Biological Control Products Research Articles

A Review of Biological Control One Decade After the Sorghum Aphid (Melanaphis sorghi) Outbreak.

Melanaphis sorghi is a pest that is native to Africa but is now distributed worldwide. In 2013, its destructive capacity was demonstrated when it devastated sorghum crops in the United States and Mexico, making it a new pest of economic importance in North America. At the time, the phytosanitary authorities of both countries recommended the use of pesticides to control the outbreak, and biological control products for the management of this pest were not known. In response to the outbreak of M. sorghi in North America, several field studies have been performed in the last decade on sorghum crops in the USA and Mexico. Works have focused on assessing resistant sorghum hybrids, pesticide use, and recruitment of associated aphid predators and entomopathogens for natural control of M. sorghi populations. The objective of this review is to compile the information that has been generated in the past decade about indigenous enemies affecting M. sorghi naturally in the field, as well as the search for biological control alternatives and evaluations of interactive effects of resistant sorghum hybrids, pesticides, and natural enemies. To date, different predators, parasitoids, fungi, and bacteria have been evaluated and in many cases found to affect M. sorghi populations in sorghum agroecosystems or laboratory bioassays, and the use of resistant sorghum varieties and pesticides did not have clear toxic effects on natural enemy populations. Many of the macroorganisms and microorganisms that have been evaluated as potential biological controls have shown potential as alternatives to synthetic pesticides for keeping M. sorghi population densities below economic damage thresholds and are compatible with integrated management of sorghum aphids. While most tests of these biological alternatives have shown that they have aphidicidal potential against sorghum aphids, it is crucial to take into account that their effectiveness in the field depends on a number of abiotic and biotic factors, including soil texture, temperature, humidity, and natural enemies.

Analysis of the Impact of Innovation Subsidy Policy on Biological Enterprises

BASF, one of the world's leading chemical enterprises, has been actively engaged in biotechnology in recent years, committed to integrating biotechnology with traditional chemical technology and promoting the development of sustainable solutions. This report aims to analyze BASF's financial statements for 2021, 2022, and others to evaluate the performance of its biotechnology business in four key aspects: solvency, upstream and downstream competition, profitability, and operating capacity, to provide a reference for corporate decision-makers and investors. According to the public information, BASF is financially stable, and its ROCE has increased significantly, reaching 13.5% in 2021, far higher than the cost of capital, which shows the company's strong profitability and good solvency. BASF's biotechnology business has performed well in profitability. The bio-solution business contributes more than 150 million euros in annual sales and continues to grow. BASF's biological control products, seeds and traits business have been registered or are being registered in many countries, showing strong market potential and profitability. BASF also performed well in the operational capability of biotechnology business. The company has established lean corporate headquarters and global business service department to provide efficient and demand-oriented internal services. With the intensification of market competition and the continuous progress of technology, BASF needs to continue to increase R&D investment, expand market share, optimize supply chain management and improve operational efficiency in order to maintain its leading position and achieve sustainable development.

Functional Characterization of an Odorant Receptor Expressed in Newly Hatched Larvae of Fall Armyworm Spodoptera frugiperda.

In the past decade, Spodoptera frugiperda has emerged as a significant invasive pest globally, posing a serious threat to agriculture due to its broad diet, migratory behavior, and ability to cause extensive plant damage. While extensive research has focused on the olfactory capabilities of adult S. frugiperda, understanding of the olfactory process in larvae remains limited, despite larvae playing a crucial role in crop damage. To address this gap, we identified an odorant receptor (OR), SfruOR40, expressed in the first-instar larvae through phylogenetic analysis. Using quantitative real-time PCR, we compared SfruOR40 expression levels in larvae and adults. We then characterized the function of SfruOR40 against 67 compounds using the Xenopus oocyte expression system and found that SfruOR40 responded to three plant volatiles. Further, behavioral experiments revealed a larval attraction to (-)-trans-Caryophyllene oxide. This study elucidates SfruOR40's role in the olfactory recognition of newly hatched S. frugiperda larvae, expanding our knowledge of such mechanisms in Noctuid moths. Furthermore, it highlights the potential of plant-derived natural products for biological pest control from a behavioral ecology perspective.

