Walnut (Juglans regia L.) is an economically important woody nut and edible oil tree all over the world. However, walnut production is limited by walnut anthracnose, which is a disastrous disease that causes significant yield losses. Studying the etiology of anthracnose on walnut and the pathogens’ virulence and sensitivities to fungicides would be beneficial for effective control. This study was conducted to identify the pathogen of walnut anthracnose and reveal the population diversity of pathogens through virulence, sensitivities to fungicides, and genetic variation. A total of 13 single-spore Colletotrichum isolates were collected from walnut anthracnose-diseased fruits and leaves from 13 walnut commercial orchards in Henan, Hubei, Shandong, and Shaanxi provinces in China. The isolates were identified as Colletotrichum gloeosporioides sensu stricto (s.s.) according to multilocus phylogenetic analyses (internal transcribed spacer, actin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase), morphological as well as cultural characters, and pathogenicity. When the same walnut tissue was inoculated with different isolates, the disease lesion size was different. The results showed that the virulence of all isolates was considerably different, and the differences were not correlated with geographic origins. The virulence to walnut leaves and fruits inoculated with the same isolate was significantly different. Based on the virulence to walnut leaves and fruits, the 13 isolates were divided into three groups. Virulence of 69.2% of the isolates to walnut fruits was higher than that to leaves; 15.4% of isolates had no difference in pathogenicity, and the virulence to walnut leaves was higher for 15.4% of isolates. Tebuconazole, difenoconazole, flusilazole, and carbendazim inhibited the growth of fungal mycelia, and the concentration for 50% of maximal effect (EC50) values were 0.4 to 20.5, 0.6 to 2.6, 0.2 to 1.6, and 0.002 to 0.2 µg/ml, respectively, with average values of 6.5 ± 6.9, 1.5 ± 0.6, 0.9 ± 0.4, and 0.1 ± 0.05 µg/ml, respectively. All isolates were more sensitive to difenoconazole, flusilazole, and carbendazim than tebuconazole (P < 0.01). Isolate sensitivities to the same fungicide were different. Isolates SL-31 and TS-09 were the least sensitive to carbendazim and tebuconazole, respectively, and the resistance ratios were 87.3 and 51.6, respectively. Sensitivities to difenoconazole and flusilazole were largely consistent among all isolates, and the resistance ratios were from 1 to 4.6 and from 1 to 7, respectively. Therefore, difenoconazole and flusilazole could be chosen for disease control. The differences of pathogenicity and fungicide sensitivity were not correlated with geographic regions. These results indicated that there was high intraspecific diversity of populations in C. gloeosporioides s.s. that caused walnut anthracnose. For effective management, the targeted control strategy should be implemented based on the different geographic regions.

the pine needle gall midge, Thecodiplosis japonensis Uchida et inouye, is a newly invasive pest in china that mainly harms Pinus thunbergii and P. densiflora. the occurrence and damage caused by T. japonensis in pure stands of P. thunbergii were investigated, and the needle growth and needle compound content were measured. Based on the above steps, the growth dynamics of galls and chemical defense response of P. thunbergii to attack by the gall midge were revealed. the results showed that the adults of T. japonensis in Qingdao city, china, emerged from the end of May to late July, with a peak in mid-June. needles of P. thunbergii began to differentiate in late June and stopped growing in mid-September. The length of infested needles was 60.17% less than that of healthy needles. On average, there were 9 ± 4 larvae in each gall, 22 at most and 1 at least. The number of larvae within a gall had no significant effect on the size of the gall or larvae. Compared with that in the ungalled tissues, the content of amino acids in the galled pine needle tissues increased by 40.83%, while the content of total polyphenols, tannins, carotenoids, total triterpenes, total alkaloids and other secondary substances decreased to varying degrees, which was favourable for the growth and development of the T. japonensis larvae. There are approximately one million named insects and more than 500,000 plants on Earth, accounting for more than half of the total global biodiversity 77. During the long-term process of natural selection, plants and insects are closely related in regard to nutrition, reproduction, protection, defence and diffusion. Plants provide food and habitat for insects, but insects also provide many benefits to plants, such as seed dispersal and pollination 37. There are many ways by which insects obtain nutrition from plants. Some insects, such as beetles, moths, and wasps, directly eat the leaves, stems and roots of plants, which affects the absorption of nutrients and the performance of photosynthesis by plants 26,54,74. Some suck the sap from plant tissue, such as aphids, red spiders, and whiteflies 13,19,28 , which causes the loss of green colouration, the deformity of plant tissue and plant death. In general, host plants respond positively to damage caused by pests. For instance, almost all secondary metabolites, including nitrogenous compounds (such as alkaloids and non-protein amino acids), terpenes (such as monoterpenes and diterpenoids), and phenols (such as monophenols and flavonoids), may be produced in large quantities in plant tissues due to insect attack 2,9,16,20,34,41,73. The insects that can induce plants to produce galls are called gall-forming insects and represent a large group of phytophagous insects. Galls on host plants vary morphologically among different insects 27 , these morphological differences are considered to represent the adaptability of the gall-forming insects to the environment 5,27,33. Six hypotheses have been proposed to explain this phenomenon, including the nonadaptive hypothesis,...

