Relationship between semi-arid landscapes and environmental factors on predator and pest composition within alfalfa systems

Alfalfa fields in western landscapes confront unique challenges seldom encountered in other ecological habitats. The vulnerability to drought stress, heightened by fluctuating seasonal temperatures, exposes crops to various pest species, including alfalfa weevils (Hypera postica) and multiple aphid species, resulting in significant crop losses for alfalfa producers. Alfalfa hosts a diverse community of predators that can aid in the suppression of pest populations. However, the success of these predators' hinges on environmental factors. During the growing season New Mexico can experience temperatures above 38C, < 6 cm of precipitation during summer months, and relative humidity as low as 6% during the growing season. Crop production in New Mexico is also unique in that there are few expansive monocultures and rather smaller parcels of alfalfa adjacent to diverse landscapes. Consequently, the landscape composition of the surrounding agricultural system can range from developed urban lands to semi-natural land. Each of these factors could substantially impact predator biodiversity, shaping their richness, abundance, developmental and behavioral patterns. A total of 24 alfalfa fields in three counties (Dona Ana, Valencia, and Eddy counties) were surveyed throughout New Mexico. Sweep and vacuum sampling was conducted across three 20 m transects per field to collection predatory and pest arthropods. Sampling occurred every other week from March to September. Environmental and landscape factors for each field were characterized to analyze their impact on predator species, abundance, and overall pest richness.