Journal of Plant Diseases and Protection

Li, Hai-Lin; Zheng, Xia-Lin; Huang, Zong-You; Lu, Wen

doi: 10.1007/s41348-019-00296-8pmid: N/A

Diaphorina citri (Kuwayama) (Homoptera: Liviidae) is an important vector of citrus Huanglongbing, a serious threat to the development of citrus industry in China. Studies on the reproductive behavior of D. citri could contribute to understanding the crucial time to centrally control D. citri adults. The latest research results on the reproductive behavior of D. citri in recent years were reviewed, including the behaviors and mechanisms of the location and recognition of conspecific adults, mating choices, mating, and oviposition. The relationship between reproductive and flight behaviors and the rhythm of flight needs further study to explore the infestation regularity of D. citri and provide helpful information to develop integrated pest management strategies. It is expected that the review of reproductive behavior of D. citri will provide reference for scientific research, population monitoring, and comprehensive management of D. citri in China.

Koca, Abdurrahman Sami; Kütük, Halil

doi: 10.1007/s41348-020-00319-9pmid: N/A

Cabbage whitefly, Aleyrodes proletella L. (Hemiptera: Aleyrodidae), causes severe damage to Brassica vegetables. This study was conducted to evaluate the seasonal population dynamics of A. proletella and its parasitoids throughout the 2016 and 2017 growing seasons in Düzce Province in Turkey. To estimate whitefly density and parasitism rates, collard leaf samples infested with whitefly were collected from fields where no pesticides were applied. Collard leaves were cultured for emergence of the adult parasitoids, which were identified as Encarsia tricolor Forster (Hymenoptera: Aphelinidae) based on morphological and molecular characteristics. Seasonal mean densities of A. proletella ranged from 11.20 to 19.30 nymphs/leaf in 2016 and from 15.19 to 86.66 nymphs/leaf in 2017. The highest parasitism rates were 6.46% and 24.79% in 2016 and 2017, respectively. Whitefly nymphs peaked in July and August during both years. The first parasitized whitefly nymphs were observed in July, and maximum parasitism rates occurred in the second half of August during both years. These findings provide significant contributions for studies involving the conservation of parasitism of A. proletella.

Hategekimana, Athanase; Erler, Fedai

doi: 10.1007/s41348-020-00311-3pmid: N/A

Fecundity (egg production) and fertility (egg hatchability/progeny production) are important components of both sexual and asexual reproduction of insects. Some plant essential oils (EOs) are reported to be active inhibitors against various insect pests by reducing or completely hindering their fecundity and fertility. The present study was carried out to determine the inhibitory effects of three plant EOs [eucalyptus (Eucalyptus camaldulensis Dehn.), peppermint (Mentha piperita L.) and anise (Pimpinella anisum L.)] and their major components (1,8-cineole, L-menthol and trans-anethole, respectively) on egg-laying and progeny production of bean weevil, Acanthoscelides obtectus Say (Coleoptera: Bruchidae), which is an economically important pest of common bean, Phaseolus vulgaris L. (Fabaceae), in tropical and subtropical regions. The EOs were extracted by hydro-distillation, and their chemical composition was determined by gas chromatography–mass spectrometry. The oils and components were bio-assayed via fumigation against the pest by exposing newly emerged virgin females and young males to the median lethal concentration (LC50) of each material for 10 h. After the exposure, the surviving individuals were mated in the following combinations; treated females × treated males (TF × TM), untreated females × treated males (UF × TM), treated females × untreated males (TF × UM), untreated females × untreated males (UF × UM). According to the results, the highest fecundity inhibition was observed in TF × TM with 86.05%, 71.9% and 55.72% for anise, eucalyptus and peppermint oils, respectively. In addition, the highest progeny production inhibition was seen in the TF × TM combination with 93.3%, 68.0% and 44.9% after exposing to eucalyptus, anise and peppermint oils, respectively. Overall the results showed that the exposure of newly emerged adults by the median lethal concentration of EOs and their major components negatively affected the egg-laying and progeny production of bean weevil. These results may also pioneer new approaches in insect pest control of stored products.

Broumandnia, Freshteh; Rajabpour, Ali

doi: 10.1007/s41348-020-00324-ypmid: N/A

The entomopathogenic fungi are safe and ecofriendly biocontrol agents which can be applied against stored product pests. In this study, potentials of some Iranian isolates of Lecanicillium lecanii (PAL6, PAL7 and PAL8) and Lecanicillium muscarium to control Tribolium castaneum (AGM5) were investigated under laboratory conditions. For this purpose, the LC50 and LT50 values of each isolates to adults of the beetle were estimated. Results showed that all of the isolates were virulent to the pest. The estimated LC50 values were ranged from 2.8 × 106 to 6.13 × 1022 (conidia/mL). The lowest and the highest LC50 values were estimated for L. lecanii (PAL7) and L. mucarium (isolate AGM5), respectively. The LT50 values varied from 4.99 to 13.65 days. The LT50 values were decreased by increasing conidial concentrations of each isolate. Moreover, at each conidial concentration, the LT50 values for L. lecanii isolate PAL8 were significantly lower than other isolates. Totally, among the isolates, L. lecanii isolate PAL7 (at concentration 107 conidia/mL) is the most promising isolate. The laboratory study is preliminary, and further experiments under field condition are required before any recommendations.

