The damage caused by spittlebugs varies according to the species of grass, and the losses can reach alarming levels. Measures for population control are currently restricted to the use of resistant grasses and the diversification of pastures. Therefore, alternative control measures are necessary, such as the use of botanical insecticides. The aim of this study was to evaluate the insecticidal activities of thymol, carvacrol, eugenol, cinnamaldehyde, and trans-anethole on Mahanarva spectabilis eggs, nymphs, and adults under laboratory conditions. In the egg tests, treatments with eugenol, carvacrol, and thymol showed the highest mortalities, presenting efficiencies higher than 85% after 48 h of application. In the nymph tests, the treatments with thymol and carvacrol at 2.5% and eugenol at 2.0% and 2.5% showed intermediate efficiencies, with values above 61%. The highest mortality was observed in the treatment with trans-anethole at 2.5%, with an efficiency of 95%. In the tests with adults, only treatment with trans-anethole at 2.5% obtained an efficiency reaching 90%; in the other treatments, the efficiency did not exceed 51%. These results showed that, at these concentrations, trans-anethole presents a high rate of insecticidal activity on M. spectabilis nymphs and adults and, therefore, is recommended as a potential natural insecticide for the control of this pest.

The performance and preference of Mahanarva spectabilis (Distant) for feeding on different forage species were evaluated. The survival and duration of the nymphal period, longevity and fertility of adults, and food preferences (free choice) of adults of M. spectabilis were evaluated in a greenhouse trial, and food preferences of adults were also evaluated in laboratory tests without a choice of host plant. In the field, the numbers of plants with spittle masses were evaluated by forage sampling. Lower levels of nymph survival were observed in the greenhouse on Molasses grass, Jaraguá, Tanzânia, and Makueni. The duration of the nymphal period did not differ significantly on different forage species; however, the longevity and fertility of adults were significantly lower on Cynodon and Brachiaria decumbens Stapf. In the free-choice preference test, adult insects were attracted most strongly to B. decumbens and Jaraguá, with intermediate attraction to Brachiaria brizantha (Hochst ex A. Rich) Stapf and Pioneiro. In the test without host choice, insects exhibited lower excretion rates on Tanzânia, Cynodon, Jaraguá, B. brizantha, and Molasses grass, and those fed on Cynodon, Jaraguá, Molasses grass, and Makueni also exhibited reduced body mass. In the field, Pioneiro had the highest number of spittle masses, followed by Roxo de Botucatu. Thus, Molasses grass, Tanzânia, Makueni, and Jaraguá plants are less suitable food sources for M. spectabilis nymphs and adults. Additionally, although Jaraguá was less favorable to nymphs, it attracted food-seeking adults; hence, these plants have potential for use in control of M. spectabilis.

The aim of this study was to determine the favorable constant temperature range for Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) development as well as to generate geographic distribution maps of this insect pest for future climate scenarios. M. spectabilis eggs were reared on two host plants (Brachiaria ruziziensis (Germain and Edvard) and Pennisetum purpureum (Schumach)), with individual plants kept at temperatures of 16, 20, 24, 28, and 32°C. Nymphal stage duration, nymphal survival, adult longevity, and egg production were recorded for each temperature*host plant combination. Using the favorable temperature ranges for M. spectabilis development, it was possible to generate geographic distribution. Nymphal survival was highest at 24.4°C, with estimates of 44 and 8% on Pennisetum and Brachiaria, respectively. Nymphal stage duration was greater on Brachiaria than on Pennisetum at 20 and 24°C but equal at 28°C. Egg production was higher on Pennisetum at 24 and 28°C than at 20°C, and adult longevity on Pennisetum was higher at 28°C than at 20°C, whereas adult longevity at 24°C did not differ from that at 20 and 28°C. With these results, it was possible to predict a reduction in M. spectabilis densities in most regions of Brazil in future climate scenarios.

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.

In this study, we evaluate the olfactory responses of Mahanarva spectabilis adults to aqueous extracts from the following non-host plants for the pest insect: garlic (Allium sativum L.), rue (Ruta graveolens L.), cinnamon (Cinnamomum verum J. Presl), lemongrass (Cymbopogon citratus Stapf.), clove (Syzygium aromaticum L.), star anise (Illicium verum Hook.f), eucalyptus (Eucalyptus globulus Labill.), tobacco (Nicotiana tabacum L.), and thyme (Thymus vulgaris L.) applied to the host plant, elephant grass (Pennisetum purpureum Schum.). The bioassays were performed using a Y olfactometer, and the combinations of the plant extracts applied to the host plant were tested against fresh air and against the host plant without the extract. The results show that the extracts of tobacco and star anise were non-attractive to M. spectabilis adults. The extracts from the remaining plants did not alter the response of M. spectabilis to the host plant.

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.