Search Results (10)

Many microbial agents, such as Bacillus amyloliquefaciens, have been reported to promote the growth of plant roots, which may enhance the uptake of systemic pesticides by plant roots. Through experimental methods, such as microscopic observation and HPLC (High Performance Liquid Chromatography) detection, the colonization behavior of B. amyloliquefaciens HN11 in sweet potato rhizosphere and its effects on sweet potato growth and fosthiazate uptake were studied. The results show that B. amyloliquefaciens HN11 could effectively colonize the rhizosphere of sweet potatoes and significantly promote the growth of sweet potato roots, leading to increase the yield of sweet potatoes. Moreover, the colonization of B. amyloliquefaciens HN11 promoted the absorption of fosthiazate by sweet potato roots under drip irrigation. The control efficiency against root knot nematodes of sweet potato also improved under this management approach. In summary, drip application of fosthiazate to sweet potato roots inoculated with B. amyloliquefaciens HN11 revealed a new approach to insecticide application. This method could improve the effective utilization rate of fosthiazate and the control efficiency of root knot nematodes, help farmers increase production and income, be environmentally friendly and meet the requirements of sustainable development. This study provides new references for the application direction of microbial agents. Full article

Myzus persicae Sulzer (Hemiptera: Aphididae) is a pivotal pest affecting various vegetables, fruits, crops, and ornamentals. The primary M. persicae management strategy involves insecticide use. In this study, the toxicity and efficacy of bifenthrin, fenitrothion, fosthiazate, acetamiprid, spirotetramat, afidopyropen, and flonicamid against M. persicae were evaluated under laboratory and greenhouse conditions using the leaf dip method. Laboratory bioassay results revealed that M. persicae exhibited susceptibility to moderate resistance levels for bifenthrin [resistance ratio (RR): 3.00–21.50], fenitrothion (3.13–25.31), fosthiazate (3.00–20.00), and acetamiprid (2.00–14.50), as well as susceptibility to low resistance levels for spirotetramat (0.75 to 6.63). Additionally, M. persicae was susceptible to flonicamid (0.31–1.72) and afidopyropen (0.67–2.00). Furthermore, laboratory bioassays revealed that the Al-Dhabia M. persicae field population showed the highest resistance levels to all tested insecticides compared with other tested field populations, which guided the examination of insecticide field performance under greenhouse conditions. In the greenhouse, most insecticides demonstrated high efficacy (>90%) against M. persicae with enduring effects, except for bifenthrin, which began to lose effectiveness 10 days post-application. In conclusion, M. persicae displayed overall susceptibility to most tested chemical classes, and the prolonged efficacy of these insecticides in the field reinforces their effectiveness in controlling this pest species. To maintain this control level, the registration of novel insecticides such as flonicamid and afidopyropen in Saudi Arabia is imperative, expanding the repertoire of effective chemical tools for M. persicae control. Additionally, a rotational approach to using all effective chemical classes is crucial to preventing or delaying resistance development in M. persicae. Full article

The nematicidal potential of the yeast Papiliotrema terrestris strain PT22AV (YSY) was investigated against the root nematode (RKN) Meloidogyne incognita in in vitro bioassays on infective juveniles (J2) and experiments on tomatoes in pot and greenhouse conditions. The J2 nematodes were exposed to YSY solutions for 19 days, using abamectin (ABA), fosthiazate (FOS) and distilled water as controls. In the experiments on potted and greenhouse tomatoes, 0.5 and 1 kg ha⁻¹ doses of YSY were tested in comparison to ABA, biocontrol agents Purpureocillium lilacinus strain 251 (PUL) and Bacillus firmus strain 1-1582 (BAF), a plant biostimulant/fertilizer (ERG) and the nematicide Fluopyram (FLU). J2’s viability was affected by YSL after 7 days, decreasing to zero on the 15th exposure day, while ABA and FOS resulted in 83 and 100% J2 mortality within 24 h. Only the 1.0 kg ha⁻¹ dose of YSY was able to significantly reduce the final nematode population in soil and gall formation on tomato roots, without significant differences from PUL and BAF. All treatments in comparison also resulted in a significant increase in tomato growth and crop yield, except for 0.5 kg ha⁻¹ of YSY. Data indicated that YSY could represent an additional tool for organic and integrated RKN management. Full article