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The red-fleshed apple (Malus niedzwetzkyana) produces a colored fruit and rich anthocyanins and it has become popular among consumers in Shandong (Yang et al 2020). In recent years, anthracnose diseases have been reported in red-fleshed apple orchards and nurseries in Shandong province, China. The incidence of anthracnose in the red-fleshed apple plantings ranges from 50-90%. Initially, anthracnose lesions on fruit begin as sub-circular shaped, sunken, pale brown. Over time black lesions enlarged and coalesced into large necrotic areas. The sunken centers of mature lesion became filled with slimy pink sporulation. In September 2015, fifteen fruit with anthracnose symptoms and sporulation were collected, and 11 single-spore isolates were obtained. Three representative isolates (JNTW11, JNTW2, JNTW33) were used for morphological and molecular characterization. On PDA, the colonies were initially white and turned into pale brown in three days. Orange-brown pigmentation was produced near the center on the reverse. Aerial mycelium was cottony, dense, pale white to pale gray. Acervuli developed visible orange-pink conidial masses. Conidiophores were colorless, septate, not branched or branched at the base. Conidia were 1-celled, hyaline, subcylindrical, oblong, attenuated with blunt ends, and the average size was 16.7 ± 1.5 × 6.1 ± 0.9 μm (n = 50). Appressoria were brown, obovoid or irregular, 9.2 ± 1.6 × 8.0 ± 1.8 μm (n = 20). The morphological characters matched the descriptions of Colletotrichum gloeosporioides sensu lato (Cannon et al. 2008). Isolates JNTW11, JNTW2, and JNTW33 were subject to bioinformatic characterization by partial sequencing of 6 genetic loci including the ribosomal internal transcribed spacer (ITS), actin (ACT), beta-tub2 (TUB2), calmodulin (CAL), chitin synthase (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Weir et al, 2012). The ITS (MT577037, MT577040, MT577042), ACT (MT767712, MT767715, MT767717), TUB2 (MT767723, MT767726, MT767728), CAL (MT767689, MT767692, MT767694), CHS-1(MT767700, MT767703, MT767705), and GAPDH (MT767734, MT767737, MT767739) sequences were deposited in GenBank. The six sets of sequence data were concatenated “ITS-GAPDH-ACT-CHS-1-TUB2-CAL”, and the aligned sequences (2,007 bp) had 99.0% similarity to ex-type C. siamense ICMP18578. In a maximum likelihood phylogenetic tree, the highest log likelihood was -9148.55, and the isolates tested were in the C. siamense cluster with 96 % bootstrap support. Thus, the isolates were identified as C. siamense on the basis of multilocus phylogenetic analyses and morphological characters. To complete Koch’s postulates, several healthy red-fleshed apple fruit (‘Jiuhong’, 1 month prior to harvest) were inoculated using colonized and uncolonized hyphal plugs and a blank agar as a control. All inoculated fruit were placed in sterile tissue culture bottles containing 2 layers of wet paper towels at 28 °C under a 12 h light/dark cycle. All fruit developed anthracnose symptoms in 7 days while the controls did not develop any symptoms. The symptoms were similar to those collected from fruit in the field, and same fungus was re-isolated from the lesions. Presently it was known that C. acutatum, C. asianum, C. chrysophilum, C. cuscutae, C. fioriniae, C. fragariae, C. fructicola, C. gloeosporioides, C. godetiae, C. kahawae, C. karstii, C. limetticola, C. melonis, C. noveboracense, C. nymphaeae, C. paranaense, C. rhombiforme, C. salicis, and C. theobromicola could infect M. coronaria, M. domestica, M. prunifolia, M. pumila, and M. sylvestris worldwide. To our knowledge, this is the first report of C. siamense as a pathogen of M. niedzwetzkyana. This finding provides crucial information for the management of anthracnose disease in China.

The movement behavior of the pine needle gall midge (Thecodiplosis japonensis Uchida Et Inouye (Diptera: Cecidomyiidae)), an invasive species in China, was determined by using a tethered flight technique and digital videography in the laboratory. The flight distance, duration, and speed of females were compared at different ages (2–10 h) and ambient temperatures (17, 21, 26, and 30°C). Female flight distance and duration at 26°C were significantly greater than those at 17°C and 21°C. The age of T. japonensis did not significantly affect the three flight characteristics. For females at 2–10 h of age at 26°C and 70% RH, the maximum flight distance was 667.59 m; the longest flight time was 6,222.34 s; and the fastest flight speed was 0.44 m·s−1. For larvae wetted with water, the highest jump was 5.7 cm; the longest jump was 9.6 cm; and the greatest distance moved in 5 min was 27.13 cm, which showed that the active dispersal potential of larvae was very low.