Susceptibility of Myzus persicae, Brevicoryne brassicae and Nasonovia ribisnigri to Fungal Biopesticides in Laboratory and Field Experiments

Improved control of Rhopalosiphum maidis and Acyrthosiphon pisum, using the predatory natural enemy Harmonia axyridis carrying entomopathogenic fungi

BACKGROUND

Aphids are important agricultural and forestry pests that not only directly harm plants, but also transmit various plant viruses. Biological control, including the use of entomopathogenic fungi (EPFs) and predatory natural enemies, can effectively control aphids. However, there are few reports on the combined use of natural enemies carrying EPF to enhance the efficiency of aphid control.

RESULTS

In the present study, we evaluated the compatibility of five EPF strains with adults of the Harlequin ladybird (Harmonia axyridis). The pathogenicity, impact on predatory function, and fertility of EPF on H. axyridis were assessed as indicators, and the control efficiency of the predator carrying EPF was evaluated. The results showed that four EPF strains did not exhibit direct or indirect pathogenicity toward H. axyridis. Additionally, they did not significantly affect the survival rate, predation function, egg production or hatching rate of adult H. axyridis. The feeding rate of H. axyridis on Acyrthosiphon pisum was significantly lower than that of the control group after 0 h of starvation, but there were no significant differences observed following 24 and 48 h of starvation. Under semi-field conditions, the release of H. axyridis that had been treated previously with Metarhizium rileyi resulted in a significantly higher control of A. pisum and Rhopalosiphum maidis on Day 4 with aphid mortality rates of 83.33% and 98.35%, respectively. In comparison, the H. axyridis treatment group exhibited 46.22% and 84.16% mortality, respectively, whereas the M. rileyi treatment group experienced 10.67% and 61.06%, respectively.

CONCLUSION

Four EPF isolates showed no effect on the survival and predation of adult H. axyridis. The M. rileyi treatment had no effect on the reproduction of H. axyridis, yet H. axyridis adults carrying EPF conidia had a significantly higher control efficiency toward two species of aphids compared to each type of enemy alone. Therefore, predator dissemination of EPF may be an efficient and low-cost strategy for controlling of aphids. © 2025 Society of Chemical Industry.

Emulsifiable oil-formulated Beauveria bassiana competes with imidacloprid for seasonal control of cereal aphids in Zhejiang, China

BACKGROUND

Alternatives to neonicotinoids against cereal aphids are needed to mitigate aphid resistance and non-target effects. The emulsifiable oil formulations of two Beauveria bassiana strains, namely Bb registered as a mycoinsecticide and TBb overexpressing an endogenous virulence factor, were tested for seasonal control of cereal aphids at the elongating (April 7) to milk ripening (May 12) stages of winter wheat crop in Yuhang, Zhejiang. Each of three field trials consisted of blank control and the treatments (three randomized 100-m2 plots per capita) of each fungal strain sprayed biweekly at rates of 1.0 × 1013 and 1.5 × 1013 conidia ha-1 and 10% imidacloprid WP sprayed biweekly at a label rate.

RESULTS

Tiller infestation percentage and aphid density in the 5-week field trials after the first spray were reduced to 18.7-22.4% and 9.1-12.4 aphids per tiller in the fungal treatments, and 12.8-25.3% and 2.8-20.9 aphids per tiller in the chemical treatment, contrasting with 49.2-60.3% and 37.1-108.5 aphids per tiller in the control. Percent control efficacies (±SD) computed with weekly aphid densities over the period averaged 84.0 ± 1.6 and 85.3 ± 1.8 versus 78.0 ± 4.0 and 79.9 ± 3.2 in the high-rate versus low-rate treatments of Bb and TBb, respectively, and 84.5 ± 7.8 in the chemical treatment. Imidacloprid showed faster kill action but more variable efficacy than the fungal treatments throughout the trials.

CONCLUSION

Either Bb or TBb formulation competes with imidacloprid in reducing percent infestation and aphid density. The overall efficacy was significantly higher in the treatments of TBb than of Bb. © 2024 Society of Chemical Industry.

Direct and Indirect Effect via Endophytism of Entomopathogenic Fungi on the Fitness of Myzus persicae and Its Ability to Spread PLRV on Tobacco

Simple Summary

Aphids are major crop pests that are feeding on plant sap and transmitting plant viruses, thus inducing high yield losses worldwide. As chemical pesticides are decreasingly used in plant protection, fungi that cause disease to insects (entomopathogenic fungi) are one of the promising alternatives. They are commonly applied by spraying plants to protect them against herbivores. When applied, some fungi penetrate and live within plant tissues, thus helping to internally protect from insect attacks and other plant diseases. The aim of our study was to assess the effects of entomopathogenic fungi (EPF) applied firstly by contact after insect direct spraying, secondly by endophytic plant inoculation, and thirdly by associated both methods assessing the green peach aphid performances. The impact of the presence of endophytic entomopathogenic fungi (EEPF) in plant tissues on virus transmission by aphids was also considered. We found that the EPF Beauveria bassiana killed the green peach aphid and reduced its fecundity regardless of the application method. On fungal-inoculated plants, there was also a high mortality of aphid nymphs and infection by the potato leafroll virus (PLRV) was delayed by about a week with the EEPF treatment compared to fungal-free plants. This study showed that spraying plant leaves with EPF not only has a direct insecticidal effect against insects but could also have beneficial side effects for the plant against viruses.

Abstract

Aphids are major crop pests that transmit more than half of all insect-vectored plant viruses responsible for high yield losses worldwide. Entomopathogenic fungi (EPF) are biological control agents mainly used by foliar application to control herbivores, including sap-sucking pests such as aphids. Their ability to colonize plant tissues and to interact with diverse plant pathogenic microorganisms have been reported. In our study, we evaluated the effectiveness of Beauveria bassiana ((Balsamo-Crivelli) Vuillemin) directly applied by contact or/and indirectly via endophytism in tobacco plants (Nicotiana tabacum L.) against the virus vector Myzus persicae (Sulzer) carrying the Potato leafroll virus (PLRV) or not. We found that both contact treatment and endophytic colonization of leaves significantly increased aphid mortality and decreased the fecundity rate when compared to control plants. In addition, on fungal-colonized leaves, viruliferous aphids were more negatively impacted than virus-free ones and nymph mortality was significantly higher than on fungal-free plants. Furthermore, we assessed PLRV transmission by M. persicae on tobacco plants inoculated with either B. bassiana or Metarhizium acridum ((Driver and Milner) JF Bischoff, Rehner, and Humber) as source or/and recipient plants. Myzus persicae was found to acquire and transmit PLRV regardless of the treatment. Nevertheless, the infection rate of endophytically colonized plants was lower at a seven-day incubation period and had increased to almost 100% after fifteen days. These results suggest that B. bassiana is effective against aphids, both by contact and via endophytism, and both B. bassiana and M. acridum delayed PLRV infection in tobacco.