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Seven Gluconacetobacter diazotrophicus strains from sugarcane roots were screened for their efficiency to promote growth and nutrient uptake in sugarcane at three levels of urea N (0, 75, and 150 kg N ha−1). Inoculation by these strains improved germination, tiller number and plant height. N-uptake and apparent N-recovery increased due to inoculation and the effect was more at N75 level. Gluconacetobacter diazotrophicus isolate IS100 was found to be the most efficient in promoting plant growth and nutrient uptake in sugarcane.

Application of environmentally friendly agents to reduce the use of chemicals and to enhance growth of plants is an ultimate goal of sustainable agriculture. The use of plant growth-promoting endophytes has become of great interest as a way to enhance plant growth and additionally protect plants from phytopathogens. In this study, 135 isolates of endophytic bacteria including actinomycetes were isolated from roots of commercial sugarcane plants cultivated in Thailand and were characterized for plant growth-promoting (PGP) traits. Based on morphological and 16S rRNA sequence analysis, the endophytes were distributed into 14 genera of which the most dominant species belong to Bacillus, Enterobacter, Microbispora, and Streptomyces. Two strains of endophytic diazotrophs, Bacillus sp. EN-24 and Enterobacter sp. EN-21; and two strains of actinomycetes, Microbispora sp. GKU 823 and Streptomyces sp. GKU 895, were selected based on their PGP traits including 1-aminocyclopropane-1-decarboxylate deaminase, indole-3-acetic acid, nitrogen fixation, phosphate solubilization, and siderophore production for evaluation of sugarcane growth enhancement by individual and co-inoculation. Sixty days after co-inoculation by endophytic diazotrophs and actinomycetes, the growth parameters of sugarcane plants were significantly greater than that of individual and un-inoculated plants. The results indicated that these endophytes have high potential as PGP agents that could be applied to promote sugarcane growth and could be developed as active added value biofertilizers in the future.

Specific amino acids identified in root exudates promote sugarcane growth by enhancing Klebsiella variicola DX120E colonization and modulating rhizosphere bacterial community

Sodium salicylate and ammonium sulfate were applied to leaf surfaces along with suspensions of the biological control agents Pseudomonas syringae Cit7(pNAH7), which catabolizes salicylate, and Cit7, which does not catabolize salicylate, to determine whether enhanced biological control of bacterial speck of tomato could be achieved. Foliar amendment with salicylate alone significantly enhanced the population size and the efficacy of Cit7(pNAH7), but not of Cit7, on tomato leaves. Application of ammonium sulfate alone did not result in enhanced population size or biological control efficacy of either Cit7(pNAH7) or Cit7; however, when foliar amendments with both sodium salicylate and ammonium sulfate were applied, a trend toward further increases in population size and biological control efficacy of Cit7(pNAH7) was observed. This study demonstrates the potential of using a selective carbon source to improve the efficacy of a bacterial biological control agent in the control of a bacterial plant disease and supports previous conclusions that the growth of P. syringae in the phyllosphere is primarily carbon limited and secondarily nitrogen limited.

The cultivation of Madagascar periwinkle (Catharanthus roseus L.) is affected by many pathogens, including soil-borne pathogenic fungi such as Fusarium spp., Phytophthora spp., and Pythium spp. The importance of biological control methods has been increasing due to the ongoing phase-out of chemical pesticides. Biocontrol agents like Bacillus amyloliquefaciens, Trichoderma asperellum, and T. atroviride are increasingly used due to their pathogen suppression capabilities and ability to enhance plant resilience to stress. This study evaluated the in vitro efficacy of T. asperellum against F. oxysporum. Significant inhibition of F. oxysporum growth was observed in dual culture confrontation test. Our results highlighted the potential of T. asperellum as a biocontrol agent for managing F. oxysporum in C. roseus cultivation. The application of these agents can reduce the dominance of chemical pesticides and promote sustainable agriculture practices.

In the past decade pyrethroids have emerged as a major class of highly active insecticides due to their high bio-efficacy and relatively low toxicity in comparison to organochlorine and organophosphate pesticides, which are more acutely toxic to birds and mammals than the pyrethroids. These chemicals have been largely used for the control agricultural pests, with Lepidoptera representing the highest percentage (40%) of pyrethroid targeted insects, followed by sucking insects and Coleoptera (Wirtz et al., 2009). On the other hand, insect parasitoids are of high importance in natural and agricultural ecosystems where they regulate or influence the population density of their hosts, being therefore worldwide used in the control of several agricultural pests, particularly Lepidoptera and Hemiptera. Parasitoids can be released in the field either by inundative (for an immediate and non sustaining reduction of the target host population) or inoculative (where the objective is to release the natural enemies early in the season and so is the progeny who will have a later effect on the target host population) approaches. In the first approach, parasitoids are positioned as a fast-acting replacement of insecticides, while in the second parasitoids are considered as one aspect of integrated pest management (Smith, 1996). According to the review by Collier and Steenwyk (2004), biological control by augmentative releases of natural enemies is not likely to replace insecticides in the near future, in part due to the apparent lack of efficacy compared to conventional insecticide applications. Thus the integration of biological and chemical controls is an essential alternative to the conventional use of insecticides that requires knowledge of the lethal and sublethal effects that chemicals may have on the natural enemies. Actually most of the studies regarding the effects of insecticides (inclusive for pyrethroids) on parasitoids and other natural enemies have relied on the evaluation of acute toxicity by determination of a median lethal dose (LD50) or concentration (LC50) (Desneux et al., 2007). Though estimation of LD50 or LC50 is a simple and a fast approach to compare and evaluate the acute toxicity of insecticides to parasitoids, it overlooks sublethal effects that will interfere with the physiology and behaviour of the natural enemies. Insecticides may directly interfere with the efficacy of biological control