Exposure of Beauveria bassiana from different sites to changes in behaviour and mortality of oil palm beetle larvae: Oryctes rhinoceros

The potential of Beauveria bassiana as a biological control agent for Oryctes rhinoceros is still rarely reported. The objective of the research was to analyse the behaviour and mortality of O. rhinoceros larva due to exposure to several of B. bassiana. The research method used the Completely Randomized Design and analysis with 5% Tukey’s test. The results showed that B. bassiana form different sites had the potential to be developed as an effective biological control product in controlling O. rhinoceros as a part of novelty to explore the biodiversity of native biological control in Indonesia. Larvae of O. rhinoceros that were exposed to and infected with B. bassiana experienced changes in movement activity and decreased appetite as well as differences in cuticle colour, the initially limp body will turn stiff while the cuticle colour will change and the next symptom will be white mycelium growth which was proven by the SEM. The B. bassiana from Jember 1 had the highest mortality rate of 37.5% at 30 days after application even though it had the lowest spore density. These results indicate something new and require further study regarding the toxin content of each B. bassiana from different sites.

Monitoring the Photorhabdus spp. bacterial load in Heterorhabditis bacteriophora dauer juveniles over different storage times and temperatures: A molecular approach

Biological control products based on the entomopathogenic nematode Heterorhabditis bacteriophora can vary in virulence (quality). The influence of their symbiotic bacteria Photorhabdus spp. inside the infective dauer juvenile (DJ) on DJ quality has not received much attention in the past. The presence of the bacteria in the DJ is crucial for its biocontrol potential. This investigation provides a method to quantify the bacterial load inside the DJ based on a qPCR technique. Information from the genome of Photorhabdus laumondii strain DE2 was used to identify single copy genes with no homology to any other bacterial accessions. One gene (hereby named CG2) was selected for primers design and for further qPCR experiments. Cross-amplification tests with P. thracensis and P. kayaii, also symbionts of H. bacteriophora, were positive, whereas no amplicons were produced for P. temperata or Xenorhabdus nematophila. We tested our qPCR system in DJ populations carrying defined proportions of bacteria-free (axenic) vs bacteria-carrying nematodes. With an increasing proportion of axenic DJ in a population, virulence declined, and the virulence was proportional to the amount of bacterial DNA detected in the population by qPCR. Along liquid storage over long time, virulence also decreased, and this factor correlated with the reduction of bacterial DNA on the respective DJ population. We observed that stored DJ kept virulent up to 90 days and thereafter the virulence as well as the amount of bacterial DNA drastically decreased. Storage temperature also influenced the bacterial survival. Inside formulated DJ, the loss of bacterial DNA on the DJ population was accelerated under storage temperatures below 7.5 °C, suggesting that reproduction of the bacterial cells takes place when growth temperature is favorable. The role of bacterial survival inside stored DJ can now be adequately addressed using this molecular quality-control technique.

The development of foliar fungal communities of nursery-grown Pinus sylvestris seedlings

ABSTRACT In forest nurseries, foliar fungi play a key role in the health of tree seedlings. The aim of this study was to study the diversity and the development of foliar fungal species associated with nursery-grown Pinus sylvestris, and to evaluate the effect of two biological control products and two growth-stimulating products on seedling growth and disease control, as well as seedling associated fungal community. The study was conducted at four Swedish forest nurseries. Fungal communities were assessed from non-symptomatic needles using high-throughput sequencing of the ITS2 rRNA region. The fungal pathogens Cladosporium sp. (15.1%), Phoma herbarum (14.5%), and Alternaria alternata (5.5%) were among the most abundant fungi. Results showed that the nurseries and the development of fungal communities influenced the occurrence of dominant fungal taxa. Disease prevalence was low and microbial treatments had no significant impact on seedling growth and survival, nor on the number of fungal operational taxonomic units (OTUs), species diversity, and species evenness (p > 0.05). In conclusion, the results showed a dynamic change in foliar fungal community structure over the growing season. With appropriate nursery management strategies and under suitable climatic conditions, nursery seedlings can remain healthy even in the presence of fungal pathogens.

