Diversity and sampling methods for hymenoptera in a watermelon crop in the semiarid region

Abstract

The aims of this study were to identify the Hymenoptera fauna associated with watermelon crops and assess the influence of Pitfall, Moericke and McPhail traps in capturing these insects in the semiarid environment of the state of Rio Grande do Norte, Brazil. The survey was conducted between the months of August and September, 2011, in a commercial watermelon cv Crimson Sweet production area. The collection of the Hymenoptera was conducted weekly during the crop cycle. To capture the insects, three types of traps were used, Pitfall, Moericke and McPhail, in densities 20, 20 and 1 trap per hectare, respectively. The traps were installed seven days after seeding and maintained in the area until harvest. A total of 3,123 Hymenoptera were collected, belonging to 10 superfamilies, and 24 families. Formicidae was the most representative, with a total relative abundance of 54.43%, followed by Apidae with 17.96%. The presence of 18 families of parasitoids (18.89%) was also observed, notably Platygastridae (6.60%), Encyrtidae (2.79%), Chalcididae (2.56%), Mymaridae (2.56%), Pompilidae (1.15%) and Trichogrammatidae (1.09%). The occurrence of predators from the families Crabronidae (6.34 %), Vespidae (2.24 %) and Sphecidae (0.10%) is noteworthy. Among the traps, Moericke captured the greatest diversity of Hymenoptera (24 families), followed by Pitfall (11 families) and McPhail (seven families) traps. © 2016, Sociedade de Olericultura do Brasil. All rights reserved.