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ABSTRACT: The occurrence of African planthopper Leptodelphax maculigera (Stål 1859) (Hemiptera: Delphacidae) was first reported in Brazil in the Central-West region, Goiás state, Brazil, in 2023. However, it is important to analyze its dispersion in the country, frequency of occurrence and the sites of emergence in maize crop environments. This study reports the co-occurrence of L. maculigera and Dalbulus maidis in the Minas Gerais state and their frequencies in the maize agroecosystem, including the weed community. In addition, it reports the presence of parasitized L. maculigera individuals, suggesting the adaptation of local natural enemies to this species. In relation to D. maidis, which has a high frequency in maize crops, L. maculigera showed a low frequency in the crop and a moderate frequency in the weed communities. The proportion of African planthopper, at field level, along the maize developmental stages V1 to V7 presented an average frequency 97 % smaller than that of D. maidis.

KEYWORDS: Zea mays L, African planthopper, corn stunt disease complex.

RESUMO: A ocorrência da cigarrinha africana Leptodelphax maculigera (Stål 1859) (Hemiptera: Delphacidae) foi relatada pela primeira vez no Brasil na região Centro-Oeste, estado de Goiás, Brasil, em 2023. No entanto, é importante analisar sua dispersão no país, frequência de ocorrência e onde está presente na cultura do milho. Este trabalho relata a co-ocorrência de L. maculigera e Dalbulus maidis no estado de Minas Gerais e suas respectivas frequências na cultura do milho e na comunidade de plantas daninhas. Além disso, relata a presença de indivíduos de L. maculigera parasitados, indicando a adaptação de inimigos naturais locais a esta espécie. Em relação a D. maidis, que tem alta frequência na cultura do milho, L. maculigera apresentou baixa frequência na cultura e frequência moderada em comunidades de plantas daninhas. A proporção de cigarrinha africana, em nível de campo, ao longo dos estágios de desenvolvimento do milho V1 a V7 apresentou frequência média 97 % menor que a de D. maidis.

PALAVRAS-CHAVE: Zea mays L, cigarrinha africana, doenças do complexo do enfezamento do milho.

Ferreira et al. (2023) first reported the occurrence of African planthopper Leptodelphax maculigera (Stål, 1859) (Hemiptera: Delphacide) in the Central-West region of Brazil (Goiás state) in species of agronomic importance, such as maize, brachiaria, elephant grass, the BRS Capiaçu cultivar and bean. Then, Bortolotto et al. (2023) reported L. maculigera in the southern region of Brazil, where samples collected from maize and wheat fields carried the Maize Rayado Fino Virus (MRFV). Also, Canale et al. (2024) detected Maize Bushy Stunt Phytoplasma (MBSP) in the Santa Catarina state and MRFV and Maize Striate Mosaic Virus (MSMV) in African planthopper samples in maize fields. Stürmer et al. (2024) detected MRFV and MBSP in L. maculigera populations in the Rio Grande do Sul state.

MBSP (Bedendo et al. 2000), MRFV (Hammond & Bedendo 2005) and MSMV (Fontenele et al. 2018) are associated with corn stunt complex in maize, with the Dalbulus maidis (DeLong & Wolcott 1923) (Hemiptera: Cicadellidae) leafhopper being their main vector in maize crops (Oliveira et al. 2013).

Although L. maculigera carries these pathogens, studies are needed to verify whether it has the ability to transmit them to maize. It is also important to conduct studies on its dispersion in Brazil, its frequency of occurrence and the sites of occurrence in maize crop environments. Thus, this study reports the co-occurrence of L. maculigera and D. maidis in the Minas Gerais state and their frequencies in the maize agroecosystem, including the weed community, with Sete Lagoas being the first place where the African planthopper was found in a field with volunteer maize where D. maidis population was low.

Figures 1 and 2 show L. maculigera species according to Bartlett (2020). During the survey in Sete Lagoas, four individuals were obtained parasitized by Dryinidae, evidenced by the typical external larval sac (Martins & Domahovski 2022), suggesting activity of biological control agents (Figure 3). Unfortunately, these individuals died, what did not allow confirmation of the parasite species. All insect photos were taken using a stereo microscope with a magnification of 30x.

