Occurrence of chlorpyrifos and organochlorine pesticides in a native bumblebee (Bombus pauloensis) living under different land uses in the southeastern Pampas, Argentina

Abstract

Pollinators such as Apidae bees are vital for ecosystems and food security. Unfortunately, their populations have declined due to several factors including pesticide use. Among them, the organophosphate insecticide chlorpyrifos, poses a global threat, while legacy compounds like organochlorine pesticides (OCPs) easily bioaccumulate, increasing the concern. Bombus pauloensis, a widely distributed native bee in Argentina, is used for commercial pollination; however, information regarding their health status is scarce. This study assessed chlorpyrifos and OCP levels in B. pauloensis (workers and males) and related environmental matrices living from three different land uses schemes, by means of GC-ECD and GC–MS. The ornamental horticulture field (OP) showed the highest total pesticide concentrations in workers (13.1 ng/g), flowers and soils, whereas the organic agriculture field (OA) exhibited the lowest. Chlorpyrifos was the most abundant compound, accounting for at least 20 % of pesticide load across all matrices. The food production horticulture field (FH) had the highest chlorpyrifos concentration in workers, males and soils (5.0, 4.4 and 3.3 ng/g, respectively), suggesting a local greater usage, whereas OA showed the lowest. Regarding OCPs groups, Drins and DDTs were predominant in most matrices, with FH males registering the highest levels (4.0 and 2.5 ng/g, respectively), closely followed by OP. However, metabolites´ contribution indicated historical use and atmospheric inputs in all sites. Multivariate analyses confirmed the significance of site and bumblebee sex to explain pesticide composition. Males from all sites exhibited higher chlorpyrifos levels than workers and this trend was similar for some OCP groups. Overall, OA differed from FH and OP, indicating a correlation between production modes and pesticide profiles. This study demonstrates the value of B. pauloensis as a pesticide biomonitor but also offers insights into its populations´ health in the area. In this sense, this information could be useful towards the preservation of this crucial pollinator.