Influencia de la variación de nutrientes en la alimentación sobre la acumulación de AbrB, esporulación y expresión de cry1Ac durante cultivos por lote alimentado de Bacillus thuringiensis

The biological control agent Bacillus thuringiensis (Bt) coordinates metabolic and gene regulation functions to enter to the differentiation process for the synthesis of spores and Cry toxin proteins. The master regulator for sporulation initiation is Spo0A, while AbrB regulator coordinate cellular functions during vegetative and transition growth. To understand how differentiation is modified during fed-batch cultures (FBC) of Bt under variable nutrient conditions, we conducted fermentations with two different nutrient concentration and feeding times using an industrial medium. Since sporulation efficiency has been lower in FBCs than in batch cultures, AbrB was monitored by Western blot during these cultures. Kinetic parameters were used to stablish timing of cell differentiation process, and fermentations were monitored on-line using impedance spectroscopy. AbrB was accumulated during the entire fed-batch culture, when a medium with the highest concentration of carbon and nitrogen sources (FBC1) were fed. Under these conditions, sporulation efficiency and cry1Ac expression were negatively affected, compared to the wild-type strain. Conversely, when the feeding concentration was only half of FBC1, AbrB accumulates in minor proportion, and sporulation efficiency and cry1Ac expression increased (FBC2). These results suggest that variable nutrient conditions can cause an imbalance in the accumulation of transition state regulators such as AbrB during FBCs, which can be detrimental to produce spores and Cry proteins, that are the main Bt products for biological control of agricultural pests.

Precision application of the entomopathogenic nematode Heterorhabditis bacteriophora as a biological control agent through the Nemabot

One of the most important development trends of robots in agriculture is to enable highly precise applications that minimize amounts of chemical components that are harmful to the environment. Precision agriculture is fundamental and inevitable worldwide because it provides more yield to an increasing population, while at the same time reducing inputs. The purpose of this study was to apply entomopathogenic nematodes, which are insect parasites used as biological control agents, through Nemabot. A robotic system that can move in the X-Y-Z coordinate plane has an agitating mechanism for suspension based on water and entomopathogenic nematodes and can perform precise dosing with a peristaltic pump designed and produced as a prototype. The experimental results of the robot application on the exact point, volume, amount, and uniformity of dosing show that the proposed method can effectively solve the problem of applying entomopathogenic nematodes, which are economically more expensive than pesticides. The main contribution of this paper is the proposal of a method to solve the problem of applying the agents precisely. This is the first experiment in which biological control products were applied using a robotic system. A patent application (PCT/TR2019/050768) was made, and the patentability claims were approved and officially registered (TR2018 14310B).

Una cepa de Trichoderma brevicompactum aislada en México reprime el crecimiento de hongos fitopatógenos

Fungi of the Trichoderma genus have been widely studied for their mycoparasitic characteristics that allow the generation of biological control products. In addition, some of them promote plant growth. Currently, there are over 300 species divided into 8 clades or lineages. Despite such diversity, few species have been reported in Mexico, and there is not representativeness of every clade. Here, we present the identification of the 2IG2102 strain of T. brevicompactum based on analysis of 3 phylogenetic markers, as well as its characterization as antagonist towards 2 Fusarium fungi, and it also boosts tomato and cucumber seed germination. Trichothecene biosynthesis might be a mechanism required to inhibit phytopathogens growth and in parallel affect the post-germinative growth of tomato. This is the first report of a Trichoderma belonging to the clade 6 isolated in Mexico, that displays capacity to antagonize fungi and it might produce trichothecenes for biological control.

