone traps, and their integration under field conditions in Iraq. Significant differences (P ≤ 0.05) were observed among treatments for larval density, plant infestation, and damage severity. The untreated control recorded the highest larval density (3.46 larvae plant-1), infestation (52.4%), and damage severity (2.86). In contrast, the combined application of B. bassiana + pheromone traps provided the greatest suppression, reducing larval density to 0.92 larvae plant-1 (73.4% reduction), infestation to 18.7% (64.3% reduction), and damage severity to 1.21 (57.7% reduction) relative to the control. Among individual treatments, B. bassiana was more effective than M. anisopliae, reducing larval density to 1.35 larvae plant-1, infestation to 24.5%, and damage severity to 1.48. Pheromone traps alone provided moderate suppression, with corresponding values of 2.14 larvae plant-1, 33.6%, and 1.94, respectively. The superior performance of the combined treatment was attributed to simultaneous suppression of larvae by fungal infection and adult males through pheromone trapping, although synergistic interaction was not statistically established. Overall, integrating entomopathogenic fungi with pheromone-based control showed strong potential for reducing S. frugiperda populations and maize damage while supporting sustainable integrated pest management under field conditions.
The inverse relationship between larval weight and development duration highlights the role of maize genotype in influencing FAW growth dynamics, with resistant varieties prolonging development and suppressing larval biomass accumulation.
ABSTRACT Diatomaceous earth (DE) and entomopathogenic fungi (EPF) are promising residue-free alternatives to synthetic insecticides for stored-product protection. This study evaluated the individual and combined additive effects of a local Turkish DE formulation, Diaterra®, and two indigenous EPF isolates, Beauveria bassiana and Metarhizium anisopliae, against Sitophilus oryzae adults on stored wheat. Treatments included DE at 100, 200, and 400 ppm, fungal suspensions at 1 × 10⁶, 1 × 10⁷, and 1 × 108 conidia mL−1, and their binary combinations. Adult mortality was assessed at 7, 14, and 21 days after treatment, while F₁ progeny production was evaluated after 56 days. DE alone showed a clear dose-dependent effect, with 100 ppm causing 72.87% mortality at day 21, whereas 200 and 400 ppm achieved ≥97.43% mortality within 7 days and complete mortality by days 14–21. EPF sprays alone produced moderate mortality (<48%). Binary mixtures accelerated mortality, particularly at higher DE rates; combinations of 400 ppm DE with fungal isolates caused 87.09–95.01% mortality at day 7 and 98.66–100% mortality by days 14–21. Immersion bioassays confirmed higher direct virulence of B. bassiana than M. anisopliae, reaching 92.49% and 36.59% mortality at day 7 and 97.92% and 77.09% at day 21, respectively. Reproductive suppression was strongest with DE treatments, with 200 and 400 ppm reducing F₁ emergence by 97.8% and 99.4%, respectively. Binary mixtures improved progeny suppression mainly at the lowest DE rate. Overall, Diaterra® provided rapid adult mortality and strong reproductive suppression, while DE–EPF combinations showed additive benefits under stored-wheat conditions.
The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a devastating pest of maize, and host plant resistance offers a sustainable alternative to chemical control. This study evaluated the resistance of the maize germplasm CH1 against FAW through life table parameters, feeding and oviposition preferences and greenhouse experiment. Results showed that FAW larvae reared on CH1 exhibited significantly prolonged larval development (21.61 d vs. 12.49 d), reduced survival (65.00% vs. 94.00%), and lower fecundity (689.00 vs. 1369.93 eggs per female) compared to those on the susceptible control Huang C. Population parameters, including the intrinsic rate of increase (r) and net reproductive rate (R0), were significantly lower on CH1. Behavioral assays revealed strong feeding and oviposition preferences for Huang C over CH1. Greenhouse experiment confirmed that CH1 plants sustained only minor damage (Davis scale grade 2, resistant), whereas Huang C plants were severely damaged (grade 7, susceptible). These findings demonstrate that CH1 possesses multi-dimensional resistance against FAW, providing a promising genetic resource for breeding FAW-resistant maize varieties and supporting sustainable pest management strategies.
