First Report of Root-knot Nematode, Meloidogyne enterolobii on Passiflora edulis in Yulin, China.

Passion fruit (Passiflora edulis), a medicinal plant, was introduced into China in the early 19th century, is mainly cultivated in southern provinces (Liang et al. 2019). During March 2023, a survey was carried out and 167 samples were taken from passion fruit cultivated area in Yulin (22.6570263°E; 110.1765019°N) apart from the planting base appeared yellow leaves, stunted growth, and distinctive galls on the roots. Within the galls, Meloidogyne sp. females and egg masses were observed. From the rhizosphere soil, second-stage juveniles (J2) were extracted, and population density was 105/500 g soil. The species was determined to be Meloidogyne enterolobii based on morphological characteristics, including female perineal pattern, and genetic analyses. Female (n = 10) perineal patterns showed oval shape, with coarse and smooth striae, dorsal arch rounded to square, and lateral lines not distinct. The male head cap was high and rounded, with the head region only slightly set off from the body, knobs large, ovoid to rounded. The measurements of males (n = 10) included body length, 1,230.7 ± 244.94 (997 to 1,569) µm; a, 38.58 ± 7.8 (33.45 to 47.05) µm; c, 113.03 ± 26.22 (80.82 to 144.23) µm; stylet, 15.68 ± 1.1 (14.5 to 17.4) µm; spicules, 31.83 ± 2.84 (28.69 to 36.1) µm; tail, 11.09 ± 1.72 (8.02 to 13.38) µm; and gubernaculum length, 8.34 ± 0.28 (8.11 to 8.98) µm. Measurements of J2 (n = 20) included body length, 455.75 ± 44.94 (381 to 512) µm; a, 26.32 ± 3.89 (18.18 to 32.70) µm; c, 8.56 ± 1.2 (6.36 to 10.80) µm; stylet, 12.44 ± 0.76 (11.2 to 13.8) µm; DGO, 3.65 ± 0.54 (2.84 to 4.68) µm; tail, 53.89 ± 6.36 (39.8 to 62.2) µm; and hyaline tail terminus, 11.77 ± 2.83 (7.14 to 16.2) µm. These morphological characteristics are similar to those reported in the original description of M. enterolobii (Yang and Eisenback 1983). The sequences of the partial ITS region was amplified with V5367 (5'-TTGATTACGTCCCTGCCCTTT-3') and 26S (5'-TTTCACTCGCCGTTACTAAGG-3') primers (Vrain et al. 1992). The region between cytochrome oxidase subunit II (COII) and the 16S rRNA mitochondrial DNA (mtDNA COII) was also amplified with the primers C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') (Powers and Harris 1993) and MRH106 (5'-AATTTCTAAAGACTTTTCTTAGT-3') (Stanton et al. 1997). The ITS region yielded a fragment of 757 bp (OR072957) and mtDNA COII of 706 bp (OR078415). A BLAST search indicated the sequences were 100% identical to several sequences of M. enterolobii (MT406250, MH756127 and AY831967, MN269940, respectively). To confirm pathogenicity, 20 passion fruit (P. edulis Sim. f. flavicarpa) 30-day-old seedlings were transplanted into pots with an autoclaved mixture of sand and field soil (3:1) and maintained in the glasshouse at 25 ± 2°C with 65 ± 5% relative humidity. After eight weeks, fifteen plants were inoculated with 500 J2/pot (nematode culture collected from the original field), and another five uninoculated plants served as a control. Two months later, aboveground symptoms were similar to those observed in the field. Nematode reproduction occurred and root galls were observed. The reproduction factor (nematode final population density/initial population density) was 4.8. The disease caused by M. enterolobii was severe in Yulin city of Guangxi. Guangxi is an important area for passion fruit culture, with about 2000 ha, which is responsible for two-thirds of China production (Xing et al. 2020). This is the first record of P. edulis natural infection with M. enterolobii in the Yulin City of Guangxi, China.

First Report of Root-Knot Nematode Meloidogyne enterolobii on Antirrhinum majus in China.