Multifaceted Impacts of Plant-Beneficial Pseudomonas spp. in Managing Various Plant Diseases and Crop Yield Improvement.

The modern agricultural system has issues with the reduction of agricultural productivity due to a wide range of abiotic and biotic stresses. It is also expected that in the future the entire world population may rapidly increase and will surely demand more food. Farmers now utilize a massive quantity of synthetic fertilizers and pesticides for disease management and to increase food production. These synthetic fertilizers badly affect the environment, the texture of the soil, plant productivity, and human health. However, agricultural safety and sustainability depend on an ecofriendly and inexpensive biological application. In contrast to synthetic fertilizers, soil inoculation with plant-growth-promoting rhizobacteria (PGPR) is one of the excellent alternative options. In this regard, we focused on the best PGPR genera, Pseudomonas, which exists in the rhizosphere as well as inside the plant's body and plays a role in sustainable agriculture. Many Pseudomonas spp. control plant pathogens and play an effective role in disease management through direct and indirect mechanisms. Pseudomonas spp. fix the amount of atmospheric nitrogen, solubilize phosphorus and potassium, and also produce phytohormones, lytic enzymes, volatile organic compounds, antibiotics, and secondary metabolites during stress conditions. These compounds stimulate plant growth by inducing systemic resistance and by inhibiting the growth of pathogens. Furthermore, pseudomonads also protect plants during different stress conditions like heavy metal pollution, osmosis, temperature, oxidative stress, etc. Now, several Pseudomonas-based commercial biological control products have been promoted and marketed, but there are a few limitations that hinder the development of this technology for extensive usage in agricultural systems. The variability among the members of Pseudomonas spp. draws attention to the huge research interest in this genus. There is a need to explore the potential of native Pseudomonas spp. as biocontrol agents and to use them in biopesticide development to support sustainable agriculture.

Endophytes and Plant Extracts as Potential Antimicrobial Agents against Candidatus Liberibacter Asiaticus, Causal Agent of Huanglongbing.

Huanglongbing (HLB), also known as citrus greening, is an insidious disease in citrus and has become a threat to the sustainability of the citrus industry worldwide. In the U.S., Candidatus Liberibacter asiaticus (CLas) is the pathogen that is associated with HLB, an unculturable, phloem-limited bacteria, vectored by the Asian Citrus Psyllid (ACP, Diaphorina citri). There is no known cure nor treatment to effectively control HLB, and current control methods are primarily based on the use of insecticides and antibiotics, where effectiveness is limited and may have negative impacts on beneficial and non-target organisms. Thus, there is an urgent need for the development of effective and sustainable treatment options to reduce or eliminate CLas from infected trees. In the present study, we screened citrus-derived endophytes, their cell-free culture supernatants (CFCS), and crude plant extracts for antimicrobial activity against two culturable surrogates of CLas, Sinorhizobium meliloti and Liberibacter crescens. Candidates considered high-potential antimicrobial agents were assessed directly against CLas in vitro, using a propidium monoazide-based assay. As compared to the negative controls, statistically significant reductions of viable CLas cells were observed for each of the five bacterial CFCS. Subsequent 16S rRNA gene sequencing revealed that each of the five bacterial isolates were most closely related to Bacillus amyloliquefaciens, a species dominating the market of biological control products. As such, the aboveground endosphere of asymptomatic survivor citrus trees, grown in an organic orchard, were found to host bacterial endophytes capable of effectively disrupting CLas cell membranes. These results concur with the theory that native members of the citrus microbiome play a role in the development of HLB. Here, we identify five strains of Bacillus amyloliquefaciens demonstrating notable potential to be used as sources of novel antimicrobials for the sustainable management of HLB.

