Michelle Oliveira Campagnani

Urochloa ruziziensis (R. Germ. and C.M. Evrard) Crins (synonym Brachiaria ruziziensis) Poales: Poaceae) pastures are often attacked by spittlebugs, compromising their biomass for livestock usage. A sustainable control method involves the use of entomopathogenic fungi. Therefore, the objective of this study was to evaluate the efficacy of controlling Mahanarva spectabilis Distant, 1909 (Hemiptera: Cercopidae), in greenhouse and field conditions via endophytic entomopathogenic fungi. In the greenhouse, the mortality of nymphs and adults was 100%, and more than 53% of the nymphs and 59% of the adults that fed on plants inoculated with Fusarium multiceps and Metarhizium anisopliae presented with these fungi in their cadavers. In the field, more than 45% of the insect cadavers that had fed on plants grown from fungus-treated seeds were found to contain the fungi. F. multiceps was found to be endophytic in more than 60% of the plants up to 90 days after seed treatment, and M. anisopliae was found in more than 70% of the plants up to 120 days after treatment. The damage scores of the control plants, both in the greenhouse and in the field, were greater than those of the plants inoculated with the fungi. F. multiceps and M. anisopliae in the endophytic pathway of U. ruziziensis are therefore efficient at controlling spittlebugs.

Plutella xylostella L., 1758 (Lepidoptera: Plutellidae) and Brevicoryne brassicae L., 1758 (Hemiptera: Aphididae) are important pests of Brassicaceae, causing significant damage that makes human consumption of these vegetables impossible. As an alternative to the use of chemical insecticides, this study aimed to (i) evaluate the endophytic capacity of the native fungi Fusarium multiceps (Hypocreales: Nectriaceae) and Metarhizium anisopliae (Metschn.) Sorokīn (Hypocreales: Clavicipitaceae) and a commercial strain of M. anisopliae on cabbage plants (Brassica oleracea L. var. acephala) through inoculations via seed treatments, foliar spraying or root applications and (ii) evaluate the mortalities of P. xylostella and B. brassicae fed on plants treated with these fungi. Ten P. xylostella caterpillars or ten B. brassicae nymphs were used per repetition, and the infestations were quantified daily (for P. xylostella) or after 15 days (for B. brassicae). The control treatment consisted of water. The fungi M. anisopliae and F. multiceps demonstrated endophytic colonization capacities in B. oleracea through different inoculation techniques, including application via seeds, leaves and roots. This colonization resulted in the infection and consequent significant mortality of P. xylostella and B. brassicae, reinforcing the potential of these microorganisms as promising agents for biological control.

Mahanarva spectabilis (Distant) is an important pasture pest in Brazil and represents an obstacle to forage production. Elucidating the chemical signals involved in the communication of this species is essential for finding new control alternatives. Therefore, the aim of this study was to determine whether chemical signals are involved in the mating process of M. spectabilis. In the first trial, the insect's behavior was evaluated in cages with male: female ratios of 4:1 and 1:4. As soon as copulation began, the behavior of males or females around the copulating couple was recorded. In subsequent trials, the olfactory responses of males and females of M. spectabilis were evaluated in a Y-shaped olfactometer for volatiles released by males, females and mating pairs. At a male: female ratio of 4:1, there were significantly more touches by the other males of the copulating couple. The number of individuals attached to the copulating couple and the copulation time did not differ significantly in relation to the male: female ratio used. The attractiveness of males to copulating pairs was also observed in the olfactometry test, in which males were significantly attracted only to copulating pairs and to the extract of copulating pairs. The females showed no olfactory attraction to any of the odor sources offered. This shows that chemical signals are involved in the mating process of M. spectabilis.

The forage Urochloa ruziziensis ((R. Germ. and C.M. Evrard) Crins (synonym Brachiaria ruziziensis) (Poales: Poaceae)) has great potential to be adopted as pasture. However, this forage is susceptible to spittlebugs, the main insect pest of pastures in Brazil. Thus, the objective of this study was to select genotypes of U. ruziziensis resistant to Deois schach (Fabricius) and Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) through 16 cycles of recurrent selection. The resistance of 13,114 U. ruziziensis plants to spittlebugs was evaluated in experiments conducted between 2008 and 2023. Each plant was infested with six eggs of the insect pest at stage S4 and kept in a greenhouse for up to 40 days. After this period, surviving nymphs from the second to fifth instars were counted. The original population of U. ruziziensis (POP01-2008) presented a nymphal survival rate of 63%, while for the improved population (POP36-2023) the average nymphal survival rate was 32.8%. The estimated total genetic gain was 15%, and the annual genetic gain was 1%. After 16 selection cycles, in POP36-2023, approximately 63% of the genotypes (716 plants), had nymphal survival rates equal to or less than 33% and were considered resistant to D. schach and M. spectabilis nymphs.

