A Rapid Field Technique for Infesting Cotton Plants with Pink Boll worm (Lepidoptera: Gelechiidae) Eggs1

Abstract

A rapid method is described for spraying eggs of pink boll worm (PBW), Pectinophora gossypiella (Saunders), on plants of cotton, Gassypium hirsutum L., to evaluate the plants for resistance to the insect. Pink boll worm eggs were collected from the USDARS rearing facility at Phoenix, Ariz., and suspended in a 0.05% solution of gum xanthan in distilled water. After preliminary experimentation, we used a ratio of 1 egg to 1,250 parts solution (14.4 eggs per ml of solution). The solution was poured into a polypropylene bottle and sprayed on cotton plants in the field with the use of a spray wand (an estimated 630 eggs in 44 ml solution per meter of row). A constant air pressure was maintained with the use of an oxygen tank fitted with a compressed air regulator and a line pressure gauge. This method required 2.5 s per boll per person compared with 21.3 s per boll per person for boll infestation by the use of an automatic repeating pipette. Using the new method, we evaluated 99 cotton germ plasm lines and found 19 that sustained significantly less seed damage caused by PBW than the resistant control line, AET-5.