Diversidade, aspectos biológicos e morfológicos de Scarabaeoidea associados à canaviais e pastagem da região Sul de Mato Grosso do Sul

Abstract

Brazil is the world's largest producer of sugarcanes as well as positioning itself as the world leader in ethanol production technology. However, some pests previously considered secondary have become relevant to the crop, constituting one of the limiting factors for their production. Among these species of pests are the insects of the Melolonthidae family, which are responsible for about 70% of the diversity of Scarabaeoidea and represent about 4,000 species in the Neotropical region. Insects in this family are generally detritivores, which contribute to the cycling of nutrients in the soil, but can also act as pests, thus causing serious damage to crop. The assessment of the occurrence of South American Melolonthidae edaphic species, added to its taxonomic study is fundamental for this region, considered as the most diverse on the planet, despite its poorly known biodiversity, especially with regard to information on its distribution and ecology. Such studies are particularly necessary in the state of Mato Grosso do Sul, where there has been a significant increase in the abundance and richness of melolontids in both sugarcane and other crops. In addition to melolontids, scarab beetles (Coleoptera: Scarabaeinae) are also widely used as ecological indicators because they respond quickly to changes caused by land use. In addition, like melolontids, they also play important ecosystem functions (e.g. nutrient cycling) due to copronecrophagous eating habits and the behavior of burying food in the soil. However, the quality of the collection of adults in this group through a pitfall trap can be compromised, due to problems such as predation of the collected insects and the piloting of attractive baits. Thus, this thesis is divided into three chapters with sampling carried out in the region of Dourados (22º19'00 ” S 54º58'23” W) and in Deodápolis (21 ° 52 'S and 54 ° 01' W), in the state of Mato Grosso do Sul, Brazil, during the years 2017 and 2018. The first chapter reports a new occurrence of Plectris aliena (Coleoptera: Melolonthidae) in Deodápolis, and presents its biological and morphological aspects. In this location, 950 larvae were sampled through trenches carried out on the ground and 103 adults were collected using a light trap. A new parameter for the characterization of the sexual dimorphism of P. aliena was presented. The morphological data of adults and immatures presented in this chapter can assist in the identification of this species in field conditions. The occurrence of adults in light traps suggests that males are phototropic positive for artificial light. The seasonal distribution of P. aliena showed that the species is univoltine, with a predominance of third instar larvae from February to April, months in which monitoring of this species is recommended in sugarcane areas in Mato Grosso do Sul. In the second chapter, the abundance of melolontids beetles in cane fields captured in Dourados and Deodápolis were reported. Adults were collected using a light trap (“Luiz de Queiroz” model). In total, 5,182 adults were collected, belonging to 10 genera and 16 species, grouped into 7 tribes. Cyclocephala signaticollis Burmeister, 1847, Phyllophaga capillata (Blanchard), Isonychus albicinctus Blanchard, 1850 and Dyscinetus rugifrons Burmeister, 1847 were recorded for the first time in Mato Grosso do Sul. In addition, an identification key for subfamily, tribe, genus and species was also developed in this Thesis. We believe that the results obtained in this chapter may contribute to a better understanding of the composition of the melolontid beetle community and the distribution of species with the potential to become pests in sugarcane fields in Mato Grosso do Sul. In the third chapter, we present a survey of Scarabaeinae species occurring in two locations, in Mato Grosso do Sul, using a modified pitfall trap. Galvanized iron materials, polypropylene collector, water solution, formaldehyde (4%) and neutral detergent were used. The experimental work presented here provides one of the first investigations on the Scarabaeinae complex collected with a modified pitfall trap, associated with different types of baits in Dourados - MS. It is hoped that this research will contribute to a deeper understanding of the role that this group of insects plays as bioindicators and functions in the ecosystem.