Antirrhinum majus L. is a medicinal and ornamental herb commonly grown in China. In October 2022, A. majus plants were observed stunted in growth with yellowish leaves and containing a large number of galls on roots in a field in Nanning, Guangxi, China (N22°47'23.35″, E108°23'4.26). Ten samples were collected randomly from rhizosphere soil and roots of A. majus. Second-stage juveniles (J2) were isolated from fresh soil with a Baermann funnel, and a mean of 36 ± 2.9 per 500 cm3 of soil was recorded. Gall roots were dissected using a microscope, where 2+ 0.42 males per sample were recovered. The species was determined to be Meloidogyne enterolobii based on morphological characteristics, including the female perineal pattern, and DNA studies. Female perineal patterns and morphometric data were similar to the original description of M. enterolobii Yang and Eisenback 1983 from Enterolobium contortisilquum (Vell.) Morong in China (Yang and Eisenback 1983). The measurements of males (n = 10) included body length, 1600.7 ± 55.32 (1421.3 to 1924.3) µm; body diameter = 41.3 ± 0.80 (37.8 to 45.4) µm, stylt length = 20.5 ± 0.40 (19.1 to 22.2) µm, spicules length = 30.0 ± 0.47 (28.2 to 32.0) µm and DGO = 4.5 ± 0.3 (3.8 to 5.2) µm. Measurements of J2 (n = 20) included body length, 441.9 ± 5.42 (403.2 to 493.3) µm; body diameter = 16.6 ± 0.30 (14.4 to 8.7) µm, a = 26.8 ± 0.54 (21.9 to 31.2), c = 8.7 ± 0.27 (6.4 to 10.8), stylet length = 12.6 ± 0.17 (11.2 to 14.3) µm, DGO = 3.8 ± 0.10 (2.9 to 4.8) µm, tail length = 51.6 ± 1.27 (42.3 to 63.1) µm and hyaline tail terminus length = 11.7 ± 0.15 (10.2 to 13.1) µm. These morphological characteristics are similar to the original description of M. enterolobii (Yang and Eisenback 1983). Pathogenicity tests were conducted on A. majus 'Taxiti' plants directly germinated from seeds in a 10.5-cm-diameter pot filled with 600 ml of sterilized peat moss/sand (1:1, v/v) soil in the glasshouse. After 1 week, fifteen plants were inoculated with 500 J2/pot (nematode culture collected from the original field) and five uninoculated plants served as a control. After 45 days, aboveground parts of all inoculated plants showed symptoms similar to those observed in the field. No symptoms were observed on control plants. The RF value of the inoculated plants was determined by the method of Belair and Benoit (1996) 60 days after inoculation, and the average was 14.65. J2 were used in this test and sequenced on 28S rRNA-D2/D3, ITS, COII -16SrRNA 3 region and confirmed to be M. enterolobii. Species identification was confirmed by using polymerase chain reaction primers D2A/D3B (De Ley et al. 1999), F194/5368r (Ferris et al. 1993), C2F3/1108 (Powers and Harris, 1993). The sequences obtained GenBank accession numbers OP897743 (COII), OP876758 (rRNA) and OP876759 (ITS) were 100% similar to other M. enterolobii populations from China (MN269947), (MN648519) and (MT406251). M. enterolobii is a highly pathogenic species and has been reported in vegetables, ornamental plants, guava (Psidium guajava L.), and weeds in China, Africa and America (Brito et al. 2004; Xu et al. 2004; Yang and Eisenback 1983). The medicinal plant Gardenia jasminoides J. Ellis was also infected by M. enterolobii in China (Lu et al. 2019). Of concern is its ability to develop on crop genotypes carrying RKN resistance genes in tobacco (Nicotiana tabacum L.), tomato (Solanum lycopersicum L.), soybean (Glycine max (L.) Merr.), potato (Solanum tuberosum L.), cowpea (Vigna unguiculata (L.) Walp.), sweetpotato (Ipomoea batatas (L.) Lam.), and cotton (Gossypium hirsutum L.). Consequently, this species was added to the European and Mediterranean Plant Protection Organization A2 Alert List in 2010. This is the first natural infection report of M. enterolobii in Guangxi, China on the medicinal and ornamental herb A. majus. Acknowledgments This research was funded by the National Natural Science Foundation of China (31860492), Natural Science Foundation of Guangxi (2020GXNSFAA297076), and Guangxi Academy of Agricultural Sciences Fund, China (2021YT062, 2021JM14, 2021ZX24). References: Azevedo de Oliveira, S., et al. 2018. PLoS One 13:e0192397. Belair, G., and Benoit, D. L. 1996. J. Nematol. 28:643. Brito, J. A., et al. 2004. J. Nematol. 36:324. De Ley, P., et al. 1999. Nematol. 1:591-612. Ferris, V. R., et al. 1993. Fundam. Appl. Nematol. 16:177-184. Lu, X. H., et al. 2019. Plant Dis. 103:1434. Powers, T. O. and Harris, T. S. 1993. J. Nematol. 25:1-6 Vrain, T. C., et al. 1992. Fundam. Appl. Nematol. 15:563. Yang, B. and Eisenback, J. D. 1983. J. Nematol. 15:381.

