Fall armyworm (FAW), Spodoptera frugiperda, is a migratory polyphagous pest that causes major damage to economically important cultivated grasses, such as corn. Native to the neotropics in America but recently reported as an invasive pest in Africa and Asia, FAW imposes a serious threat to food security and sustainable crop productivity due to lack of effective management. In this study, the introduction of entomopathogenic fungi as endophytes was explored as an alternative more sustainable management strategy against FAW in corn. The study determined (1) the effect of isolates and inoculation methods on the ability of entomopathogenic fungi to colonize corn plants, and (2) the effect of colonized plants on S. frugiperda survival, development, reproduction, and food preference. Although all tested isolates (twelve of Beauveria bassiana and one each of Metarhizium anisopliae and Metarhizium robertsii) colonized inoculated plants, there was a highly significant interaction between isolates and inoculation methods. Highest plant colonization was obtained by Beauveria bassiana isolate (LPSc 1098) using foliar spray. Endophytic B. bassiana caused significant reductions in larval and pupal survival, length of different developmental stages, total S. frugiperda lifespan, and leaf area consumed by third instar larvae. Plant colonization also significantly reduced female longevity, fecundity, and fertility. This is the first report for the negative effects of endophytic B. bassiana on S. frugiperda growth, reproduction, and food preference. Our results highlight the promising potential of incorporating entomopathogenic fungi as endophytes in integrated pest management practices to protect corn against FAW if their efficacy is also confirmed under field conditions.

Entomopathogenic fungi are widely recognized as agents of biological control worldwide. Their use in agriculture for the regulation of pest populations is a promising alternative to conventional insecticides. Furthermore, recent studies have shown that entomopathogenic fungi fulfill an additional role in plants as growth promoters. The purpose of this investigation was to assess the growth and yield of corn plants colonized with Beauveria bassiana and its effect on the lepidopteran pest Rachiplusia nu. Effects of the fungus on plant growth, crop yield, and vertical transmission were evaluated in the field. Feeding preferences of R. nu larvae were assessed in the laboratory using a “choice test”. Corn plants inoculated with B. bassiana showed an increase in height, number of leaves, grain weight, yield, and percentage of seed germination compared to control plants. Consumption of B. bassiana-colonized corn plants by R. nu larvae was reduced compared to feeding levels observed on non-inoculated plants. This study showed that endophytic B. bassiana can provide multiple benefits to Zea mays and can play an important role in future integrated pest management programs.

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Endophytic fungi are ubiquitous and live within host plants without causing any noticeable symptoms of disease. Little is known about the diversity and function of fungal endophytes in plants, particularly in economically important species. The aim of this study was to determine the identity and diversity of endophytic fungi in leaves, stems and roots of soybean and corn plants and to determine their infection frequencies. Plants were collected in six areas of the provinces of Buenos Aires and Entre Ríos (Argentina) two areas were selected for sampling corn and four for soybean. Leaf, stem and root samples were surface-sterilized, cut into 1cm(2) pieces using a sterile scalpel and aseptically transferred to plates containing potato dextrose agar plus antibiotics. The species were identified using both morphological and molecular data. Fungal endophyte colonization in soybean plants was influenced by tissue type and varieties whereas in corn plants only by tissue type. A greater number of endophytes were isolated from stem tissues than from leaves and root tissues in both species of plants. The most frequently isolated species in all soybean cultivars was Fusarium graminearum and the least isolated one was Scopulariopsis brevicaulis. Furthermore, the most frequently isolated species in corn plants was Aspergillus terreus whereas the least isolated one was Aspergillus flavus. These results could be relevant in the search for endophytic fungi isolates that could be of interest in the control of agricultural pests.

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In this study, the effects of strain Beauveria bassiana (LPSC 1067) as an endophyte in corn plants on consumption, fecundity, and food preference of Dichroplus maculipennis were examined. We observed that the daily consumption by grasshoppers fed with control plants was almost twice that of those that were fed treated plants. Significant differences in fecundity of grasshoppers that were fed with treated plants compared with those that only fed on control plants were also observed. The number of eggs laid per female fed with control plants was 27.2, while the number of eggs laid per female that were fed during 15 d with treated plants was 17.7. Similar results were observed when the number of embryonated eggs was evaluated. The highest number of embryonated eggs were recorded in those females that only fed on control plants (96%) while fewer embryonated eggs were recorded in grasshoppers fed for 15 d with treated plants only (25%). In relation to food preference the average consumption rate for D. maculipennis females on control corn plants was 303.8 ± 24.5 mg while it was only 25 ± 2.1 mg on plants treated with B. bassiana as an endophyte. In summary, we observed that B. bassiana as a corn plant endophyte negatively affected the daily consumption rate, fecundity and food preference of D. maculipennis.

