Cultural managemant of diamondback moth, Plutella xylostella (Linnaeus), on crucifers
Abstract
Overhead irrigation, nurse/trap cropping, and manipulation of macronutrient soil fertility were investigated for diamondback moth (DBM), Plutella xylostella (L.), management on crucifers. The use of overhead irrigation, as needed, on head cabbage reduced DBM infestation an average of 51.9% compared with drip irrigation. The application of daily, intermittent sprinkling between 8:00 p.m. and 11:30 p.m. reduced DBM infestation 85.9%. The 'Sylvasprings' variety of watercress was used as a nurse crop for DBM, in Hawaii, and interplanted with the 'Florida' variety of watercress as the main crop. In 1992 and 1993, 14-fold and 8-fold more DBM were found, respectively, in 'Sylvasprings' watercress. Parasitoid to host ratios for the DBM larval parasitoid Cotesia plutellae (Kurdjumov) were more favorable in the 'Florida' variety in both years. Watercress quality was significantly better in the 'Florida' variety. Tissue calcium (Ca) levels were higher in 'Sylvasprings' watercress suggesting some mechanism by which preference is expressed. In Indiana, 12 host plants were screened for preference by DBM in 1992. Head cabbage, broccoli, cauliflower, pak choy, canola, and collards were the most preferred. Order of preference was head cabbage $>$ canola $>$ pak choy $\ge$ collards $>$ cauliflower $>$ broccoli. Broccoli was selected as a main crop and tested against head cabbage, canola, pak choy, and collards for preference. Significantly greater DBM oviposition occurred on broccoli paired with collards in the greenhouse in 1993. Significantly lower percentage of DBM were recovered on broccoli paired with canola in 1993 field testing. Numbers of DBM were significantly greater on canola while tissue Ca levels were significantly less. Manipulation of nitrogen (N), phosphate $\rm (P\sb2O\sb5),$ and potash $\rm (K\sb2O)$ rates in the greenhouse and in the field in 1992 revealed no relationship between fertilizer treatment and DBM infestation. Tissue nutrient analysis showed a positive correlation between accumulated tissue sulfur (S) and number of DBM. Manipulation of N rates in the greenhouse in 1993 also showed no effect of N fertilization on DBM. Foliar application of 0, 0.01, 0.1, 1, and 10% S on greenhouse cabbage in 1994 indicated that DBM oviposition declined as S dosage increased.
Degree
Ph.D.
Advisors
Foster, Purdue University.
Subject Area
Entomology
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