Plant-parasitic nematodes pose a serious threat to crops and cause substantial financial losses due to control difficulties. Tioxazafen (3-phenyl-5-thiophen-2-yl-1,2,4-oxadiazole) is a novel broad-spectrum nematicide developed by the Monsanto Company, which shows good prevention effects on many kinds of nematodes. To discover compounds with high nematocidal activities, 48 derivatives of 1,2,4-oxadiazole were obtained by introducing haloalkyl at the 5-position of tioxazafen, and their nematocidal activities were systematically evaluated. The bioassays revealed that most of 1,2,4-oxadiazole derivatives showed remarkable nematocidal activities against Bursaphelenchus xylophilus, Aphelenchoides besseyi, and Ditylenchus dipsaci. Notably, compound A1 showed excellent nematocidal activity against B. xylophilus with LC₅₀ values of 2.4 μg/mL, which was superior to that of avermectin (335.5 μg/mL), tioxazafen (>300 μg/mL), and fosthiazate (436.9 μg/mL). The transcriptome and enzyme activity results indicate that the nematocidal activity of compound A1 was mainly related to the compound which affected the acetylcholine receptor of B. xylophilus. Full article

Root-knot nematode disease seriously threatens the production of Rui yams, making it important to explore effective management strategies, including the optimal time for disease control and efficient application techniques. In this study, we monitored the dynamics of a root-knot nematode J2 population in the soil using field sampling; moreover, we investigated the dynamics of root-knot nematode disease using a field sampling and visual in situ device based on identifying species of root-knot nematodes in Rui yams. Additionally, experiments pertaining to optimal application time and techniques were conducted in Ruichang and Nanchang. This is the first study to propose that chemical control should be optimally timed, with one application administered at the time of yam seedling flush, and another given approximately 60 days later. Applications of a 41.7% fluopyram suspension (1426 g.a.i./hm²) and a 30% fosthiazate microencapsulated suspension (2925 g.a.i./hm²) achieved disease control effects of 81.56–83.15% and 75.95–78.42%, respectively. Additionally, the comparative analysis demonstrated that using uniform root layer application technology at the optimal time produces a control effect exceeding 80%, which is significantly higher than conventional techniques such as drip irrigation and root irrigation. These results provide theoretical and technical support for the efficient control of root-knot nematode disease in Rui yams. Full article

Losses caused by phytoparasitic nematodes in crops depend directly on their soil densities at the start of the crop, so reducing their populations before planting is the main aim of nematological management. Efficacies in reducing Meloidogyne soil populations of soil disinfestation methods, such as agrochemicals, botanicals, or biosolarization were estimated on multiple field trials conducted over fourteen years in intensive horticultural crops. Soil nematode populations were reduced by 87 to 78% after fumigation with 1,3-dichloropropene + chloropicrin and dimethyl-disulphide, respectively. Non-fumigant nematicides such as azadirachtin, dazomet, fenamiphos, fluopyram, fosthiazate, metam-sodium, and oxamyl showed efficacies ranging from 51 to 64%, whereas the efficacy of natural products, such as abamectin, garlic extracts, or essential oils was 41 to 48%. Biosolarization with chicken manure had an efficacy of 73%. An economic cost-benefit study of nematode management methods was performed for seven vegetable–M. incognita pathosystems. Fumigation with 1,3-dichloropropene + chloropicrin and biosolarization with chicken manure were the only treatments able to reduce RKN populations above 1000 and 750 J2 per 100 cm³ of soil, respectively, to levels below the nematode economic damage threshold, keeping profitability. Fumigation was able to manage RKN soil densities up to 350 J2 per 100 cm³ of soil in most susceptible crops as aubergine or cucumber and up to 1000 J2 per 100 cm³ of soil for more tolerant crops, such as other cucurbits, pepper, or tomato. Other nematicidal treatments were not able to reduce RKN populations above 200–300 J2/100 cm³ of soil below the economic thresholds but were profitable when RKN densities were below the limits of 200–300 J2/100 cm³ of soil. Full article

