NEMATODES AND SOIL HEALTH IN TROPICAL AND SUBTROPICAL AGROECOSYSTEMS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1017228
• Project Start Date: Oct 1, 2018
• Project End Date: Sep 30, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822

Performing Department
Plant & Environmental Protection Sciences

Non Technical Summary
Nematodes are a diverse group of animals occupying multiple levels in the soil food web. Some nematodes feed on plants, whereas others feed on animals, including nematodes. Within the nematode community, plant-parasitic nematodes represent "bad" players. Plant-parasitic nematodes infect and feed on plants both above ground and below ground. Plant-parasitic nematodes adversely affect plant growth, plant yield, as well as the quality of the plant products. In Hawaii's tropical and subtropical ecosystems, Rotylenchulus reniformis, the reniform nematode, Meloidogyne sp., the root-knot nematodes, and Radopholus similis, the burrowing nematode, are major plant-parasitic nematodes affecting production of crops such as pineapple, papaya and other fruit crops, vegetables crops, coffee, and foliage and flower crops. Other plant-parasitic nematodes can be serious problems on other crops. Consequently, it is imperative to manage plant-parasitic nematodes for sustainable agricultural production. The nematode community is also composed of "good" players. Desirable nematodes include fungal, bacterial, and algal feeding nematodes because they are integral in nutrient cycling in the soil. Agricultural management practices that enhance and increase the population densities of these nematodes, such as reduced tillage operations and cover crops should be encouraged. Another group of desirable nematodes are the entomopathogenic nematodes (EPN). EPN are insect-parasitic nematodes and infect kill insect pests. EPN have been successfully deployed as biological control agents against a wide range of insect pests. The use of EPN, through augmented releases or creation of favorable environments, is beneficial to sustainable agricultural production. This project will investigate and develop tactics for nematode community management that increase soil health through laboratory, greenhouse and field tests. Field days and extension workshops will be held and scholarly publications produced for local, national, and international audiences. Students will be trained during the course of the project.

Animal Health Component

80%

Research Effort Categories

Basic

10%

Applied

80%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
212	1020	1120	25%
212	1099	1120	25%
216	1020	1120	25%
216	1099	1120	25%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
1020 - Pineapple; 1099 - Tropical/subtropical fruit, general/other;

Field Of Science
1120 - Nematology;

Keywords

plant-parasitic nematode

entomopathogenic nematode

nematode management

tropical crops

soil health

Goals / Objectives
The sustainable production of food and fiber requires attention to the nematode community. Production practices for both plants and animals can be adapted to enhance good nematodes and suppress bad nematodes. The goal of this project is to investigate and develop tactics for nematode community management that increase soil health. The specific objectives are to:1) Integrate management tactics for plant-parasitic nematodes to improve soil health;2) Investigate biological aspects of plant-parasitic and entomopathogenic nematodes to exploit for soil health management; and3) Disseminate information on soil health management.