Susceptibility of Duponchelia fovealis Zeller (Lepidoptera: Crambidae) to different entomopathogens in laboratory conditions

ABSTRACT Duponchelia fovealis Zeller, is currently considered one of the most important emergent pests of a range of crops. This pest is common in Europe, but its presence in the Americas, particularly Brazil and Mexico, has been only recently reported in strawberry crops. Since its recent arrival in Mexico interest in the potential of different entomopathogens for the control of D. fovealis has increased. Here we evaluated commercial products of the bacterium Bacillus thuringiensis; three different species of entomopathogenic nematodes; and different isolates of four species of entomopathogenic fungi. All pathogens were evaluated against 3rd instar larvae, except nematodes which were evaluated against both larvae and pupae. Analysis revealed significant differences in virulence amongst B. thuringiensis products, where the most virulent was nine times more virulent than the least virulent product. Amongst nematodes, Heterorhabditis bacteriophora was the most virulent and larvae were more susceptible to nematodes than pupae; larval mortalities at the highest dose evaluated (200 infective juveniles [IJs]) were between 80 and 95%, while for pupae they were between 25 and 40%. Mortality of larvae due to entomopathogenic fungi was lower than for the other entomopathogens; the highest mortality observed was 25% caused by an M. anisopliae isolate, although this was not statistically different to other fungal isolates. Overall, our results showed that biological control products based on B. thuringiensis or the nematode H. bacteriophora have the greatest potential; we consider that H. bacteriophora could be more convenient as it infects larvae and pupae.

Survey of Pest Management Practices on US Golf Courses

Integrated pest management (IPM) is an important component of golf course maintenance and includes conventional chemical pesticide use as well as nonchemical cultural management practices. Determining how frequent pest management practices are used on golf courses is critical when developing educational and outreach programs. The objective of this study was to determine the frequency of pest management practices and pesticide mixing and storage facilities on US golf courses. A survey was sent to 14,033 operational US golf facilities with 10% responding. Reliance on all conventional chemical pesticides increased from 2015 to 2021. The reliance on biological control products declined to 14% and reliance on the nonpesticide practice of using plant growth regulators remained equivalent to 2015. The most common pest management practices included monitoring weather patterns and scouting for pests, with 93% of golf facilities reporting the use of both. The use of written IPM and pesticide application plans increased from 44% to 63% of golf facilities between 2015 and 2021, respectively. Generally, mixing and storage facilities remained unchanged from 2015 to 2021. US golf facilities continue to use nonchemical pest management practices, but reliance on chemical pesticides has increased.

Molecular characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus strains isolated from peanut sold in northern Togo

The contamination of agricultural products and aflatoxins synthesis can be controlled and reduced by the application of a biological control product based on atoxinogenic Aspergillus flavus strains. The purpose of this work was to select atoxinogenic Aspergillus flavus strains that can be used in the biological control of aflatoxins. Thirty-four (34) strains of Aspergillus flavus were used and the Nor-1, Ver-1, Omt-A and AflR genes involved in the aflatoxin biosynthesis pathway were sought. The growth speed and ability of atoxigenic strains to inhibit the growth of toxigenic strains were also determined. The results showed that 50% of the strains have at least one of the genes sought and the percentages of inhibition (PI) of the atoxinogenic strains varied significantly from 16.98% to 62.50% at the threshold of 5% according to the Tukey test (p-value = 0.0000136). The mycelial growth speed (VCM) of the atoxinogenic strains varied from 7.5 to 10 mm/day with an average VCM of 8.4 ± 0.05 mm/day. Strains AKA-10; AGA-8; AMAN-35; ABA-28 and AGA-46 were found to be more effective in inhibiting mycelial growth of toxigenic strains.

