Compatibility of chemical insecticides and entomopathogenic fungi for control of soybean defoliating pest, Rachiplusia nu

Abstract

Rachiplusia nu (Guenée) (Lepidoptera: Noctuidae) is one of the major lepidopteran pests defoliating soybeans (Glycine max Merrill) in Argentina. The combined use of chemical insecticides and entomopathogenic fungi is a promising pest-control option to minimize adverse chemical effects. In this work, we evaluated the interactions between five insecticides-two being considered biorational-and five fungal entomopathogenic strains under laboratory conditions in order to determine the possible usefulness of combinations of these agents against R. nu. The insecticides were tested for compatibility at four doses by in vitro bioassay and for the lethality of R. nu by inoculations at three doses. Fungal strains were applied at 1×10, 1×10, and 1×10conidia/ml. The combinations of those insecticides with Beauveria bassiana (LPSc 1067, LPSc 1082, LPSc 1098), Metarhizium anisopliae (LPSc 907), and Metarhizium robertsii (LPSc 963) caused higher R. nu-larval mortalities than any of the individual agents alone. We observed significant differences in the in vitro conidial viability, vegetative growth, and conidia production of the five strains of entomopathogenic fungi exposed to different doses of the chemical insecticides. The combination gamma-cyhalothrin-LPSc-1067 caused the highest percent mortality of R. nu larvae, with synergism occurring between the two agents at 50% and 25% of the maximum field doses.

Interactions of fungal entomopathogens with synthetic insecticides for the control of Kuschelorhynchusmacadamiae (Coleoptera: Curculionidae)

“…In a similar study, Pelizza et al. (2018) reported that whilst insecticides (e.g., gamma‐cyhalothrin, lambda‐cyhalothrin, rynaxypyr, luphenuron, methoxyfenozide) and EPF at their FFCs effectively controlled the moth Rachiplusia nu Guenée, the combination of the control agents did not provide any further benefits. The synergistic interactions between insecticides and EPF could be detected only when both control agents were reduced to 50% of their FFCs or lower (Pelizza et al., 2018).…”

“…(2018) reported that whilst insecticides (e.g., gamma‐cyhalothrin, lambda‐cyhalothrin, rynaxypyr, luphenuron, methoxyfenozide) and EPF at their FFCs effectively controlled the moth Rachiplusia nu Guenée, the combination of the control agents did not provide any further benefits. The synergistic interactions between insecticides and EPF could be detected only when both control agents were reduced to 50% of their FFCs or lower (Pelizza et al., 2018). Morales‐Rodriguez and Peck (2009) also found that synergistic interactions were only apparent when imidacloprid was reduced from half to one‐quarter of its FFC when combined with B. bassiana for controlling the white grub Popillia japonica Newman.…”

The Fungus Metarhizium sp. BCC 4849 Is an Effective and Safe Mycoinsecticide for the Management of Spider Mites and Other Insect Pests

“…Application of M. anisopliae in combination with one µg imidacloprid/g resulted in mortality of 88% of Cyrtomenus bergi nymphs compared to 40% for the fungal application alone. In a study of interactions between five synthetic insecticides and five fungal strains, a combination of insecticides with B. bassiana and M. robertsii caused higher Rachiplusia nu mortalities than any individual agents alone [37]. In our study, we used a combination of an entomopathogenic fungus with a diluted dose of synthetic acaricide.…”

Compatibility of Entomopathogenic Fungi, Beauvaria bassiana (Bals. -Criv.) Vuill. and Metarhizium anisopliae (Metchn) Sorokin Isolates with Different Agrochemicals Commonly Used in Vineyards.

“…Fiedler and Sosnowska (2017) mentioned that the imidacloprid (Confidor 200 SL) had low toxicity to the B. bassiana fungus. Gamma and lambda-cyhalothrin had the lowest adverse effect on conidial germination of the different isolates of B. bassiana and M. anisopliae, while Significant differences were obtained in the vegetative growth of different fungal isolates (Pelizzaa et al, 2018).…”