MANUFACTURE AND USE OF A TRAP TO ASSESS HELIOTHIS VIRESCENS AND HELICOVERPA ZEA (LEPIDOPTERA: NOCTUIDAE) ADULT EMERGENCE

Abstract

Sampling arthropods in the soil is difficult and time consuming. Additionally, sampling methods can disturb much of the soil and plants, altering the outcome or the site for further evaluations. Placing an emergence trap in the field can allow accurate assessment of population numbers of different arthropod taxa, but its potential effect needs to be investigated. The basic manufacturing of a light weight, relatively inexpensive, weather-resistant conical trap is described here. Although several types of traps have been utilized in the past to record the emergence of Heliothis virescens L. and Helicouerpa zea (Boddie) moths from agricultural fields (Raulston et al. 1979, 1990; Hartstack et al. 1982; Lopez et al. 1984; Rummel et al. 1986; Laster et al. 1987; Bell & Hayes 1994), these reports lack detailed information of the materials, dimensions, and method of construction to accurately manufacture them. Also, the potential effect of the trap on the emergence of H. virescens and/or H. zea adults was not assessed in those studies. The trap described in this report is similar in construction to those described in Hartstack et al. (1979). It is constructed from a 4.26-m mild steel hot roll (0.60 cm = '/4-inch diameter) that is bent to create a 1.35-m diameter circle. The circle ends are welded together. Four 0.91-m straight pieces of the same material were welded at 1.06-m intervals along the circumference of the circle at ca. 420 angle relative to a horizontal plane forming a conical structure. The arms were welded to the base perimeter of a 5.0-cm long (2.0-cm internal diameter, 2.5-cm external diameter) metal pipe (Fig. 1). A coated fiberglass screen (2.03-m diameter circle with an 85-degree wedge cutout) was used to cover the structure. The fiberglass screen was secured with 50 c-rings (Stanley-Bostitch? 16 gauge, 40 around the base and 10 on the arm joining the ends of the net). The top of the trap was provisioned with a 3.65-L plastic jar (Consolidated Plastic Company, Inc. part number 41342LL) placed upside down. A 2.5-cm diameter hole was drilled in the center of the 8.5-cm diameter cap to screw the collection jar to the metal structure. Six 0.2-cm holes were also drilled around the perimeter of the cap to allow for water Jjar