Project Methods
Integrate management tactics for plant-parasitic nematodes to improve soil health: This objective will focus on evaluating cover crops, host-plant resistance (such as in alternative cover crops like mint), and new chemical products (such as fluopyram and fluensulfone) for soil health management. Cultures of reniform, root-knot and burrowing nematodes will be maintained in the laboratory and greenhouse. Burrowing nematode will be maintained on anthurium in the greenhouse and in sterile carrot disk cultures in the laboratory. Reniform nematodes will be maintained in the greenhouse on cowpea, pineapple and papaya plants. Cultures of the root-knot nematodes M. javanica, M. incognita, and M. konaensis will be maintained on tomato or coffee. For greenhouse experiments of nematode resistance or hostplant status, plants will be established from seeds, cuttings, or other propagules and planted into pot filled with a sterile sand:soil mixture. Pots will be arranged in random complete blocks. Each treatment or cultivar will be replicated at least four times, and the entire experiment will be repeated at least once. Plants will be inoculated with size appropriate numbers of the desired nematodes. Depending on the experimental objective, the plants will be grown from 1 to 9 months. At termination, plants will be removed from pots and the shoots cut at the soil line. Soil will be gently removed from the roots. A soil sample will be collected and nematodes extracted using elutriation and centrifugation. For reniform and root-knot nematodes, roots will be shaken in NaOCl to collect nematode eggs. Shoot and root weight will be recorded. For burrowing nematodes, a subsample of roots will be placed in the mist chamber to extract nematodes. Nematodes in the soil and the roots will be counted using a microscope. Shoots and roots will be dried to constant weight and weighed. Plant growth, nematode population density, and nematode reproduction from the experimental repeats will be tested for homogeneity of variance and when similar combined into a single data set. Data will be subjected to analysis of variance with mean separation procedures when appropriate.For experiments conducted in the field, plots will be established. Plot size will be dependent upon the area available and cooperator constraints. One research focus will be on mint as a living mulch to enhance the soil health and provide added income. New nematicides will be evaluated in field plots also. In general, each treatment will be replicated at least 3 times. The preferred experimental design will be a random complete block design, but split- or strip-plot designs will be used were constraints require more complex designs to be used. The crop will be planted and managed according to producer practices. Crops will be grown for a full cycle and data collected on nematode populations at 3-month intervals. Yield will be recorded at harvest. Soil samples will be collected at determined intervals and nematodes extracted using elutriation and centrifugation. The nematodes in each sample will be identified to trophic group and nematode community parameters such as richness, structure index, and enrichment index calculated. Test appropriate statistical analysis will be conducted. Plant-parasitic nematode population densities will be subjected to regression and correlation analysis. Crop yield will be subjected to analysis of variance and means separated where appropriate.Investigate biological aspects of plant-parasitic and entomopathogenic nematodes to exploit for soil health management: This objective will be accomplished through laboratory experiments, field sampling, and surveys. The genetic diversity of renifrom nematode will be elucidated using microsatellite markers (Arias et al., 2009; Fadal, unpublished). Populations from across the state will be collected and DNA extracted, amplified, and sequenced. The banding patterns and sequences will be compared. Pedigree analysis will be used to determine the relation between populations calculated.Other experiments will determine the presence of nematodes in Hawaii. Surveys of forests, agricultural fields, and urban areas will be conducted across islands. Nematodes will be collected from the soil via elutriation and centrifugation. Nematodes in the roots will be extracted in a mist chamber or by shaking in NaOCl for eggs. Understanding the nematode diversity in a healthy soil ecosystem is necessary to evaluate and interpret the nematode community of an agricultural field.The focus on EPN will be to enhance the efficacy of low number EPN foliar applications. Steinernema feltiae will be applied with various ultraviolet radiation protectants and EPN survival and infectivity compared to untreated EPN. EPN will be applied with desiccant protectants to enhance their survival also. EPN will be treated with commercial products such as Barricade, exposed to the air for set periods of time, and then compared for infectivity of insect larvae. Individual experiments will consist of treatments replicated at least 5 times and experiments repeated at least once. Results will be analyzed for variance. Local isolates of Oscheius sp. (Bisel, Myers and Sipes, unpublished) will be characterized for their associated bacteria by isolated pure cultures of bacteria from infected cadavers and directly from the nematodes. The 16S rRNA bacterial gene will be extracted, amplified and sequenced. Comparisons will be made to existing sequences for identification. The bacteria will be inoculated into mealworm larvae to test lethality. Mealworm larvae will also be feed a diet containing the bacteria. Larval mortality will be recorded and compared to untreated controls and Photorhabditis controls. These local isolates may provide an effective, locally-available alternative EPN for use as biological control.Disseminate information on soil health management: The dissemination of information will employ multiple platforms. Results of the research will be presented orally, electronically, and in print. Presentations will be made to growers during field days, and to scientists at annual society meetings. Journal articles will be prepared and submitted for publication. The Pineapple News, the official newsletter of the Pineapple Working Group, will be published as a venue for pineapple growers and researchers to report on pineapple production challenges and successes. Webpages will be created to highlight findings as projects develop.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:The target audience for this project is agricultural producers, agricultural regulators at the state and federal level, and other scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided training opportunities for one undergraduate and one graduate student. How have the results been disseminated to communities of interest?The results and findings have been disseminated to fellow scientists. A poster was presented at a professional meeting. The abstractof thepresentationis in press. Full manuscripts are being prepared for submission to peer-reviewed journals. Several other abstracts were submitted but the meetings were delayed because of the COVID-19 pandemic. What do you plan to do during the next reporting period to accomplish the goals?Greenhouse and field experiments will be undertaken. Manuscripts will be drafted and after internal review, submitted for publication.

