The Impact of Beehive Proximity, Human Activity and Agricultural Intensity on Diptera Diversity in a Mediterranean Mosaic of Agroecosystems, with a Focus on Pest Species

SIMPLE SUMMARY: Diptera are rich in species, contribute significantly to plant diversity, and have the potential to assess habitat health. They also include many agricultural and forestry pests. Our study provides baseline information on Diptera and Vespidae diversity in the Mediterranean mosaic of agroecosystems. Additionally, we summarized the information on the importance of human influence on Diptera diversity. We carried out an inventory of Diptera in Croatia using a set of traps placed in the proximity of honeybee hives. We determined the presence of pests and newly introduced species. A total of 94 species belonging to 24 families were recorded, including 7 important agricultural and forest pests of Diptera and 17 new records for Croatia. Results pointed out that total insect species richness, pest species richness, and the first findings depend on human activities. Furthermore, the number of honeybee colonies was negatively correlated with total species richness, while anthropogenic influence was positively correlated with pest species richness. ABSTRACT: Diptera, with their participation in pollination, significantly contribute to the maintenance of plant diversity, and they also have great potential for assessing habitat health and preserving it. A decline in their abundance and diversity has been recorded worldwide as a consequence of biotic, abiotic, and anthropic alterations. In addition to pollinators, these orders include agricultural and forestry pests, which are a threat to both cultivated and wild plants that are very important to the economy. Many pests have escaped from their native areas, and it is important to monitor their spread to implement sustainable means of control. Our study provides baseline information on Diptera and Vespidae diversity in the Mediterranean mosaic of agroecosystems, giving information on the importance of human influence on insect diversity. We carried out an insect inventory in Istria, Croatia, using a set of traps placed in the proximity of beehives. This study was also important in determining the presence of pests and newly introduced species. A total of 94 species from 24 families were recorded—7 important agricultural pests of Diptera and 17 new records for Croatia. The correlation between species diversity and environmental and anthropogenic factors leads to the conclusion that total insect species richness, pest species richness, and the first findings depend on human activities. The number of honeybee colonies negatively correlated with species richness, while anthropic influence positively affected total and pest species richness.