Colletotrichum species associated with mango in southern China.

Mango (Mangifera indica L.) is an economically significant fruit crop in provinces of southern China including Hainan, Yunnan, Sichuan, Guizhou, Guangdong and Fujian. The objective of this study was to examine the diversity of Colletotrichum species infecting mango cultivars in major growing areas in China, using morphological and molecular techniques together with pathogenicity tests on detached leaves and fruits. Over 200 Colletotrichum isolates were obtained across all mango orchards investigated, and 128 of them were selected for sequencing and analyses of actin (ACT), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer (ITS) region, ß-tubulin (TUB2) genomic regions. Our results showed that the most common fungal isolates associated with mango in southern China involved 13 species: Colletotrichum asianum, C. cliviicola, C. cordylinicola, C. endophytica, C. fructicola, C. gigasporum, C. gloeosporioides, C. karstii, C. liaoningense, C. musae, C. scovillei, C. siamense and C. tropicale. The dominant species were C. asianum and C. siamense each accounting for 30%, and C. fructicola for 25%. Only C. asianum, C. fructicola, C. scovillei and C. siamense have previously been reported on mango, while the other nine Colletotrichum species listed above were first reports associated with mango in China. From this study, five Colletotrichum species, namely C. cordylinicola, C. endophytica, C. gigasporum, C. liaoningense and C. musae were the first report on mango worldwide. Pathogenicity tests revealed that all 13 species caused symptoms on artificially wounded mango fruit and leaves (cv. Tainong). There was no obvious relationship between aggressiveness and the geographic origin of the isolates. These findings will help in mango disease management and future disease resistance breeding.

Physiological Metabolic Responses of Ophraella communa to High Temperature Stress.

Considering the predicted rising temperatures under current climate change and heat wave scenarios, organisms are expected to suffer more intense and frequent thermal stress. Induced heat is accumulated by organisms and can cause a variety of physiological stress responses. Ophraella communa is an effective biological control agent of common ragweed, Ambrosia artemisiifolia, but the responses of this biocontrol agent to heat stress have not been fully elucidated and, therefore, its potential responses to climate change are uncertain. We investigated the physiological metabolism of subsequent O. communa adults after: (1) different developmental stages (egg, larval, pupal, and adult) were exposed to thermal stress for 3 h each day for 3, 5, 5, and 5 days, respectively (by stage); and (2) individuals were exposed to thermal stress throughout the egg-to-adult period for 3 h each day. The high temperatures of 40, 42, and 44°C were used to induce thermal stress. A control group was reared at 28 ± 2°C. The results showed that short- or long-term exposure to daily phasic high temperatures significantly decreased water and lipid contents and significantly increased glycogen and glycerol contents in all adults (i.e., after exposure of different stages or throughout the egg-to-adult period). However, the total sugar content significantly increased in adults after the eggs and larvae were exposed to brief short-term thermal stress. Compared to the control, the total sugar content was also significantly higher in the adults and pupae exposed to 44°C. Total sugar content in females increased significantly in response to long-term phasic thermal stress at 40°C. However, sugar content of males exposed to 44°C decreased significantly. After long-term phasic thermal stress, water and glycogen contents in males were significantly higher than in females; however, females had higher total sugar and lipid contents. Therefore, our study provides a basic understanding of the metabolic responses of O. communa to thermal stress and offers insights into its potential as a natural biocontrol agent against A. artemisiifolia during the summer season and under predicted climate change scenarios.