Reducing the risk of onion bacterial diseases: A review of cultural management strategies

AbstractOnion (Allium cepa L.) bacterial diseases can cause catastrophic crop losses. Chemical and biological control products are not curative and have mixed or limited efficacy at preventing onion bacterial diseases. Cultural management strategies, such as appropriate irrigation and nitrogen (N) management practices, can reduce the risk for bacterial infection and disease progression. This review synthesizes available literature on cultural management strategies to mitigate onion bacterial diseases and identifies knowledge gaps, promising strategies, and limitations. This synthesis revealed that high N fertilizer application rates, the use of overhead irrigation, and late‐season irrigation or rainfall, especially during field curing, can increase bacterial disease pressure. These factors contribute to conducive conditions for bacteria to colonize the foliage and neck of onion plants. Other in‐season strategies, such as reducing the total amount of irrigation or adjusting application rates of nutrients other than N, have not limited losses to bacterial bulb rots while maintaining desired yields. At the end of the growing season, appropriate timing of lifting bulbs (undercutting to sever the roots) and other practices that speed field curing can reduce the risk of bacterial bulb rots. However, it is less clear if topping (removing foliage) before or after curing influences bacterial bulb rots. Conflicting results reported for some cultural management strategies indicate that local conditions, such as climate and soil types, must be considered for optimizing practices to manage onion bacterial diseases. Advancing our scientific understanding and grower awareness of strategies that reduce onion bacterial diseases is a cost‐effective opportunity to avoid losses.

Making the best of research investment in pathogens control through biocontrol. How is research correlated with agricultural microbial biological control product availability?

While using microbial biological control products (MBCPs) to limit pathogens is one of the alternatives to the ecologically unsustainable use of synthetic pesticides that received attention, the last 2 decades have not brought the foreseen leap in developing systematic alternatives based on low-risk plant protection products (PPPs) across the globe. To explain this limited progress, we map the evolution of research on the most successful microbial biological control agents (MBCAs) worldwide. We also map the financing structure in the top funding countries and the European Union (EU) to discern the relevant trends. Available data for the European Union Member States allowed us to discover a country-level and EU-level correlation between strain-level research and biocontrol products' approval based on those strains.

Points to consider in seeking biosafety approval for research, testing, and environmental release of experimental genetically modified biocontrol products during research and development

Novel genetically modified biological control products (referred to as “GM biocontrol products”) are being considered to address a range of complex problems in public health, conservation, and agriculture, including preventing the transmission of vector-borne parasitic and viral diseases as well as the spread of invasive plant and animal species. These interventions involve release of genetically modified organisms (GMOs) into the environment, sometimes with intentional dissemination of the modification within the local population of the targeted species, which presents new challenges and opportunities for regulatory review and decision-making. Practices developed for GMOs, primarily applied to date for GM crops may need to be adapted to accommodate different types of organisms, such as insects, and different technologies, such as gene drive. Developers of new GM biocontrol products would benefit from an early understanding of safety data and information that are likely to be required within the regulatory dossier for regulatory evaluation and decision making. Here a generalizable tool drawing from existing GM crop dossier requirements, forms, and relevant experience is proposed to assist researchers and developers organize and plan their research and trialing. This tool requires considering specifics of each investigational product, their intended use, and country specific requirements at various phases of potential product development, from laboratory research through contained field testing and experimental release into the environment. This may also be helpful to risk assessors and regulators in supporting their systematic and rigorous evaluation of new biocontrol products.

Biological impact, oxidative stress and adipokinetic hormone activities of Agrotis ipsilon in response to bioinsecticides