López-Lima, Daniel; Desgarennes, Damaris; Lima-Rivera, Dinorah; Carrión, Gloria

doi: 10.1007/s41348-020-00325-xpmid: N/A

A major problem for potato production worldwide is Globodera rostochiensis. Field control of this nematode is difficult because of the high reproductive rate of this genus and its resistance to biotic and abiotic factors. Biological control of nematodes is an increasingly popular strategy because it is effective and has low environmental impact. In this study, the potential of the nematophagous fungus Metarhizium carneum to mitigate the G. rostochiensis population in the presence of a susceptible potato host without previous management and during two crop cycles was evaluated, which included cultivation of the non-host faba bean followed by a susceptible potato crop. The effect of M. carneum application to the soil allowing the field to remain fallow for 2 years was also evaluated. Although M. carneum reduced the G. rostochiensis population by 33% during one potato crop cycle, the yield did not increase. With the application of M. carneum and a faba bean/potato rotation, the nematode population in the soil was reduced by 81%, with a significant increase in yield. Likewise, the use of the fungal biological control agent and the fallow period resulted in an 87% reduction in the nematode population after 2 years. Additionally, Rhizoctonia solani damage in tubers to which M. carneum was applied was lower than that in non-treated tubers in both experiments. The reduction in the population density of G. rostochiensis without the application of the biological control agent, including in the crop rotation and fallow treatments, was very low in both experiments. The combination of two management strategies, such as the use of biological control and crop rotation or a fallow period, may be a viable approach for the integrated management of G. rostochiensis in areas where high densities of this nematode occur.

Dababat, Abdelfattah; İmren, Mustafa; Pridannikov, Mikhail; Özer, Göksel; Zhapayev, Rauan; Mokrini, Fouad; Otemissova, Ainur; Yerimbetova, Aigerim; Morgounov, Alexey

doi: 10.1007/s41348-020-00306-0pmid: N/A

Plant-parasitic nematodes (PPNs) are considered serious damaging on the global cereals production systems. The current study was conducted to evaluate the incidence of PPNs in the main cereal-growing areas in northern Kazakhstan. PPNs were detected in about 90% of 78 soil samples and thirteen genera were identified, including Pratylenchus, Heterodera, Geocenamus, Ditylenchus, Helicotylenchus, Rotylenchus, Pratylenchoides, and Tylenchorhynchus. Out of the 78 samples, 32 samples were found infested by Heterodera filipjevi based on the morphological and molecular analysis. To our knowledge, this is the first report on this cereal cyst nematode species in northern Kazakhstan. During the morphological and molecular assays, intraspecific polymorphism was observed within H. filipjevi populations and the populations divided into at least two groups. The highest frequency of infestation of H. filipjevi (76%) was recorded from Kokshetau Province when compared to other provinces: Astana (50%), Petropavl (37%), and Kostanay (16%). The highest number of cysts (30.4) was found among Astana samples while the lowest number of cysts (18.2) was recorded from Kostanay samples. Cyst nematodes can maintain their population above the economic threshold as stimulated by the cereal monoculture system (mainly wheat) which is similar to the cereal production systems of northern Kazakhstan.

Petreš, Mladen; Kalajdžić, Jelena; Milić, Biserka; Magazin, Nenad; Stankov, Aleksandra; Vukotić, Jelena; Grahovac, Mila

doi: 10.1007/s41348-020-00302-4pmid: N/A

Hot water treatments of apple fruits prior to long-term storage have a high potential as a physical measure against apple fruit storage rot caused by plant pathogenic fungi. Fusarium species are increasingly found as causal agents of postharvest apple fruit rot. The effect of high temperatures on casual agents of Fusarium fruit rot, F. avenaceum and F. graminearum, was tested in this article. In in vitro assay, spore suspensions of F. avenaceum and F. graminearum were exposed to high temperatures (ranging from 45 to 90 °C) at different duration (ranging from 30 s to 20 min) and the treatments that significantly inhibited mycelial growth of the isolates (53 and 57 °C for 3 and 5 min) were tested in vivo by hot water treatment of inoculated apple fruits of Fuji cultivar. The obtained results showed that the most promising hot water treatment should be between 53 and 57 °C and between 3 and 5 min of the exposure period.

