Increasing habitat complexity through cover cropping has been proposed as a tactic to reduce herbivore colonization and encourage natural enemies in cropping systems. To test the supposition that cover crops can be used to alter arthropod communities, we compared arthropod communities on cucumber (Cucumis sativus L.; Cucurbitaceae) interplanted with a red clover (Trifolium pratense L.; Fabaceae) living mulch and grown as a monoculture. In 2016 and 2017, visual surveys and yellow sticky card traps were used to estimate numbers of arthropod natural enemies and herbivores in each treatment. Among herbivores, striped cucumber beetles [Acalymma vittatum (Fabricius, 1775); Coleoptera: Chrysomelidae] and melon aphids (Aphis gossypii Glover, 1877; Hemiptera: Aphididae) had lower densities in the presence of red clover. However, populations of spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber, 1947; Coleoptera: Chrysomelidae) had a variable response to red clover. Sticky card captures of natural enemies, including bigeyed bugs (Geocoris spp. Fallén; Hemiptera: Geocoridae), minute pirate bugs (Orius spp. Wolff; Hemiptera: Anthocoridae), and lady beetles (Coleoptera: Coccinellidae), were generally greater in cucumber interplanted with red clover than monoculture. Overall, cucumber yield did not differ between treatments. Findings from this study lend support to the hypothesis that greater habitat complexity can reduce herbivore densities.

Agricultural drainage ditches are artificial structures used to optimize soil hydrology for crop production and secondarily have been co-opted as a t

Cover cropping has long been used as a method of reducing soil erosion, increasing soil quality, and suppressing weeds. However, the effects of cover crops in local farming systems are varied and can be affected by timing and method of termination. Field experiments were conducted at two sites in Maryland, USA during the 2013 and 2014 growing seasons to examine how varying the date and method of terminating a barley (Hordeum vulgare) cover crop affects the arthropod communities in succeeding no-till soybean (Glycine max). Experimental treatments included early-kill with pre- and post-emergent herbicides (EK), late-kill with pre- and post-emergent herbicides (LK), late-kill with a flail mower and pre-emergent herbicide (FM), and a fallow/bare-ground check with pre- and post-emergent herbicides (BG). Terminating barley late, just prior to soybean planting, resulted in significantly greater biomass accumulation in LK and FM than EK. However, method and timing of termination had no effect on the community of pest and beneficial arthropods in the soybean canopy. Results from this experiment suggest that terminating the cover crop early or late (just prior to crop planting) or using a mower or post-emergent herbicide will result in a similar community of arthropods within the soybean canopy.

Soil tillage is generally recognized as having a negative effect on soil health and weed seed predators. Recent advancements in conservation tillage practices allow for further comparison of how different levels of soil disturbances could influence soil food web communities. Field trials were conducted in 2017 and 2018 at two different sites to measure the effects of four cover crop termination treatments: conventional till (CT), no-till (NT), strip-till following roller-crimping (ST-RC), and strip-till with a living mulch between crop rows (ST-LM) on soil health using nematode community indices as soil health bioindicators. Following cover crop termination, the soil was monitored in the subsequent bell pepper (Capsicum annuum) crop over three sampling dates (June, August, and October). In the ST-RC treatment plots, soil nutrients were enriched (increased Enrichment Index, EI) and the soil food web structure was improved (higher Structure Index, SI) by the mid-season of the 2017 trial. In the 2018 trial, the ST-RC treatment enhanced fungal decomposition pathways (fungivore/fungivore + bacterivore ratio) throughout the bell pepper crop cycle and enhanced bacterial decomposition (abundance of bacterivorous nematodes) by the end of the cropping cycle compared to the no-till treatment, suggesting that the ST-RC treatment can further improve soil health conditions achieved by the NT treatment. Scatter plots of sampling points revealed that the treatments CT and NT had very distinct nematode-weed community assemblages in both trials, with the ST-RC and ST-LM treatments distributed closely with the NT treatment. Multivariate analysis among soil health bioindicators, weed pressure and weed seed predation explained 76.4 and 55.7% of the variance in the 2017 and 2018 trials, respectively. Weed pressure was consistently negatively related to (1) the SI, indicating soil disturbance would lead to more weed pressure; (2) the EI, indicating soil with higher weed pressure was linked to poor soil nutrient cycling, (3) cover crop residues left in the field from conservation tillage, or (4) how well the living mulch of red clover covered the ground. This study did not show that weed seed predation would lead to lower weed pressure but weed seed predation increased as weed biomass increased.