Parque Nacional do Iguaçu: serviços ecossistêmicos proporcionados para a cultura da soja

Abstract

The objective of this study was to verify the importance of pollinator insects on soybean yield (Glycine max (L.) Merrill) and to investigate if the Parque Nacional do Iguaçu (PNI) acts as a source of pollinators for agricultural crops. Additionally, investigate whether it can be considered a source for natural enemies of agricultural pests. This research was conducted in the 2016/17 crop in an agricultural area adjacent to the PNI in Serranópolis do Iguaçu city, western Paraná state, Brazil. Soybean production levels of three groups of plants with different types of pollination were evaluated, evaluating the seed yield per pod, number of pods and weight of the seeds produced. In addition, the methodology involved the observation of floral visitors in loco and the collection of arthropods using active collections with a sampling network in the soybean crop, a smell trap, using the eucalyptol essence and interception trap, installed on the edge of the PNI with the soybean crop. The collected arthropods were first separated into morphospecies and then identified at the family level. Then the food habits of these families were identified, inferring which can be considered natural enemies for soybean pests. However, the potential pollinators of soybean were also identified, and whether these could be from the Conservation Unit. The number of flowers that produced pods was similar among the groups of plants, however, self-pollinated flowers produced on average less seeds compared to those that had cross-pollination. An analogous result was found regarding seed weight, that is, the cross-pollination treatment showed better productivity results, inferring that floral visitors influence the soybean yield, increasing the number of seeds per pod and seed weight. As for arthropods, it was observed that in greater distances of the PNI the richness of morphospecies decreased and the abundance increased, mainly for some pest species of the soybean. The floral visitor rates were also higher in the transects closest to the forest remnant, inferring that the forest provides resources for the maintenance of several species of arthropods. Coleoptera was the most abundant and representative order in morphospecies richness, followed by Hymenoptera and Diptera. As for the pollinators, Apis mellifera bee (Hymenoptera: Apidae) was the most abundant in the collections and observations of floral visits. Among the pest insects, Maecolaspis calcarifera (Coleoptera: Chrysomelidae) was the most abundant species. It is concluded that the PNI works by providing resources to maintain the biodiversity of arthropods, thus providing ecosystem services for agriculture, among them cross-pollination between plants, which according to the results of this study can increase the productivity of Soy.