Escarabajo ‘Cerotoma ruficornis’ - ‘Cerotoma ruficornis’ beetle.

The beetle I show in the photographs, I found it in a clearing with low vegetation while ascending a mountain. It belongs to the family Chrysomelidae, subfamily Galerucinae, tribe Luperini, subtribe Diabroticina, genus Cerotoma. The genus Cerotoma, according to a database, includes 5 species: Cerotoma arcuata, Cerotoma atrofasciata, Cerotoma ruficornis, Cerotoma trifurcata and Cerotoma variegata, although it has also been documented in the scientific literature that the genus contains 10 to 12 species (among them, Cerotoma eburifrons) distributed from southern Brazil to the northeastern United States.

Among species there are morphological variations in the patterns and coloration of the elytra, and even within the same species variations can be found (intraspecific variation), that is, there are large differences between individuals. For example, Cerotoma atrofasciata and Cerotoma ruficornis species are very variable and can show a very diverse coloration pattern of black spots on a red or yellow background, and the pattern of black spots can range from a single black spot covering the entire surface of the elytra to a complete absence of spots.

For the species Cerotoma atrofasciata, up to 5 morphological variations have been determined showing patterns with different colors of the elytra and the spots present on them: yellow color with complete spots, red color with complete spots, red color with incomplete spots, yellow color with incomplete spots and black color. In the case of the species Cerotoma trifurcata, there is also considerable variation: green with spots, green without spots, red with spots and red without spots. However, despite these 4 different color morphologies, it has been shown that they are not genetically isolated; they are the same species.

However, the beetle I show in the photographs is probably the species Cerotoma ruficornis. This species includes two subspecies: Cerotoma ruficornis subsp. ruficornis and Cerotoma ruficornis subsp. sexpunctata.

In relation to the life cycle of the Cerotoma ruficornis species, it performs a holometabolous (complete) metamorphosis that includes the well-defined stages of egg, larva, pupa and adult. Eggs, ellipsoid in shape and yellow in color, are laid in the soil under dry leaves and near the roots of seedlings or host plants. Eggs may take 5 to 8 days to hatch. Neonate, or newly hatched, larvae are milky white and then darken. In general, larvae are elongated and reach 7 to 10 millimeters in length at full development. The larval stage ranges from 21 to 31 days, and in all larval stages they feed on plant roots. Pupae are whitish in color, 4 millimeters long, are kept in a soil cell near the soil surface and take 5 to 8 days to emerge.

The adults, which can measure between 4 and 6 millimeters, feed on the foliage of plants, piercing the leaves and causing a reduction in leaf area. Among the host plants, to name a few, are the genera Phaseolus, Vigna, Glycine, Cajanus and Arachis of the Fabaceae family, and the genera Paspalum, Oryza, Zea, Sorghum and Cenchrus of the Poaceae family.

Both adults and larvae have chewing mouthparts, and in this sense, Cerotoma ruficornis, like other species of the genus, is considered a pest. As a pest, it is frequent during the rainy season and can cause great damage to crops. The adults, besides damaging the foliage of the plants, also attack the flowers. In the case of the larvae, as they develop underground, the damage is a consequence of eating the roots. Cerotoma ruficornis is also a transmitter of viruses and other plant pathogens.

Among its natural enemies, the larvae of beetles of the species Pyrophorus havanensis and Pyrophorus noctilucus (family Elateridae) feed on the soil-dwelling larvae of Cerotoma ruficornis.

Photographs captured with TECNO POP 7 (BF6) phone.