Impacts
What was accomplished under these goals? Diseases caused by nematodes affect the health of native plants and their failure to establish when reintroduced into native ecosystems. The host status of native plants to the plant-parasitic nematodesMeloidogyne javanicaandRotylenchulus reniformiswas determined. In a series of greenhouse experiments, cuttings ofIpomea pes-caprae brasiliensis, Sida fillax, Myoporum sandwicense, andVitex rotundifoliaand seedlings ofScaevola taccadaandPrichartidiata sp.were inoculated withM. javanicaorR. reniformis. M. javanicawas not tested onI. pes-caprae brasiliensisandMyoporum sandwicense. R. reniformiswas not evaluated onS. taccada. Tomato seedlings were used as a comparative host forM. javanicaand cowpea seedlings forR. reniformis. Each test had 4 plants and was repeated twice. Three months after inoculation, plants were collected, roots shaken in NaOCl, and nematode reproduction calculated. Nematode reproduction on tomato and cowpea was > 1 in all experiments.Prichartidiata, S. fillax,andV. rotundifoliahad reproductive factors < 1 for both nematodes.M. sandwicensehad a reproductive factor < 1 forM. javanica. S. taccadahad a reproductive factor < 1 forR. reniformis. ForR. reniformis, I. pes-caprae brasiliensishad a reproductive factor > 1.Prichartidiatasp., S. fillax, M. sandwicense, S. taccada, andV. rotundifoliaare not good hosts to either nematode species. Further research on other native plants will give better understanding of the potential impact plant-parasitic nematodes have on reforestation.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Myers, R., Bushe, B., Mello, C., Lichty, J., Hara, A., Wang, K.-H., and Sipes, B. 2020. Yield increases in burrowing nematode-infested anthurium with fluopyram and trifloxystrobin applications. HortTechnology 30:603-607. https://doi.org/10.21273/HORTTECH04648-20
• Type: Other Status: Awaiting Publication Year Published: 2020 Citation: Wong, L. and Sipes, B. 2020. Host status of the plant-parasitic nematodes Rotylenchulus reniformis and Meloidogyne javanica on six Hawaiian native plants species. Phytopathology 110: in press

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:The target audience for this project is agricultural producers,agriculturalregulators at the state and federal level, and other scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided training opportunities for one undergraduate and one graduate student. The project also provided opportunities for undergraduate students outside the University of Hawaii during interactions with collaborators in Guatemala. How have the results been disseminated to communities of interest?The results and findings have been disseminated to fellow scientists. Poster and oral papers have been presented at professional meetings.Abstracts of these presentations are in press. Full manuscripts are being prepared for submission to peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?Greenhouse and field experiments will be undertaken. Manuscripts will be drafted and after internal review, submitted for publication.

