Management of Western Bean Cutworm (Striacosta albicosta) in Western Nebraska

The western bean cutworm, Striacosta albicosta (WBC), is a major pest of corn and dry beans in the North American corn belt. In dry edible bean, WBC feeding damage can reduce yield and grade. This study\u27s overall goal is to understand better the effectiveness of pest management options and the perceptions surrounding them. Inundative biological control was investigated by releasing Trichogramma ostriniae into western Nebraska corn and dry bean fields. Dispersal and parasitism were monitored with yellow sticky cards and sentinel egg masses (Ostrinia nubilalis, S. albicosta, and Ephestia kuehniella) at 36 locations in each field surrounding a central release point. T. ostriniae was able to disperse rapidly into the field. However, parasitism was low, possibly indicating a lack of suitability for semi-arid western Nebraska. The possibility of distributing Trichogramma via pesticide tank mix was investigated in the laboratory. T. ostriniae pupae were immersed in field-relevant concentrations of select herbicides, fungicides, and adjuvants. Host eggs were observed for emergence holes ten days after removal from the solutions. Using an herbicide tank mix for dispersing Trichogramma warrants further study since many treatments did not reduce emergence. A dry bean-winter wheat relay was investigated to assess the effect on conservation biological control. The relay treatment had lower WBC feeding damage than the conventional dry edible bean. However, the yield was lower in the relay. The effectiveness of four pheromone trap types (milk jug, green bucket, electric trap, and camera trap) was assessed for monitoring WBC populations. The green bucket trap tended to catch more moths than the other traps. Unfortunately, there was little correlation between the number of moths caught and feeding damage. Stakeholder concerns, perceptions, and practices were assessed with an online survey and a series of focus groups. The survey provided quantitative data, such as the average WBC feeding injury received by growers. An important finding is that direct harvest may reduce the risk of WBC feeding

Assessing the toxicity of selected pesticides to\u3ci\u3e Trichogramma ostriniae\u3c/i\u3e (Hymenoptera: Trichogrammatidae) pupae as a first step in the development of a potential novel deployment programme

Trichogramma spp. have been used or have been proposed for use in biological control programmes of lepidopteran pests, including the European corn borer, Ostrinia nubilalis, the cotton bollworm, Helicoverpa armigera, and the spruce budworm, Choristoneura fumiferana. Releases are typically made by placing cards with parasitised eggs at set points in the field. However, this method can be cost-prohibitive due to its laborious nature. As a result, labour-saving mechanised release programmes have been developed, including distribution by spray equipment. However, few have investigated applying Trichogramma with a standard pesticide application (i.e. ‘tank mix’). As a first step to ascertain the feasibility of such a system, we observed the effect of immersion of T. ostriniae pupae in field-relevant concentrations of eight herbicides (bentazon, clethodim, fomesafen, quizalofop, Glacial acetic acid, glyphosate, imazamox, imazethapyr), three fungicides (Copper Hydroxide, flutriafol, and penthiopyrad), one insecticide (K+ salt of fatty acid), and five adjuvants (Ammonium Sulfate, Crop Oil Concentrate, Methylated seed oil, Non-ionic surfactant, and Urea-Ammonium Nitrate) on the emergence of T. ostriniae adults. The herbicides GAA and clethodim; the fungicides copper hydroxide, flutriafol, and penthiopyrad; and the adjuvants COC, MSO, and NIS all reduced T. ostriniae emergence compared to a water control. No emergence was observed with exposure to quizalofop, GAA, or K+ salt of fatty acid treatments. Other treatments did not affect emergence compared to water. Thus, deploying Trichogramma with a standard pesticide application may be a feasible labour-saving distribution method that warrants further investigation