Phytoparasitica最新文献

Spider mites are important pests of cotton, a vital fiber crop cultivated in sun-drenched regions. This study investigated the prevalence and distribution of spider mite species infesting cotton fields in Aydin province, Türkiye. Spider mites were found in a significant portion (89%) of the surveyed fields. The two most abundant mite species, were the red form (RF) of Tetranychus urticae (57.1%) and T. turkestani (39.3%). A minor presence of T. urticae green form (GF) (3.6%) was observed. Tetranychus urticae RF was more prevalent in coastal areas, while T. turkestani was more common inland. Field surveys demonstrated that areas with higher T. urticae RF prevalence exhibited more frequent spraying, potentially due to this species’ greater capacity to develop resistance compared to T. turkestani. This study also investigated the prevalence of Wolbachia, Rickettsia, Cardinium and Spiroplasma endosymbionts, which are linked with pesticide resistance due to their ability to degrade pesticides, in these mite populations. The study confirmed the presence of Wolbachia and Rickettsia endosymbionts in spider mite populations in Türkiye. However, no Cardinium or Spiroplasma were detected in any of the populations. Infection rates of the detected endosymbionts differed between T. urticae and T. turkestani. Future studies should investigate the resistance levels of these tetranychid mite species as well as the role of their endosymbiotic bacteria in resistance in cotton-growing areas.

The present investigation was carried out to study the leaf composition and methylglyoxal pathway in four barley genotypes on infection with Bipolaris sorokiniana. PL 891 was found to be highly resistant, followed by PL 807 as a resistant cultivar, while PL 426 and RD 2786 depicted susceptible behavior to spot blotch disease. Total soluble sugars increased by more than 1.4 folds in resistant genotypes at the growth stage (GS) 55 (half inflorescence emerged) while declined in the sensitive ones. However, control leaves of the latter had more total soluble sugars and cholorophyll contents at GS 55 but declined after infection. Glyoxalase I activity increased in the lower leaves of PL 807, PL 891 and PL 426 on infection with Bipolaris sorokiniana at GS 87 (hard dough). Glyoxalase II activity increased in the infected leaves of PL 891, PL 807, and PL 426 by 1.3, 1.1 and 1.4 folds respectively at GS 55 stage while declined by more than 1.3 folds in the susceptible genotype RD 2786. Glyoxalase III activity increased in the flag and lower leaves of PL 807 at both stages while declined or remained unaffected in other genotypes indicating the action of glutathione independent pathway in this genotype. Methylglyoxal reductase activity increased by more than 1.3 and 1.9 folds respectively in the flag and lower leaves of both the resistant genotypes. Negative correlation of MG with Gly I (-0.431**) and with methylglyoxal reductase (-0.274*) verified the role of these enzymes in its detoxification in response to leaf blight disease. Analysis of the data shows that the rise in total soluble sugars at initial stages and the activities of Gly III and methylglyoxal reductase at later stages along with the maintenance of redox pool could be responsible for the resistant nature of PL 891 and PL 807.

Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) is a predator of phytophagous pests in crops; however, this natural enemy may be exposed to chemical insecticides. Thiamethoxam (neonicotinoid) and chlorantraniliprole (anthranilic diamide) are classified as selective insecticides, but their side effects on the midgut of non-target organisms are poorly understood. This study aimed to assess the toxicity and side effects of thiamethoxam and chlorantraniliprole on the midgut of C. externa larvae and adults. Chrysoperla externa larvae and adults were fed eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and a honey solution, respectively, both containing the insecticides. Mortality rates were evaluated. Histopathological examination of the midgut was conducted on larvae and adults exposed to the calculated LC₅₀ at one, 12, and 30 days after exposure. The results showed that both insecticides did not induce histopathological or cytotoxic effects on the midgut cells of C. externa larvae and adults. These findings suggest that thiamethoxam and chlorantraniliprole, in low concentrations, have potential to be utilized in integrated pest management strategies involving this natural enemy.