Impacts
What was accomplished under these goals? Diseases caused by fungi, viruses, bacteria, and nematodes affect the health of native plants and can weaken their reintroduction into native ecosystems. The objective of this research was to document the host status of Meloidogyne javanica, a root-knot nematode, and Rotylenchulus reniformis, the reniform nematode, on native plants used in the landscape. In a series of greenhouse experiments, rooted cuttings of Ipomea pes-caprae brasiliensis, Sida fillax and Vitex rotundifolia and seedlings of Prichartidiata sp. were inoculated with eggs of M. javanica or mixed vermiform and eggs of R. reniformis. M. javanica was not tested on I. pes-caprae brasiliensis. Tomato seedlings were used as a comparative host for M. javanica and cowpea seedlings for R. reniformis. Each test had at least 4 plants and was repeated twice. Three months after inoculation, plants were collected, roots shaken in NaOCl to extract eggs, and nematode reproduction calculated. Nematode reproduction on tomato and cowpea was greater than1 in all experiments. Prichartidiata, S. fillax, and V. rotundifolia and had reproductive factors less than one for both nematodes. For R. reniformis, I. pes-caprae brasiliensis had a reproductive factor greater than 1. Prichartidiata, S. fillax, and V. rotundifolia are not good hosts to either nematode species. Ipomea pes-caprae brasiliensis is an excellent host for R. reniformis. As part of the USAID's Horticulture Innovation Laboratory goal to alleviate nutrition and food insecurity, this collaborative research was conducted in smallholder potato production areas in Huehuetenango and Xela in the Highlands of Guatemala. These regions have soil health and plant-parasitic nematode management problems. The Huehuetenango region is at 3,200 m to 3,353 m altitude laying over Mollisol soil group (class) and the Xela region is at 2,896 m over Andisols. An experiment was conducted in each region over two years to answer multiple questions. In each region, the effects of amending soils either with or without bio-mix (BioCopia) and 0, 318, or 454 kg of composted chicken manure at eight locations were tested. The bio-mix consisted of Guatemalan isolates of Purpureum and Bacillus applied at 1.8 kg/m2 to suppress harmful nematodes. This presentation reports on the effects of these treatments on nematode community structure (NCS), potato yield and percent organic carbon (C) and nitrogen (N), the combination of which indicates the overall soil health conditions. Nematodes were extracted from 100 cm3 of soil, fixed in double TAF solution at USAC and enumerated. Nematodes were identified into trophic and colonizer-persister (c-p) groups and data computed to reveal the soil food web (SFW) structure and function. Soil C and N were measured. There was no significant treatment effect on either the enrichment or structure scales of the SFW during the growing season at either location. The only exception was that the SFW structure was different between years in the high rate without the bio-mix. The overall SFW structure of both soil groups indicates Quadrant C- needing biological activity for nutrients to be released. Herbivores and bacterivores were the abundant trophic groups and c-p 1s were the least abundant in both soil groups, suggesting that the soils have similar SFW structure. Potato yield was slightly higher in the Andisol fields; whereas, C:N ratio was higher in the Mollisol fields. The data suggest that the soils may have different SFW functions, the cause-and-effect of which is yet to be determined.Cysts were extracted from 100 cm3 of soil at-planting, midseason and at-harvest using acetone flotation methods and quantified. Cyst population density increased in both soils, suggesting that the treatments were not effective. Potato yield increased in Andisols and decreased in Mollisols by about 5%. Organic matter did not change in Andisols, but increased in Mollisols. Cyst population density was very high before the treatments were initiated in both soil groups. A combination of the cyst, C:N ratio and potato yield data suggest that the Andisols are likely to benefit more from soil amendments than the Mollisols, which are high in organic matter.In addition, the technical efficiency of the smallholder growers within and across regions of potato production is low. Astochastic frontier production function for the locations attemptedto identify the factors that determine technical inefficiency. The model shows that technical inefficiency contributes 58% of production variability among potato farmers. The average technical efficiency is at 42%. In addition, there is a considerable variation in technical efficiency between four locations. Hence, there is a considerable room for the implementation of best agricultural practices for potato farming system in the Western Highlands of Guatemala. The estimated inefficiency model indicates that gender is a significant factor, which contributes to increase technical efficiency. This finding has vital policy implications for formulating an innovative rural development strategy which integrates gender into rural development planning in Guatemala. Likewise, this paper suggests that an increase in technical efficiency leads to improve productivity in potato cultivation and thereby increases farm household income. Thus, the findings provide policy insights for formulating a rural development strategy which, enhances productivity through improving technical efficiency in potato farming. It is our opinion that such a development strategy will assist poverty reduction and improving food security among potato farmers.