The important invasive thrips species Hawaiian flower thrips, Thrips hawaiiensis (Morgan, 1913) (Thysanoptera: Thripidae) was first reported in Türkiye in 2015. Since then, it has been causing damage in lemon orchards. This study was conducted to reveal the most effective insecticides, the most effective spraying time and the efficacy of biological control. For this purpose, the effectiveness of five insecticides (480 g/l spinosad, 25% spinetoram, 100 g/l spirotetramat, 50% flonicamid, 240 g/l tau-fluvalinate), effect of three spray programs and effectiveness of predatory bug Orius laevigatus (Fieber, 1860) (Hemiptera: Anthocoridae) were tested in a lemon orchard [Citrus limon (L.) (Rutales: Rutaceae)] in Erdemli district of Mersin province in 2018 and 2019. In order to determine the most effective spraying time, three spray programs were tested. In Program 1, two sprays during the flowering period were applied. In Program 2, two sprays were applied, one at petal fall and the other at the small fruiting stage. In Program 3, one spray at petal fall and two sprays in the fruiting stages were applied. According to the results, 240 g/l tau-fluvalinate and 50% flonicamid showed the lowest efficacy of the insecticides in the three programs. Spinetoram was found the most effective of the others. Insecticide applications to control T. hawaiiensis during the flowering period (Program 1) had low efficacy. Program 3 was found to be the most effective. Predatory bug O. laevigatus, as a biological control agent was found to have a potential efficacy for suppressing T. hawaiiensis populations.

Soil fertility regulates invasive herbivore performance and top-down control in tropical agroecosystems of Southeast Asia

Introduction: Biological control often relies on the simultaneous use of several biocontrol agents (e.g. parasitoids and generalist predators) on shared or separate prey, and direct and indirect interactions may reduce overall efficacy of biological control. Additionally, biological control based on omnivorous predators might be influenced by plant-provided food sources. Therefore, identification of such trophic links is of primary importance to the success of biological control programs. How populations interact in a multi-food sources and multi-predators agro-ecosystems is one of the fundamental questions in ecology, and is crucial to the current efforts to increase agroecosystem biodiversity. Methods: I present a summary of research activities aiming at identifying direct and indirect interaction patterns that underpin invasive pest biological control efficiency. Cage experiments in greenhouses (mesocosms) allowed recording population dynamics in different associations of pest and natural enemy species, and laboratory experiments (microcosms) allowed understanding precisely the behaviors and mechanisms at play. The studies focus on the biological control of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), the invasive tomato leafminer. Results/Conclusion: Results outlined a major role of indirect interactions on population dynamics and unexpected interactions between species, such as kleptoparasitism. We observed that the highest diversity provides the best control when using biological control agents. (Texte integral)

The surface hydrophobicity, viability and biocontrol ability of Penicillium oxalicum spores, produced either in aerial or submerged culture, were characterized. A phase distribution test showed that spores produced in both methods of culture were highly hydrophobic, but those produced in aerial culture were more hydrophobic. Spores stored fresh at either 4 or 25 degrees C retained a high viability (80%) after 27 weeks of storage, although aerial spores survived better. Freeze-drying severely affected viability, especially of submerged spores. Biocontrol ability against Fusarium oxysporum f. sp. lycopersici was studied in the growth chamber. Aerially- produced spores were more effective than submerged ones. Aerially-produced P. oxalicum spores appeared to have more advantages than those produced by submerged culture, in relation to both viability and efficacy. These results demonstrate that physiological changes occur depending on production conditions which significantly influences quality of the biocontrol agent.