Gymnema sylvestre (Retz.) R. Br. ex Sm is a vital medicinal plant effective in treatment of Diabetes mellitus. The soft scale, Megapulvinaria maxima (Green) (Hemiptera: Coccidae), has emerged as a significant pest infesting Gymnema sylvestre in the semi-arid region of India. A random survey revealed infestation on leaves, stems, and fruits, by both nymphs and adults extracting plant sap and secreting excess honeydew. This honeydew adversely impacts leaf quality which is essential for bio-molecule extraction. Early pest detection is crucial for effective management, but the precise morphological identification of scale insects poses challenges. Utilizing morphological keys and sequencing the Cytochrome c oxidase subunit I (COI) gene (GenBank No. OR602704), we identified the scale insects as M. maxima. Evolutionary divergence studies and phylogenetic analysis indicated no divergence with the Republic of Korea isolate (MK543913), while with the isolate of the accession number, MW450949 highest evolutionary divergence was exhibited (0.72%). The isolates (KP189890) and (KP189893) from China showed less association with the study isolate compared to other populations. The severity of incidence peaked during the 48th and 45th standard meteorological weeks (SMW) in 2019–20 and 2020–21, reaching severity levels of 3.67 and 3.56, respectively. In both years, morning relative humidity showed a significantly positive correlation (r = 0.152 and 0.364*). These findings offer valuable insights for early pest detection and formulating effective management strategies. To the best of our knowledge, this is the first comprehensive study of M. maxima affecting the medicinal herb G. sylvestre in India and globally.

Diaspis echinocacti (Bouché), a globally distributed cochineal scale insect, poses a significant threat to Opuntia spp. in Morocco and worldwide. This study explores the ecological dynamics of D. echinocacti across different Opuntia spp. varieties, employing antixenosis and antibiosis tests in a controlled greenhouse environment (25.3 ºC). In the antixenosis test, Opuntia spp. varieties displayed varying levels of resistance at 6–24 h post-infestation. Marjana and Belara exhibited early resistance with significantly lower numbers of insects (6 h: 4.4, 9.8; 12 h: 3.2, 5.1; 24 h: 2.3, 4.4), while Aakria, Ghalia, and Karama sustained higher susceptibility (6 h: 71.3, 82.1, 85.6; 12 h: 75.2, 89.6, 105.6; 24 h: 105.6, 110.3, 118.0). In the antibiosis test, the life cycle, behavior, and reproductive parameters of D. echinocacti were assessed. Marjana and Belara exhibited longer early nymphal stages compared to Aakria, Ghalia, and Karama. Longevity in both females and males was highest in Ghalia and Karama, while Marjana and Belara showed the shortest duration. Female life cycles ranged from 63.4 to 88.2 days, with Marjana and Belara having the shortest durations and Karama the longest. Fecundity was highest in Karama (152.80 eggs) and lowest in Marjana (12.60 eggs). Population growth parameters highlighted that Karama (r = 0.09, λ = 1.10, R₀ = 61.73) and Ghalia (r = 0.09, λ = 1.09, R₀ = 56.54) exhibited the highest intrinsic rate of increase, finite rate of increase, and total reproduction per generation. This study offers essential insights into D. echinocacti dynamics, informing pest management and advancing our understanding of ecological interactions in cactus ecosystems, particularly for breeding programs targeting Opuntia spp. resistance to scale insects.

The proliferation of weeds in agricultural fields competes directly with crops for essential resources such as, leading to reduced crop yields and economic profitability. The objective of this study was to evaluate the effect of weed management practices on dry bean productivity and economic profitability. Field experiments were conducted between 2018 and 2019 following a Randomized Complete Block Design with four replications and seven treatments. The treatments included: MW (Manual hoe weeding 21DAS), H1 (paraquat 3 l ha⁻¹), H2 (acetochlor 3 l ha⁻¹), H3 (atrazine 3 l ha⁻¹), H1H2 (paraquat 1.5 l ha⁻¹plus acetochlor 1.5 l ha⁻¹), H1H3 (paraquat 1.5 l ha⁻¹ plus atrazine 1.5 l ha⁻¹) and H2H3 (atrazine 1.5 l ha⁻¹ plus acetochlor 1.5 l ha⁻¹). Dry seed yield obtained in 2018 were similar regardless of treatments. However, in 2019, among the herbicides, H1 induced the highest yield (1t ha⁻¹), while the lowest (0.45 t ha⁻¹) was recorded with H2. In addition, the decrease in yield under MW (0.86 t ha⁻¹) was due to the high density of following species: Cynodon dactylon, Commelina benghalensis, Imperata cylindrica, Bidens pilosa, Euphorbia heterophylla and Euphorbia hirta. The economic analysis of treatments using the Ratio Cost Value (RVC > 1) classified them in descending order: MW > H1 > H2H3 > H3 > H1H3 > H2 > H1H2. However, when the cultivated area to be weeded is expanding and labor becomes scarce, the rains are regular and abundant, manual hoeing may become tedious. In this case, the application of 3 l ha⁻¹ of paraquat becomes an alternative to manual hoeing for farmers wishing to increase dry bean seed production.