The use of biological control products enhances the reduction of harmful pressures on the environment caused by the use of conventional pesticides. Therefore, this study aims to evaluate the toxicity of eight bioinsecticides on the black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) to understand the relationships between insecticide exposure and insect response at the individual and population levels. The bioassay results showed that emamectin benzoate had high toxicity against A. ipsilon second instar larvae with an LC<sub>50</sub> of 0.007 (mg/L). Sublethal concentration (LC<sub>30</sub>) of emamectin benzoate, spinosyn group and Bacillus thuringiensis formulation (Dipel 2X) had significantly prolonged pupal period. In addition, emamectin benzoate significantly decreased the number of eggs laid per female (135.3 ± 6.919) compared with the control treatment. Thus, the formulation of chlorfenapyr showed a 1.26-fold reduction in hatching rate. Meanwhile, the activities of oxidative stress enzymes (catalase, superoxide dismutase, lipid peroxidase, and glutathione reductase) were significantly affected due to exposure to sublethal concentration. Changes in adipokinetic hormone (AKH) transcriptional regulation were detected via SQ-PCR via using cDNA synthesized from mRNA isolated from treated A. ipsilon larvae. The results showed a higher transcription rate of AKH in spinotram-treated larvae with a 1.42-fold increase over untreated larvae. Our results provide useful information for integrated pest management programs for A. ipsilon by using bioinsecticides.

Mycotoxin levels and characterization of natural anti-fungal phytochemicals in pearl millet (Pennisetum glaucum) from Nigeria's six agroecological zones.

This study reports levels of multiple mycotoxins across Nigeria's six agro-ecological zones and corresponding levels of natural anti-fungal phytochemicals present in pearl millet (PM). 220 representative composite samples of PM were collected for mycotoxin analysis using ultrahigh performance liquid chromatography-mass spectrometry (UHPLC-MS), and 24 were randomly selected for determination of metabolites using gas chromatography-high resolution time of flight-mass spectrometry (GC-HRTOF-MS). In total, 15 mycotoxins were detected, all with levels below the European Union (EU) permissible limits and level of aflatoxins only up to 1.34µg/kg. This is in sharp contrast to high levels of mycotoxins reported in maize samples from the same agroecological zones. Phytochemical analysis of the same samples identified a total of 88 metabolites, 30 of which are known anti-fungal properties from other previously published studies. The most common of these include methyl ester, bis (2-ethylhexyl) phthalate, and ç-tocopherol. The number of anti-fungal metabolites recovered from each sample ranged from 3 to 17 and varied widely in both number and composition across the agroecological zones. The anti-fungal metabolites may probably make PM less susceptible to fungal proliferation compared to other grains. Hence, it is worth exploring for possible sources of biological control products from PM.

Genetic Diversity of Aspergillus flavus Associated with Chili in Nigeria and Identification of Haplotypes with Potential in Aflatoxin Mitigation.

Dried red chili (Capsicum spp.), a widely produced and consumed spice in Nigeria, is often contaminated by aflatoxins. Aflatoxins are potent mycotoxins of severe health and economic concern worldwide. Aspergillus flavus often contaminates crops with aflatoxins in warm regions; however, not all isolates are aflatoxin producers. Nonaflatoxigenic isolates have potential as biocontrol agents for aflatoxin mitigation. The current study examined the genetic diversity of A. flavus (n = 325) associated with chilies in Nigeria and identified 123 nonaflatoxigenic isolates. The Nigerian A. flavus isolates from chili were diverse at 17 microsatellite loci, with 5 to 36 alleles per locus, and included 152 haplotypes. The isolates that are active ingredients in Aflasafe, registered for aflatoxin biocontrol on maize and groundnuts in Nigeria, did not share haplotypes with the chili isolates. Of the 152 haplotypes, 65% produced aflatoxins in autoclaved maize, some of which (17%) produced >100,000 µg/kg of aflatoxins. Aflatoxins were not detected in 35% of the haplotypes. Cluster amplification pattern assay detected large deletions in the aflatoxin biosynthetic clusters of some (32%) of the nonaflatoxigenic haplotypes. Coinfection of chili with nonaflatoxigenic isolates from chilies (n = 7) and A. aflatoxiformans resulted in a significantly greater average reduction in total aflatoxins compared with that achieved by Aflasafe active ingredient isolates (P < 0.01). These nonaflatoxigenic isolates are a genetic resource for the development of biological control products for aflatoxin mitigation in chilies in Nigeria and should be evaluated under field conditions.