Ren, L.; Wang, S. F.; Shi, X. J.; Cao, J. Y.; Zhou, J. B.; Zhao, X. J.

doi: 10.1007/s41348-020-00316-ypmid: N/A

In 2014, 45 isolates of Colletotrichum spp. from Jinzhong City (Shanxi Province, China) that had never used Qo inhibitor (QoI)-type fungicides were characterised for sensitivity to picoxystrobin through growth inhibition tests with 100 μg/ml salicylhydroxamic acid. The isolates showed similar sensitivity, the EC50 values ranging from 0.021 to 0.197 μg/ml. Baseline sensitivity was distributed as unimodal curves with mean EC50 values of 0.108 ± 0.004 μg/ml for picoxystrobin. In field experiments in 2015 and 2016, 57 isolates of Colletotrichum spp. from four geographical regions of China revealed a mean EC50 value of 1.074 ± 3.287 μg/ml, which was 9.94-fold higher than the baseline sensitivity. In these four regions, Qo inhibitors provided control efficacy of about 85%. The isolates with low, moderate, and high resistance to the QoI fungicide picoxystrobin accounted for 3.5%, 7.0%, and 5.3% of all 57 isolates, respectively. However, during continuous asexual culturing of the resistant isolates on fungicide-free medium for ten generations, picoxystrobin sensitivity of low and moderate resistant isolates was restored. Moreover, spore production, mycelial growth rates, and spore germination rates of the resistant isolates did not differ significantly from those of the sensitive isolates. Genetic analysis for mutations showed that picoxystrobin resistance was associated with a point mutation from GGT to GCT at codon 143 in the CytB gene (G143A) in high resistant mutants of C. gloeosporioides, but no point mutation was detected in low and moderate resistant isolates. Positive cross-resistance between picoxystrobin and QoIs (azoxystrobin and kresoxim-methyl) was observed; no cross-resistance between picoxystrobin and other type fungicides (carbendazim and prochloraz) was detected.

Sahu, Pramod Kumar; Thomas, Pious; Singh, Shailendra; Gupta, Amrita

doi: 10.1007/s41348-020-00320-2pmid: N/A

The study was conducted to comprehend the facets of culturable endophytic diversity correlating with the fitness of cultivar. Tomato bacterial endophytes from cultivars Arka Rakshak (AR; multi-disease tolerant hybrid) and Pusa Ruby (PR; susceptible check) were isolated. Molecular identification quantified that only two genera Rhizobium and Bacillus were common in both cultivars out of fifteen genera isolated. Genera Microbacterium, Enterobacter, Falsibacillus, Cohnella, Youhaiella, and Fluviicola were found only in AR, whereas genera Chryseobacterium, Pseudomonas, Dyadobacter, Staphylococcus, Micrococcus, Microvirga, and Shinella were found only in PR. Although the genera level diversity indicated cultivar specificity, except for firmicutes (7 in AR and 4 in PR), the distribution of taxonomic class alphaproteobacteria, gammaproteobacteria, bacteroidetes, and actinobacteria was almost similar. Gram-positive class was dominated by firmicutes and Gram-negative by alphaproteobacteria in both cultivars. On contrary, the collective functional profile for the production of hydrogen cyanide, ammonia, and siderophore, apart from phosphate solubilization and indole acetic acid production, indicated the dominance of endophytes from AR (multi-disease tolerant hybrid). The pattern of antagonistic ability against 15 different strains of R. solanacearum indicated that endophytes from tolerant cultivar exhibit higher in vitro suppression. The number of antagonists and the extent of inhibition both were higher in AR endophytes. However, the genetic capability for harboring eight antimicrobial compounds producing genes was found to be well distributed in both cultivars. Results showed that the functional aspects of these bacterial endophytes correlate with cultivar fitness more than that of taxonomic and genetic diversity.Graphic abstract[graphic not available: see fulltext]

Erincik, Birsen Geçioğlu

doi: 10.1007/s41348-020-00321-1pmid: N/A

Verticillium dahliae has been recently characterized as a heterothallic fungus having two MAT idiomorphs, MAT1-1 and MAT1-2, which suggested that a putative sexual life cycle of the pathogen might exist. A successful mating in heterothallic fungi requires two individuals of opposite mating types present together in the same site. Co-occurrence of both mating types of V. dahliae has been investigated in many parts of the world but not comprehensively in Turkey. This study aims at determination of the mating types in V. dahliae populations in the major cotton producing districts of Aydın Province. A total of 123 V. dahliae isolates obtained from cotton were subjected to PCR assay with the two pairs of specific primers for mating type determination. All of the isolates produced a single amplicon approximately 600 bp in size, which is known belonging to MAT1-2 idiomorph. The results suggested that MAT1-1 has not been introduced yet to the Aydın Province. Absence of MAT1-1 idiomorph will deprive the pathogen from sexual reproduction and this maintains that the pathogen population remains clonal with presumably having low levels of genetic diversity.