Due to this identification, this study sought different maize production areas in the south-center region of the Minas Gerais state (Figure 4). The insect samples were collected using a sweep net with six strokes, over 10 linear meters, and repeated three times. The sampling survey was carried out once at the south-center municipalities from April 16 to 19, 2024, in maize and wheat crops, volunteer maize, and brachiaria or weed plants at the crop edge (Table 1). Among the sampled areas, the African planthopper was collected in maize crop at the R1 stage and in wheat crop at the vegetative stage, in the municipality of São João del Rei, and at the vegetative stage in wheat in the municipality of Madre de Deus de Minas. The ratios of D. maidis to L. maculigera individuals were 24:1, 1:1 and 0:1, respectively.

The occurrence and frequency of D. maidis and L. maculigera and weed community were evaluated in a 5-ha experiment with three maize hybrids (AG7098 TRE, BM953 PRO4 and AG8480 PRO3) at the V5 to V8 developmental stages and the BR 451 cultivar (V1 to V7) during March and May 2024, at the Embrapa Milho e Sorgo, in Sete Lagoas, Minas Gerais state (Tables 2, 3 and 4; Figure 5).

The crop treatments were carried out according to the technical recommendations for the crop (Cruz et al. 2010). The insect sampling was performed weekly in the morning, using an entomological net with ten blows in pendular forward movements (180 º) at 12 random points to sweep the plant canopy and weed plants. The weed community in the crops was at the V4 stage of the maize plants. These evaluations were performed by randomly throwing 25 times a 0.5-m² metal sheet across the useful area of each plot. The weed plants were collected and separated by species. The density and dry mass values were determined. The plants were sectioned close to the ground and dried in an oven with forced air circulation at a temperature of 70 ºC, until constant mass.

Twenty weed species belonging to nine botanical families were identified: Amaranthaceae, Asteraceae, Commelinaceae, Convolvulaceae, Euphorbiaceae, Poaceae, Portulacaceae, Rubiaceae and Solanaceae (Table 3). The Poaceae and Asteraceae families presented the greatest diversity of species. In addition to quantifying the species and the total number of individuals per sampled area, the following phytosociological parameters were calculated: relative frequency, relative density, relative dominance and relative importance index, as proposed by Silva et al. (2005) and Concenço et al. (2013) (Table 4). The phytosociological analysis showed that Amaranthus spp., Cenchrus echinatus, Panicum maximum and Parthenium hysterophorus were the species with the highest relative importance index in the maize crops.

The frequency of D. maidis was higher in the AG7098 TRE, BM953 PRO4 and AG8480 PRO3 maize hybrids and in the BR 451 cultivar than in the weeds. The opposite occurred for L. maculigera, with low frequency in the maize and a moderate frequency in the weeds (Table 2; Figure 5).

Stürmer et al. (2024) evaluated the population level of D. maidis and L. maculigera during the 2023/2024 maize crop season in South Brazil, Rio Grande do Sul state, and reported a low frequency for African planthopper. These findings suggest that, despite being present in the environment where maize grows, the African planthopper does not occupy the niche of the maize leafhopper D. maidis within the plant’s whorl. Furthermore, the proportion of L. maculigera African planthopper at field level along the developmental stages V1 to V7 of the BR 451 maize cultivar had an average frequency 97 % smaller than that for D. maidis. The frequency of this insect was low in the maize plants and moderate in the weed community, with prevalence of the Poaceae species. Although the African leafhopper counts maize as one of its hosts (Bonfils et al. 1994), its low frequency did not show a significant variation in fluctuation throughout the maize crop development.

Considering the low frequency of L. maculigera in the maize and the moderate frequency in the weeds, associated to the fact that this insect carries the pathogens of the corn stunt complex MBSP and the MRFV and MSMV viruses (Bortolloto et al. 2023, Canale et al. 2024, Stürmer et al. 2024), further studies are needed to verify whether it is a vector of pathogens. For the development of an integrated management program with effective actions, studies are necessary on insect bioecology and weeds management, in order to reduce the population density of this insect in crops.

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