Nematicidal seed treatments are a relatively new strategy for managing plant-parasitic nematodes in row crops. Two such seed treatments, Avicta (abamectin) and Clariva (Pasteuria nishizawae), are marketed by Syngenta for use against Heterodera glycines in soybean production in the upper Midwest. The specific effects of these seed treatments on the biology of the nematode have not been previously reported. The effects of Avicta and Clariva on H. glycines hatching, movement, attraction, penetration, development, and reproduction were determined in controlled-environment experiments. Avicta inhibited juvenile movement and penetration at the seed depth and 3 cm below the seed. Clariva inhibited juvenile movement and penetration 3 and 5 cm below the seed and nematode development within the roots of young plants. Both seed treatments affected nematodes in 10- and 20-day-old plants, but effects were not detected on nematodes developing in older plants (30 and 60 days) with larger root systems. These results provide details of the specific mechanisms of early-season protection provided by Avicta and Clariva seed treatments.
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Chip Technologies for Screening Chemical and Biological Agents Against Plant-Parasitic Nematodes
Plant-parasitic nematodes cause substantial damage to agricultural crops worldwide. Long-term management of these pests requires novel strategies to reduce infection of host plants. Disruption of nematode chemotaxis to root systems has been proposed as a potential management approach, and novel assays are needed to test the chemotactic behavior of nematodes against a wide range of synthetic chemicals and root exudates. Two microfluidic chips were developed that measure the attraction or repulsion of nematodes to chemicals (“chemical chip”) and young plant roots (“root chip”). The chip designs allowed for chemical concentration gradients to be maintained up to 24 h, the nematodes to remain physically separate from the chemical reservoirs, and for images of nematode populations to be captured using either a microscope or a flatbed scanner. In the experiments using the chemical chips, seven ionic solutions were tested on second-stage juveniles (J2s) of Meloidogyne incognita and Heterodera glycines. Results were consistent with previous reports of repellency of M. incognita to a majority of the ionic solutions, including NH 4 NO 3 , KNO 3 , KCl, MgCl 2 , and CaCl 2 . H. glycines was found to be attracted to both NH 4 NO 3 and KNO 3 , which has not been reported previously. A software program was written to aid in monitoring the location of nematodes at regular time intervals using the root chip. In experiments with the root chip, H. glycines J2s were attracted to roots of 3-day-old, susceptible (cultivar Williams 82) soybean seedlings, and attraction of H. glycines to susceptible soybean was similar across the length of the root. Attraction to resistant (cultivar Jack) soybean seedlings relative to the water only control was inconsistent across runs, and H. glycines J2s were not preferentially attracted to the roots of resistant or susceptible cultivars when both were placed on opposite sides of the same root chip. The chips developed allow for direct tests of plant-parasitic nematode chemotaxis to chemicals and roots with minimal human intervention.
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- Award ID(s):
- 1556370
- NSF-PAR ID:
- 10334477
- Date Published:
- Journal Name:
- Phytopathology®
- Volume:
- 106
- Issue:
- 12
- ISSN:
- 0031-949X
- Page Range / eLocation ID:
- 1563 to 1571
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Two new in vitro methods were developed to analyze plant-parasitic nematode behavior, at the population and the individual organism levels, through time-lapse image analysis. The first method employed a high-resolution flatbed scanner to monitor the movement of a population of nematodes over a 24-h period at 25°C. The second method tracked multiple motion parameters of individual nematodes on a microscopic scale, using a high-speed camera. Changes in movement and motion of second-stage juveniles (J2) of the soybean cyst nematode Heterodera glycines Ichinohe were measured after exposure to a serial dilution of abamectin (0.1 to 100 μg/ml). Movement and motion of H. glycines were significantly reduced as the concentration of abamectin increased. The effective range of abamectin to inhibit movement and motion of H. glycines J2 was between 1.0 and 10 μg/ml. Proof-of-concept experiments for both methods produced one of the first in vitro sensitivity studies of H. glycines to abamectin. The two methods developed allow for higher-throughput analysis of nematode movement and motion and provide objective and data-rich measurements that are difficult to achieve from conventional microscopic laboratory methods.more » « less
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Summary Soybean cyst nematode (SCN;
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1094/PHYTO-06-16-0224-R