Publications

• Type: Book Chapters Status: Published Year Published: 2018 Citation: Sipes, B.S. and Chinnasri, B. 2018. Nematode parasites of pineapple. in Plant-parasitic nematodes in subtropical and tropical agriculture. 3nd edition. R.A. Sikora and J. Bridge, eds. CAB International, Oxfordshire, UK.
• Type: Book Chapters Status: Published Year Published: 2018 Citation: Sipes, B. and Pires de Matos, A. 2018. Pests, Diseases and Weeds. in 2018. The Pineapple, 2nd Edition: Botany, Production and Uses. G.M. Sanewsk et al., eds. CAB International.
• Type: Book Chapters Status: Published Year Published: 2018 Citation: Sipes, B. and Myers, R. 2018. Plant-parasitic nematodes in Hawaiian agriculture. In Plant parasitic nematodes in sustainable agriculture of North America. Vol. 1 - Canada, Mexico and Western USA. S.A. Subbotin and J.J. Chitambar, eds. Springer. ISBN:978-3-319-99584-7
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Kandouh, B.H., Hasan, A.E., Abd-Al-Rasoul, A.M., and Sipes, B.S. 2019. Screening for susceptibility and tolerance to Meloidogyne incognita and M. javanica in okra cultivars in Iraq. Arab Journal of Plant Protection 37:279-285. http://dx.doi.org/10.22268/AJPP-037.3.279285
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Lau, J-W., Marahatta, S.P., Ragone, D., Wang, K-H., and Sipes, B.S. 2018. Plant-parasitic nematodes associated with breadfruit, Artocarpus altilis, in Hawai?i. Nematropica 48:172-178.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Lau, J-W., Sipes, B., Wang, K-H., Marahatta, S., and Ragone, D. 2018. First report of Pratylenchus coffeae on breadfruit (Artocarpus altilis) in the United States. Plant Disease 102:1861. doi.org/10.1094/PDIS-02-18-0242-PDN.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Mishra, S., Wang, K-H., Sipes, B.S., and Tian, M. 2018. Induction of host-plant resistance in cucumber by vermicompost tea against root-knot nematode. Nematropica 48:164-171.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Chan, C., Widanage, R., Sipes, B., Melakeberhan, H., Sanchez, A., and Mejia, A. 2019. Enhancing agricultural productivity and gender contribution: A case of potato cultivation in Western Guatemala. Western Agricultural Economics Association, Coeur dÿ¢ÿ¿ÿ¿Alene, ID.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2019 Citation: Kakaire, S., Sanchez-Perez, A., Sipes, B.S., Lee, C-L., Sacbaja, A., Chan, C., and Melakeberhan, H. 2019. Integrated nematode and soil health management in the Western Highlands of Guatemalan potato production soils: I ÿ¢ÿ¿ÿ¿ similarities and differences in soil food web structure and function. Journal of Nematology 51:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2019 Citation: Sanchez-Perez, A., Alvarez, G.I., Sipes, B.S., Kakaire, S., Lee, C-L., Sacbaja, A., Chan, C., and Melakeberhan, H. 2019. Integrated nematode and soil health management in the Western Highlands of Guatemalan potato production soils: II ÿ¢ÿ¿ÿ¿ integrated efficiency of soil amendments. Journal of Nematology 51:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2019 Citation: Waisen, P., Wang, K-H., Cheng, Z., and Sipes, B.S. 2019. Susceptibility of brassica cover crops to Meloidogyne spp: An opportunity to enhance biofumigation effects. Journal of Nematology 51:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2019 Citation: Widanage, R., Chan, C., Mejia, A., Sanchez, A., Sipes, B.S., Sacbaja, A., and Melakeberhan, H. 2019. Integrated nematode and soil health management in the Western Highlands of Guatemalan potato production soils: III ÿ¢ÿ¿ÿ¿ Enhancing technical efficiency of growers. Journal of Nematology 51:in press.