Pests in pastures have compromised the production of biomass for feeding livestock herds. Many strategies have been applied to sustainably solve this problem. One viable and innovative technique is the delivery of entomopathogenic fungi through endophytes. Therefore, this study aimed to (i) evaluate the endophytic capacity of two entomopathogenic fungi, Fusarium multiceps UFMGCB 11443 and Metarhizium anisopliae UFMGCB 11444, in Urochloa brizantha [(Hochst. ex A. Rich.) Stapf] (Poaceae) cultivar ‘Marundu’) via foliar inoculation or seed treatment, and (ii) measure their efficiency in controlling Mahanarva spectabilis Distant, 1909 (Hemiptera: Cercopidae) in U. brizantha. In the greenhouse, the fungi colonized the tissues of U. brizantha plants when inoculated via foliar spraying or seed treatment. The fungi F. multiceps and M. anisopliae caused 88% and 97.1% epizootic effects via seed inoculation, respectively, and 100% epizootic effects via foliar inoculation. In the field, the lowest fungal dose of 0.5 kg/ha had the same effect as a fourfold greater dose, with a >86% decrease in insect pest infestation observed. In summary, the fungi F. multiceps and M. anisopliae have endophytic effects and can effectively control M. spectabilis in U. brizantha pastures.

Spittlebugs are pests that affect forage plants in tropical America, causing damage to such plants and causing significant annual losses in milk and meat production. One of the alternatives for combating these insect pests with minimal environmental impacts is the use of entomopathogenic fungi. The objectives of this research were: (i) to evaluate the endophytic potential of entomopathogenic fungi applied to Urochloa ruziziensis (R.Germ. & C.M.Evrard) Crins (synonymous with Brachiaria ruziziensis; Poaceae) through seed treatment for the control of the spittlebug species, Mahanarva spectabilis (Distant) and Deois schach (F.) (Hemiptera: Cercopidae); (ii) to analyze the efficiency of banker plants as a means of spreading the fungi to the field; and (iii) to determine the frequency of infection after the storage of treated seeds. U. ruziziensis seeds were treated with a suspension containing 1 × 10⁸ conidia of the fungi Fusarium sp. (Hypocreales: Nectriaceae), Metarhizium anisopliae (Metschn.) Sorokīn (Hypocreales: Clavicipitaceae) or a commercial strain of M. anisopliae for 30 min, after which they were planted in 2 L planters and kept in a greenhouse. The surplus of treated seeds was conditioned at 22 °C and sown monthly for 10 months. Insects were fed plants from treated seeds. The entomopathogenic fungi were found to be endophytic and to equally infect the two species of spittlebugs from pastures, M. spectabilis and D. schach, at different stages of development; however, they caused low nymphal mortality. The banker plant technique with plants from seeds treated with entomopathogenic fungi was efficient. Furthermore, it was observed that it is possible to store seeds treated with fungi for 12 months. These results open the perspective of using entomopathogenic fungi with endophytic action as an auxiliary tool in reducing the populations of pasture spittlebugs in tropical regions.

In Brazil, pastures of Brachiaria grasses are often attacked by the spittlebug Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae). Biological control of this pest insect is rarely used, in part because of a lack of diversity in commercialized pathogens effective against such pests. However, fungal infection of M. spectabilis has been noted in some tropical silvopastoral systems, which rarely have problems with pest insects. This study surveyed the fungi found in association with M. spectabilis in a silvopastoral system in Brazil and made a preliminary assessment of their virulence. Infected spittlebugs were collected in a silvopastoral system in Brazil, from which 5 types of fungi were isolated and identified by morphological analysis. Conidia of each wild fungus and a commercial strain of Metarhizum anisopliae (Metschn.) Sorokin (Clavicipitaceae) were diluted in a 1% NaCl solution at a concentration of 1×104 conidia per mL. In the laboratory, eggs and nymphs of M. spectabilis were placed in... Resumo Pastagens com Brachiaria spp. geralmente sofrem ataques severos pela cigarrinha Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae). O controle biológico desse inseto tem sido pouco utilizado, principalmente porque há poucos entomopatógenos comercialmente disponíveis. Entretanto, M. spectabilis infectada por fungos tem sido encontrada em alguns sistemas silvipastoris (SSP) tropicais, os quais raramente apresentam problemas com insetos-praga. Este estudo é uma prospecção de fungos encontrados em associação com M. spectabilis e uma análise preliminar de sua virulência. Cigarrinhas infectadas foram coletadas em um SSP no Brasil, das quais cinco tipos de fungos foram isolados e identificados por análises morfológica e molecular. Conídios de cada um dos fungos selvagens e de uma linhagem comercial de Metarhizum anisopliae (Metschn.) Sorokin (Clavicipitaceae) foram diluídos em solução de NaCl 1% a uma concentração de 104 conídios/mL. No laboratório, ovos e ninfas de M. spectabilis foram colocados em ...