Effect of short-term high-temperature exposure on the life history parameters of Ophraella communa.

Extreme heat in summer is frequent in parts of China, and this likely affects the fitness of the beetle Ophraella communa, a biological control agent of invasive common ragweed. Here, we assessed the life history parameters of O. communa when its different developmental stages were exposed to high temperatures (40, 42 and 44 °C, with 28 °C as a control) for 3 h each day for 3, 5, 5, and 5 days, respectively (by stage). The larval stage was the most sensitive stage, with the lowest survival rate under heat stress. Egg and pupal survival significantly decreased only at 44 °C, and these two stages showed relative heat tolerance, while the adult stage was the most tolerant stage, with the highest survival rates. High temperatures showed positive effects on the female proportion, but there was no stage-specific response. Treated adults showed the highest fecundity under heat stress and a similar adult lifespan to that in the control. High temperatures decreased the F1 egg hatching rate, but the differences among stages were not significant. Negative carry-over effects of heat stress on subsequent stages and progenies' survival were also observed. Overall, heat effects depend on the temperature and life stage, and the adult stage was the most tolerant stage. Ophraella communa possesses a degree of heat tolerance that allows it to survive on hot days in summer.

Antioxidant Responses of Ragweed Leaf Beetle Ophraella communa (Coleoptera: Chrysomelidae) Exposed to Thermal Stress.

Ophraellacommuna LeSage is an effective biological control agent of common ragweed, Ambrosia artemisiifolia L., which competes with crops and causes allergic rhinitis and asthma. However, thermal stress negatively affects the developmental fitness and body size of this beetle. High temperatures cause a variety of physiological stress responses in insects, which can cause oxidative damage. We investigated the total protein content and activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and peroxidases (PODs) in O. communa adults when its different developmental stages were exposed to high temperatures (40, 42, and 44°C) for 3 h each day for 3, 5, 5, and 5 days, respectively (by stage), and a whole generation to high temperatures (40, 42, and 44°C) for 3 h each day. A control group was reared at 28 ± 2°C. Under short-term daily phasic high-temperature stress, total protein contents were close to the control as a whole; overall, SOD activities increased significantly, CAT activities were closer to or even higher than the control, POD activities increased at 40°C, decreased at 42 or 44°C; stage-specific response was also observed. Under long-term daily phasic high-temperature stress, total protein content increased significantly at 44°C, SOD activities increased at higher temperatures, decreased at 44°C; CAT activities of females increased at ≤42°C, and decreased at 44°C, CAT activities of males decreased significantly; POD activities of females increased at 40°C, decreased at ≥42°C, POD activities of males decreased at 44°C; and antioxidant enzymes activities in females were significantly higher than those in males. Antioxidative enzymes protect O. communa from oxidative damage caused by thermal stress.

Steinernema balochiense n. sp. (Rhabditida: Steinernematidae) a new entomopathogenic nematode from Pakistan.

A new species of entomopathogenic nematode (EPN) named Steinernema balochiense n. sp. belonging to the family Steinernematidae was isolated from Psidium guajava L., rhizophere soil samples of Balochistan, Pakistan. This new species belongs to the carpocapsae group. The new species can be separated from other described species by morphological and morphometrics characteristics as well as DNA sequence polymorphisms. This new nematode species is morphologically characterized by features of infective juveniles (IJ) and males. For the IJ average body length was (455; 415-528) µm, distance from anterior end to excretory pore (35; 32-38) µm, pharynx length (90; 85-98) µm, tail length (44.3; 40-51) µm, D% and E% values (39; 36-44) and (80; 70-92), respectively. For male specimens, the diagnostic characters included total body length (1330; 1135-1632) µm, gubernaculum length (44.4; 40-47) µm, D% (43.8; 40-51) and ratio of GS (63.8; 53-75). Morphological diagnostic traits for new species include the presence of a funnel shaped gubernaculum at the proximal end. S. balochiense n. sp. differs from infective stage juveniles of closest species S. nepalense by having 6 ridges vs 7 ridges in the lateral field. Molecular phylogenetic trees based on sequence of ITS-rDNA, D2D3 regions and the mitochondrial 12S rRNA gene supports the description of this nematode isolate as a new species.