Grammicin, a polyketide metabolite produced by the endolichenic fungus Xylaria grammica KCTC 13121BP, shows strong nematicidal activity against Meloidogyne incognita. This study was performed to elucidate the grammicin biosynthesis pathway of X. grammica KCTC 13121BP and to examine the nematicidal activity of the biosynthesis intermediates and derivatives against M. incognita. Two grammicin biosynthesis intermediates were isolated from a T-DNA insertion transformant (strain TR-74) of X. grammica KCTC 13121BP and identified as 2-(hydroxymethyl)cyclohexa-2,5-diene-1,4-dione (compound 1) and 2,5-dihydroxybenzaldehyde (compound 2), which were also reported to be intermediates in the biosynthesis pathway of patulin, an isomer of grammicin. This indicates that the grammicin biosynthesis pathway overlaps almost with that of patulin, except for the last few steps. Among 13 grammicin biosynthesis intermediates and their derivatives (except grammicin), toluquinol caused the highest M. incognita J2 mortality, with an LC_{50/72 h} value of 11.13 µg/mL, which is similar to grammicin with an LC_{50/72 h} value of 15.95 µg/mL. In tomato pot experiments, the wettable powder type formulations (WP) of toluquinol (17.78 µg/mL) and grammicin (17.78 µg/mL) also effectively reduced gall formation on the roots of tomato plants with control values of 72.22% and 77.76%, respectively, which are much higher than abamectin (16.67%), but lower than fosthiazate (100%). The results suggest that toluquinol can be used directly as a biochemical nematicide or as a lead molecule for the development of new synthetic nematicides for the control of root-knot nematode diseases. Full article

The cyst nematodes of the genera Heterodera (HET) and Globodera (GLO) are among the most damaging obligate plant parasitic nematodes (PPNs) that parasitize cereals, rice, potatoes and soybean. In the absence of resistant crops, soil fumigation of pesticides provides a good strategy for population control. However, synthetic nematicides can cause negative environmental and public health impacts and are feared to lead to the development of resistance and immunity. The use of essential oils (EOs) could be a viable environmentally friendly alternative, which has been poorly explored on cyst nematodes but has shown very good results on other PPNs. The present work reviews the existing bibliography on the biological activity of EOs against GLO and HET. EOs from Allium sativum, Eucalyptus globulus, and Salvia officinalis were the most active against GLO egg hatching. The EOs extracted from Hyssopus cuspidatus, Kaempferia galanga, Menthacanadensis, Ocimum basilicum, and Valeriana amurensis had the highest activity against HET J2 juveniles. Ethyl p-methoxycinnamate, a phenylpropanoid ester, was the EO volatile with the highest toxicity against HET, showing lower EC₅₀ values than the nematodicide fosthiazate. The study of EOs against cyst nematodes is still preliminary in comparison to other PPNs. Future works must expand this line of research and explore greener practices in cyst nematode pest management. Full article

The potato cyst nematode Globodera pallida is a major pest of the potato crop. Abamectin is a biological pesticide showing high nematicide activity, but its efficacy to control G. pallida has not been investigated to date. In this study, combination of different abamectin concentrations ranging from 1.125 to 36 µg/mL x exposure times from 24 to 384 h were tested on the nematode in a hatching test. Abamectin induced mortality with LD₅₀ value in the range of 13.23 (after 24 h) to 2.90 µg/mL (after 384 h). A glasshouse experiment was also performed in pots filled with soil infected with G. pallida in the presence of sprouted potato tubers cultivar “Spunta”. Abamectin at 4.5, 9.0, 18.0 and 36.0 µg/mL was used in comparison with nematicide fosthiazate. The doses of 18 and 36 µg/mL significantly reduced number of eggs, juveniles, cyst/g soil and reproduction rate in comparison to both untreated control and fosthiazate treatment. Soil applications of abamectin provided significant G. pallida control with LD₅₀ and LD_99.9 of 14.4 and 131.3 µg/mL, respectively. These results indicate the efficacy of abamectin to control G. pallida on potato crops and its potential use in organic agriculture or in an integrated pest management program. Full article

The use of nematicides with reduced toxic side-effects against non-target free-living nematodes is a favorable option for farmers to control plant-parasitic nematodes. The nematicide fluensulfone was registered in several countries for the control of the root-knot nematodes, Meloidogyne spp. among other plant-parasitic nematodes. This study aimed to evaluate the nematicidal activity of fluensulfone against non-target nematode fauna in four field experiments, each under different conditions (soils types and plant hosts). Nematodes extracted from soil samples were classified and counted based on their morphological characters. Fluensulfone significantly reduced damage caused by root-knot nematodes to tomato and sweet potato plants, while overall non-target free-living nematode population densities were maintained at the same level as those in control. Different diversity indices (e.g., Shannon-Wiener H’, Simpson’s D, species richness, evenness J’, maturity indices) and principal component analyses in the four experiments showed that fluensulfone treatment kept a similar diversity level of non-target free-living nematode fauna to that of the non-treated control. The results suggested that fluensulfone may have minimal impact to free-living nematode fauna in both population density and diversity when the nematicide was applied to control Meloidogyne spp. Full article