The stability of host plant resistance to insects, and efficacy of insecticides against the insect pests is influenced by several inherent traits of the target insects in addition to the environmental factors. Spotted stem borer, Chilo partellus (Swinhoe) is a key pest of maize and sorghum. It undergoes both hibernation and aestivation depending upon the prevailing climatic conditions. We studied the host preference and damage potential of this pest in maize and sorghum, and its susceptibility to different insecticides in F₁ progenies of hibernating, aestivating and nondiapausing strains of C. partellus. The larvae from hibernating strain resulted in greater leaf damage and deadhearts, and had greater larval weight and better survival on maize and sorghum than those from the aestivating and nondiapausing strains, although there were a few exceptions. The susceptible maize and sorghum genotypes were highly preferred by the hibernating larvae, while the resistant genotypes were preferred most by the aestivating strain. Maize was least preferred, while sorghum was most preferred by the larvae from hibernating as compared to aestivating and nondiapausing strains of C. partellus. The larvae from aestivating strain were least susceptible to cypermethrin and thiamethoxam, but highly susceptible to deltamethrin and imidacloprid as compared to the other strains. The present studies showed significant differences in preference and damage potential in the host crops, and susceptibility to insecticides in diapausing and nondiapausing strains of C. partellus. Identification of stem borer resistant genotypes of sorghum and maize, and the insecticides with stable efficacy will be useful for integrated management of this pest.

The Sunn pest, Eurygaster integriceps Puton (Heteroptera: Scutelleridae), is one of the most important pests of wheat crops in Iran and the Middle East. Chemical control by high-volume spraying is the most common method of controlling this pest. The current ground sprayers lack advanced spraying technologies, which results in low efficiency. This study aimed to investigate the efficacy of using an Unmanned Aerial Vehicle (UAV) sprayer for the chemical control of wheat Sunn pest. The effectiveness, field capacity, and costs of chemical insecticide application were compared between the UAV sprayer and the Very Low Volume (VLV) Knapsack Sprayer (KS). We found that the chemical control effectiveness of the two spraying methods was not significantly different. The UAV sprayer and the VLV knapsack sprayer had an effectiveness percentage of more than 95%. The UAV sprayer was better than the other in terms of field capacity, insecticide dosage ml ha-1, spray volume L ha-1, reduced drift, and the probability of the operator exposure. The field capacities of the UAV sprayer and the VLV knapsack sprayer were 3.75 and 0.5 hectares per hour, respectively, and the spray volumes were 14.6 and 30.0 L ha-1, respectively.5.5 and 0.8 hectares per hour, respectively, and the spray volume was 14.6 and 30.0 L ha⁻¹, respectively.

Phytoseiid predatory mite, Neoseiulus longispinosus (Evans), is employed to control various pest species, such as phytophagous mites and arthropods. Depending on the host plant, the effectiveness of predators against the target pest may change. However, comparative studies on the life history and predation potential of N. longispinosus on different vegetable hosts have not yet been conducted. Therefore, in the present study, experiments were conducted to determine the indirect effect of several host plants on the biology, predation rate and demographic parameters of N. longispinosus against Tetranychus urticae. The results showed that female longevity was maximum on bean (25.40 days) and minimum on brinjal and tomato (14.22 days each). On bean, the female predatory mite consumed the highest prey (139.50 eggs) during its entire lifespan. The demographic parameters were analyzed and the results were better on bean and followed by cucumber, while they were comparatively poor on brinjal and tomato. These results highlight how crucial host plants are for the effectiveness of biological control. Nevertheless, further studies are required to investigate in detail the role of plant biophysical characters on the predation and demographics of the predator.

To investigate the morphological factors contributing to resistance to yellow mite, Polyphagotarsonemus latus and thrips, Scirtothrips dorsalis in chilli, an analysis was conducted on 15 chilli genotypes, examining various traitsviz. trichome density, length, and angle, along with leaf thickness, length, breadth, and area. Among the genotypes, SL-696 exhibited the highest trichome density (87.67/0.75mm²), while IS-267 displayed the lowest density (19/0.75mm²), and C-142 lacked trichomes altogether. In terms of trichome length, SR-4611 had the maximum (5.02 µm), contrasting with PUP-661, which had the minimum length (1.16 µm). PCH-757 featured the highest trichome angle (44.47°), while AC-105° showed the lowest angle. C-142 demonstrated the greatest leaf thickness (264.67 µm), whereas SL-466 exhibited the smallest thickness (79.60 µm). PUP-661 displayed the highest values for leaf length (9.10 cm), breadth (3.93 cm), and area (148.19 cm²), with PP-418 exhibiting the minimum values for length (3.87 cm), breadth (1.40 cm), and leaf area (44.03 cm²). Analyses of correlations between damage score/LCI and various morphological leaf traits indicated weak, negative, yet nonsignificant associations with trichome density, length, angle, and leaf thickness. Conversely, leaf area demonstrated a weak positive but nonsignificant correlation with the damage score.