Comparison of Two Methods of Infesting Cotton Bolls with Pink Bollworm (Lepidoptera: Gelechiidae) Eggs

A technique was developed to infest cotton, Gossypium hirsutum L., bolls artificially with eggs of pink boll worm, Pectinophora gossypiella (Saunders). The technique is applicable to both field and greenhouse experimentation. Pink bollworm eggs are suspended in a solution of xanthan gum prepared by dissolving the powdered gum in distilled water. This viscous solution allowed eggs to remain suspended, yet was fluid enough to distribute eggs evenly in the liquid. Cotton bolls of known age were inoculated with a droplet of the suspension with the use of an automatic repeating pipette. After the droplet dried, the eggs adhered to the surface of the boll and larvae emerged freely. Seed damage caused by PBW was not significantly different when bolls were infested by this method compared with a method in which 1-cm2 egg papers were placed on the bolls under the calyx, nor was seed damage significantly different than in naturally infested bolls. Time required to infest bolls using the egg suspension method was significantly less than that required to infest bolls using the egg paper method.