Assessments of iodoindoles and abamectin as inducers of methuosis in pinewood nematode, Bursaphelenchus xylophilus

Abstract

Bursaphelenchus xylophilus is a quarantined migratory endoparasite known to cause severe economic losses in pine forest ecosystems. The study presents the nematicidal effects of halogenated indoles on B. xylophilus and their action mechanisms. 5-Iodoindole and abamectin (positive control) at low concentration (10 µg/mL) presented similar and high nematicidal activities against B. xylophilus. 5-Iodoindole diminished fecundity, reproductive activities, embryonic and juvenile lethality and locomotor behaviors. Molecular interactions of ligands with invertebrate-specific glutamate gated chloride channel receptor reinforced the notion that 5-iodoindole, like abamectin, rigidly binds to the active sites of the receptor. 5-Iodoindole also induced diverse phenotypic deformities in nematodes including abnormal organ disruption/shrinkage and increased vacuolization. These findings suggest the prospective role of vacuoles in nematode death by methuosis. Importantly, 5-iodoindole was nontoxic to two plants, Brassica oleracea and Raphanus raphanistrum. Henceforth, the study warrants the application of iodoindoles in ecological environments to control the devastating pine destruction by B. xylophilus.

Activity profiling of barley vacuolar processing enzymes provides new insights into the plant and cyst nematode interaction

“…The most visible feature in cells undergoing methuosis is the accumulation of fluid-filled cytoplasmic vacuoles derived from macropinosomes (Maltese and Overmeyer, 2014). Similar formation of vacuoles in nematode bodies was recently described for Meloidogyne incognita exposed to oxalic acid (Jang et al, 2016) and in Bursaphelenchus xylophilus incubated in 5-iodoindole (Rajasekharan et al, 2017). In both cases, morphological variations in the internal organs of treated nematodes and formation of vacuoles/granules and large voids within nematode bodies occurred, which are similar to the morphological alterations in H. filipjevi pre-parasitic juveniles treated with kalata B1.…”

Screening, isolation and evaluation of a nematicidal compound from actinomycetes against the pine wood nematode, Bursaphelenchus xylophilus

“…Hatching is one of the most important parameters affecting population numbers, and any chemical with high hatching inhibition can be considered a potential nematicide. 45 In the present study, spectinabilin and abamectin both effectively reduced the hatching of B. xylophilus eggs (Fig. 7), thereby fulfilling the decisive criteria of a prospective nematicide.…”

“…(C), (D) and (E)), which support that spectinabilin effectively controls the reproductive traits of B. xylophilus . Hatching is one of the most important parameters affecting population numbers, and any chemical with high hatching inhibition can be considered a potential nematicide . In the present study, spectinabilin and abamectin both effectively reduced the hatching of B. xylophilus eggs (Fig.…”

“…The presence of vacuoles was previously reported in Meloidogyne incognita, known to cause root-knot disease in plants, 46 and B. xylophilus treated with iodoindoles. 45 Those reports described severe morphological variations in M. incognita following treatment with oxalic acid, which showed complete destruction of internal organs, 46 and the death of B. xylophilus caused by 5-iodoindole was thought to be attributed to the increased vacuolisation by methuosis, as some of these compounds can destroy the nematode's physical barrier or tissues. 47 We observed similar morphological changes in the B. xylophilus treated with spectinabilin.…”

Hydropic anthelmintics against parasitic nematodes

“…ATP, adenosine triphosphate. The phenotypes were re-constructed by adopting images and concepts from our previous publications [12,14].…”