Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 26, 2009
Publication Date: July 26, 2010
Citation: Masler, E.P., Zasada, I.A., Sardanelli, S., Rogers, S.T., Halbrendt, J.M. 2010. Effects of benzyl isothiocyanate on the reproduction of Meloidogyne incognita on Glycine max and Capsicum annuum. Nematology. 12(5):693-699. Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. Because several chemical pesticides used to control nematodes have been withdrawn from use, growers possess a critical need for the discovery of environmentally and economically sound nematode control agents. One approach to discovering new ways to control nematodes is to identify ways to inhibit their infectivity and reproduction using naturally derived compounds. We have previously shown that compounds called isothiocyanates (ITCs) released by some plants when they decompose in soils are toxic to certain species of nematodes. In this report, we briefly exposed the root-knot nematode, the most economically damaging nematode species worldwide, to low levels of ITCs and examined their ability to infect soybean and pepper plants. The results indicated that low ITC levels suppressed infection of root-knot nematodes on pepper and soybean and significantly decreased nematode reproduction on these two species. The discovery is significant because it identifies a natural nematicide of high potency, effective with multiple crops. Consequently, this information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective methods for nematode control.
Technical Abstract: Reproduction of Meloidogyne incognita on Capsicum annuum or Glycine max was suppressed when infective juveniles (J2) were exposed to 0.03 millimolar benzyl isothiocyanate (BITC) for 2hr prior to inoculation of the host. Infectivity assessed by gall index was significantly reduced on both G. max (control index, 3.75; BITC index, 1.28) and C. annuum (control index, 3.42; BITC index, 1.23). In C. annuum, 14% of plants inoculated with BITC-treated J2 produced egg masses compared with 93% in controls, and egg mass score was reduced (control score, 2.75; BITC index, 1.07). Egg production was reduced in C. annuum by 24% and by a remarkable 97% in G. max. Two measures of plant health, root weight and shoot weight, were reduced in C. annuum (control root, 2.16 g; BITC root, 1.22g; control shoot, 2.04g; BITC shoot, 1.05g), but not in G. max, when plants were inoculated with treated J2. However, plant health was not correlated with egg production on either host plant and regardless of treatment. There were very strong interactions between egg production, as measured by mean total eggs/plant (G. max) or mean total eggs/egg mass (C. annuum), and hatching of J2 from eggs obtained from all combinations of plant host and J2 treatment. J2 hatch from eggs obtained from G. max was significantly lower when plants had been inoculated with BITC-treated J2 (8.62% hatch at 14 days after egg collection) than when plants had been inoculated with control J2 (33.52%). Such effects were not observed with C. annuum. BITC may have important residual consequences on the progeny of M. incognita not directly exposed to the chemical.