نماتدهای ریشه گرهی (Meloidogyne spp) از جمله عوامل بیماریزای بسیار مهمی هستند که خسارت زیادی به محصولات کشاورزی وارد می‌سازند. روش‌های متعددی (تناوب زراعی، ارقام مقاوم و ترکیبات شیمیایی) برای کنترل آنها به کار گرفته شده است. هزینه بالا و مشکلات زیست‌محیطی (ترکیبات شیمیایی)، توجه محققان را به استفاده از روش های غیر‌شیمیایی همچون استفاده از گیاهان و فرآورده های گیاهی برای مدیریت این نماتدها معطوف کرده است. جهت بررسی تأثیر حضور تعدادی از گیاهان خانواده نعناع روی نماتد ریشه‌گرهی، از سه گیاه دارویی آویشن باغی (Thymus vulgaris)، مرزه (Saturea hortensis) و زوفا (Hyssopus officinalis) استفاده شد. این آزمایش در گلخانه ای بصورت فاکتوریل و در قالب طرح کاملا تصادفی با چهار تکرار با کشت تنها و مخلوط گوجه‌فرنگی با گیاهان دارویی زوفا، آویشن و مرزه، در حضور و بدون حضور نماتد انجام شد. ارزیابی نتایج سه ماه بعد از تلقیح نماتد و بر اساس شاخص های رشدی گوجه فرنگی و پارامترهای بیماری زایی نماتد صورت گرفت. تجزیه و تحلیل آماری داده های حاصل ‌‌نشان دهنده اثر معنی‌دار حضور سه گیاه دارویی مذکور روی کاهش خسارت نماتد بود. مؤثرترین گیاه در کاهش خسارت و بیماری زایی نماتد مرزه بود و آویشن باغی، و زوفا در درجات بعدی قرار گرفتند. در مجموع بررسی‌های گلخانه‌ای گیاهان دارویی مورد آزمایش، اثرات کنترلی مطلوبی علیه نماتد ریشه گرهی از خود نشان دادند و می‌توان استفاده از آنها را در برنامه‌های مدیریت نماتد ریشه‌گرهی مورد توجه قرار داد.

Integrated control of Meloidogyne incognita in tomatoes using fluopyram and Purpureocillium lilacinum strain 251

The sedentary root-knot nematodes, Meloidogyne spp., and the migratory root-lesion nematodes, Pratylenchus spp., cause significant yield losses, particularly in aerobic and upland rice production systems. Recently, the Asian rice Oryza sativa accessions LD 24 and Khao Pahk Maw (KPM) were shown to be highly resistant to M. graminicola. In this study, we have analyzed the responses and broadness of resistance of these two rice genotypes to another root-knot nematode M. javanica and a root-lesion nematode P. zeae. The penetration as well as post-penetration development and reproduction of nematodes were compared including known susceptible and resistant genotypes. Our results indicate that the genotype KPM confers strong resistance to both M. javanica and P. zeae, while LD 24 was resistant to M. javanica and susceptible to P. zeae. Detailed observations revealed that similar numbers of M. javanica or P. zeae penetrated the resistant and susceptible hosts during early infection stages. However, the development and reproduction of both nematodes were arrested or reduced in resistant genotypes, implying that resistance occurs at the post-penetration stage.

ABSTRACTStriga presents a major threat to cereal crop production in sub-Saharan Africa. A combined use of host resistance and biological control agents holds promise as a key strategy for sustainable, integrated Striga management in maize (Zea mays L.) production. The objective of this study was to determine resistance against Striga asiatica (L.) Kuntze and compatibility of selected maize genotypes to a biocontrol agent, Fusarium oxysporum f.sp. strigae (FOS), for integrated Striga management. Eighteen maize genotypes were evaluated under glasshouse and field conditions using three treatments: 1) maize genotypes sown without Striga infestation and FOS treatment (control), 2) maize genotypes grown under Striga infestation and; 3) FOS-treated maize genotypes grown under Striga infestation. The results showed that genotype-by-FOS interaction significantly (P < 0.05) affected all traits, except anthesis-to-silking interval, ear aspect score and Striga emergence count at 8 weeks after planting. All maize and Striga traits were significantly affected by FOS treatment (P < 0.001), although the efficacy of FOS seemed to be maize genotype dependent. Mean grain yield was 4.2 t ha−1 for the control, 2.63 t ha−1 for the FOS-treated and 2.17 t ha−1 for the untreated genotypes. Overall, the combined effect of host resistance and inoculation of seed with FOS reduced parasitic infestations and Striga damage symptoms, resulting in improved agronomic performance. Five genotypes (ZM1523, ZM 1423, ZM 1421, NC QPM and Colorado) showed resistance to S. asiatica and compatibility to FOS. The study demonstrated the efficacy of host resistance and biological control in integrated management of S. asiatica in maize.

Spodoptera frugiperda J.E. Smith (Spodoptera: Noctuidae) is an invasive pests of maize that has been reported around the world. Control efforts using biological agents continue to be developed, including the use of entomopathogen bacteria such as Bacillus thuringiensis. To boost the efficacy and efficiency of biological control, formulations are required. The objective of this study was to develop biopesticide formulations and evaluate their efficacy. The research was carried out by formulating B. thuringiensis strain BtJ2 (1010 cfu mL -1) in liquid and paste formulations. The effectiveness of the formulations was evaluated using the feed dipping method. The results showed that paste formulations at a concentration of 10% caused 100% mortality, whereas the liquid formulation resulted in 85% mortality. The LC90 for the paste formulation was 6.66%, while the LC90 for the liquid formulation was 12.90%. Both the liquid and paste formulations had similar effects on mortality and viability. Based on the LC90 and LT90, the paste formulation was more efficient and faster in killing S. frugiperda than the liquid formulation. The results of this study provide recommendations that B. thuringiensis as a bioinsecticide is better formulated in a paste than in a liquid form.