Aphids (Hemiptera: Aphididae) are serious pests of crops causing direct damage by feeding and indirect by the transmission of plant viruses. The use of conventional insecticides for controlling aphids has caused different problems and insecticide resistance. Accordingly, there is more interest in alternative control methods such as biological control by natural enemies for sustainable agricultural management. Among biological control agents, entomopathogenic fungi are one of the most significant microbial pathogens of insects. Also, Coccinellidae, as a major group, is a serious natural enemy. Both larval and adult stages of Coccinellidae feed on different soft-body pests, such as aphids. Eriopis connexa (Germar) (Coleoptera: Coccinellidae) is a common species in agroecosystems of the Neotropical region where it is considered to be a potential control agent. Pathogens and arthropod natural enemies may contribute to the control of phytophagous pests; however, it is important to assess potential interactions within biological control agents that share hosts (intraguild interaction) to evaluate their combined use for pest control. Therefore, the aim of this study was to evaluate the compatibility and interaction (lethal and sublethal effects) between E. connexa and the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales). Both are important biological control agents of aphids. The pathogenicity of B. bassiana against larvae, pupae and adults of the predator E. connexa was evaluated, and results showed, that B. bassiana infected the coleopteran. On the other hand, interaction between B. bassiana and the predator was evaluated through infected-prey. The effects of fungus on larvae survival were significantly different when we analyzed the accumulated survival (from first larval instar to adulthood). The daily fecundity was significantly reduced at five days compared to control group. By contrast, no significant differences were observed between the five oviposition days in the rate of hatched eggs. This study shows that despite having received a single dose of the fungus in its life cycle, the population parameters of the predator E. connexa are affected. More studies would be necessary to help identify interactions between microbes and natural enemies to increase and enhance opportunities and further develop biological pest control programs.

Introduction: Entomopathogenic fungi have been used as biological control agents of insect pests and have demonstrated a promising ability to colonize as endophytes a wide range of plant species. Objective: The aims of this study were to evaluate, in pepper plants, the most effective Beauveria bassiana inoculation techniques. In order to evaluate the presence of natural endophytes and its interaction with B. bassiana. Also to assess the effect of B. bassiana on the aphid Myzus persicae pepper leaf feeding preference and growth. Methods: Three inoculation techniques were evaluated: leaf spraying, seed immersion and root dipping. The pepper plants were inoculated with a conidia suspension adjusted to 1×108 conidia/ml. The presence of B. bassiana in the seedlings was evaluated at 7, 15 and 28 days after inoculation. Results: We found significant statistical differences between inoculation techniques. Foliar spraying showed the highest B. bassiana colonization frequency. The natural endophytes presented higher presence in the treatments in which B. bassiana had a low presence. This might indicate the occurrence of antifungal activity that interferes with the establishment of the entomopathogen in pepper tissues. We did not find statistical differences between inoculated and control pepper leaves with regard to the mortality and reproduction of the aphid pest M. persicae. However, the inoculation with B. bassiana showed a tendency to increase the mortality of adults and to decrease the offspring (nymphs). We did not find significant differences in the feeding preference between inoculated and control leaves, although there was a higher number of individuals on control leaves compared to those inoculated. Conclusions: The strain B. bassiana LPSC 1067 was established effectively as an endophyte in the pepper tissues. The most effective inoculation technique was leaf spraying. We did not find differences of statistical significance with regard to the mortality and reproduction of the aphid pest M. persicae. However, the inoculation with B. bassiana showed a tendency to increase the mortality of adults and to decrease the offspring (nymphs). Future studies evaluating the indirect effects of endophytic entomopathogens on both plants and herbivorous insects are needed to further explore their potential use in the management of insect pests.