Non-pest household arthropods as a reservoir of human opportunistic pathogens

Arthropods are recognised as potential mechanical and biological vectors for infectious diseases in outdoor environments. However, a comprehensive understanding of the indoor arthropod community diversity and of the role that their associated microbiota may have as disease vectors is largely unexplored. Here, we study the arthropod community and the associated microbiota diversity of twenty indoor environments, sampled over a period of twelve months from urban and suburban households by citizen scientists in the West Midlands (UK). We compare the arthropods diversity between environments and over the sampling months. We characterize the exogenous (exoskeleton) and endogenous (gut) bacterial communities associated with all specimens of arthropods actively captured using both a traditional culture-based and an unbiased metabarcoding approach. For the first time, we describe the exogenous and endogenous microbiota composition and diversity of 14 arthropod families found in indoor environments. We find that both the exogenous and the endogenous microbiota are potential carriers of human opportunistic pathogens, with potential implications for public health. We discover that many bacteria families are shared across the exogenous microbiota of arthropods, likely influenced by the bacteria present in the environment. Conversely, the endogenous microbiota composition is unique to the arthropod families, and likely genetically determined. We show that the metabarcoding unbiased approach is a superior tool to characterize the microbiota associated with each arthropod family. This study provides new insights into bacterial carriage in household arthropods as potential reservoirs of infectious disease.

Aboveground impacts of a belowground invader: how invasive earthworms alter aboveground arthropod communities in a northern North American forest

Declining arthropod communities have recently gained a lot of attention with climate and land-use change among the most-frequently discussed drivers. Here, we focus on a seemingly underrepresented driver of arthropod-community decline: biological invasions. For ∼12,000 years, earthworms have been absent from wide parts of northern North America, but they have been re-introduced with dramatic consequences. Most studies investigating earthworm-invasion impacts focus on the belowground world, resulting in limited knowledge on aboveground-community changes. We present observational data on earthworm, plant, and aboveground-arthropod communities in 60 plots, distributed across areas with increasing invasion status (low, medium, high) in a Canadian forest. We analyzed how earthworm-invasion status and biomass impact aboveground arthropod community abundance, biomass, and species richness, and how earthworm impacts cascade across trophic levels. We sampled ∼13,000 arthropods, dominated by Hemiptera, Diptera, Araneae, Thysanoptera, and Hymenoptera. Total arthropod abundance, biomass, and species richness declined significantly from areas of low to those with high invasion status with reductions of 61, 27, and 18%, respectively. Structural Equation Models unraveled that earthworms directly and indirectly impact arthropods across trophic levels. We show that earthworm invasion can alter aboveground multitrophic arthropod communities and suggest that belowground invasions can be important drivers of aboveground-arthropod decline.

Field Evaluation of Cypermethrin, Imidacloprid, Teflubenzuron and Emamectin Benzoate against Pests of Quinoa (Chenopodium quinoa Willd.) and Their Side Effects on Non-Target Species

During the last few years, quinoa, a traditional Andean crop, has been cultivated at low elevations where pest pressure is high and farmers resort to intensive use of insecticides. This field study investigated the impact of four insecticides (cypermethrin, imidacloprid, teflubenzuron and emamectin benzoate) on insect pests of quinoa and their side effects on the arthropod community at the coastal level of Peru, by analysing the species composition, species diversity and population density. The arthropod community was examined with pitfall traps (for ground dwelling species), plant samplings (for pests and their natural enemies that inhabit the crop), and yellow pan traps (to catch flying insects). The results demonstrated that Macrosiphum euphorbiae, Frankliniella occidentalis and Spoladea recurvalis were efficiently controlled by cypermethrin and imidacloprid; the latter compound also showed long-term effects on Nysius simulans. Teflubenzuron and emamectin benzoate proved to be efficient to control S. recurvalis. Imidacloprid had the strongest adverse effects on the arthropod community in terms of species diversity, species composition and natural enemy density as compared to the other insecticides. Findings of this study may assist farmers intending to grow quinoa at the coastal level in selecting the most appropriate insecticides under an integrated pest management approach.

MANAGEMENT OF AGROECOSYSTEMS AND FUNCTIONAL DIVERSITY OF SOIL-ASSOCIATED ARTHROPODS IN THE EASTERN AMAZON

In the Eastern Amazon, the change in vegetation cover by converting forest areas to pastures affects the diversity of arthropods, and non-conservationist management in these areas can reduce functional diversity, compromising the sustainability of the agroecosystem. Accordingly, the objective of this work was to analyze the composition of the functional groups of the arthropod community associated with the soil under different management regimes in agroecosystems in the Eastern Amazon. For this, the study was carried out in three agroecosystems, namely bean cultivation, cassava cultivation and pasture, and in an area of secondary forest used as a reference. Arthropods were captured by means of fall traps installed in the center of agroecosystems. The captured arthropods were identified at the order and family level and later grouped according to their function. A total of 19,850 individuals were collected and classified into six different functional groups: herbivores, social insects, omnivores, predators, saprophages and xylophages. The arthropods in bean and cassava cultivation agroecosystems were more abundant and diversified in most functional groups. The results revealed that agroecosystems with crop rotation and intercropping, with the incorporation of plant residues and associated with spontaneous plants favored the diversity of functional groups.