Evaluation of Fungal Volatile Organic Compounds for Control the Plant Parasitic Nematode Meloidogyne incognita

Abstract

Plant parasitic nematodes are a serious threat to crop production worldwide and their control is extremely challenging. Fungal volatile organic compounds (VOCs) provide an ecofriendly alternative to synthetic nematicides, many of which have been withdrawn due to the risks they pose to humans and the environment. This study investigated the biocidal properties of two fungal VOCs, 1-Octen-3-ol and 3-Octanone, against the widespread root-knot nematode Meloidogyne incognita. Both VOCs proved to be highly toxic to the infective second-stage juveniles (J2) and inhibited hatching. Toxicity was dependent on the dose and period of exposure. The LD50 of 1-Octen-3-ol and 3-Octanone was 3.2 and 4.6 µL, respectively. The LT50 of 1-Octen-3-ol and 3-Octanone was 71.2 and 147.1 min, respectively. Both VOCs were highly toxic but 1-Octen-3-ol was more effective than 3-Octanone. Exposure of M. incognita egg-masses for 48 h at two doses (0.8 and 3.2 µL) of these VOCs showed that 1-Octen-3-ol had significantly greater nematicidal activity (100%) than 3-Octanone (14.7%) and the nematicide metham sodium (6.1%). High levels of reactive oxygen species detected in J2 exposed to 1-Octen-3-ol and 3-Octanone suggest oxidative stress was one factor contributing to mortality and needs to be investigated further.

Toxicity of fungal‐derived volatile organic compounds against root‐knot nematodes

“…For instance, 1‐octen‐3‐ol and 3‐octanone could lead to more than 80% mortality of RKNs, but the nematicidal activity depended on the concentration of compounds 12 . 1‐octen‐3‐ol had strongly ovicidal activity, which was regarded as potential soil fumigants 25 . In line with these studies, we found that 3‐methyl‐1‐butanol caused high mortality of J2s (~70%) during the VOCs fumigant bioassay, and also caused about 70% mortality during the direct contact bioassay, while the inhibitory effect did not increase with the concentration over 1 mg/L.…”

“…12 1-octen-3-ol had strongly ovicidal activity, which was regarded as potential soil fumigants. 25 In line with these studies, we found that 3-methyl-1-butanol caused high mortality of J2s (∼70%) during the VOCs fumigant bioassay, and also caused about 70% mortality during the direct contact bioassay, while the inhibitory effect did not increase with the concentration over 1 mg/L. Accordingly, 3-methyl-1-butanol might be a good candidate for RKNs control via multiple strategies, including inhibiting egg hatching, chemotaxis response, fumigant-and contact nematicidal activity.…”

“…15,22 Hummadi et al 23 reported that the Metarhizium brunneum VOCs reduced penetration efficacy of entomopathogenic nematodes in insect control. 23 The variation of suppression effects can be ascribed to differences in sensitivity of plant pathogens for microbial VOCs, 24,25 For example, 1-octen-3-ol (9.98% v/w) and 3-octanone (1 and 5% w/w), both produced by soil microbes, were able to kill an entire population of M. hapla in tomato plants. 12,26 Along these lines, a non-characterized blend of VOCs from Trichoderma sp.…”