To study seasonal population abundance of whitefly, Bemisia tabaci (Genn) on various cucurbit crops

The studies on seasonal population of whitefly on various cucurbit creepers in two seasons i.e. spring and summer were conducted. Indian squash, musk melon, ridge gourd were sown. All agronomical practices and use of fertilizer were employed whenever needed. No pesticide application was made throughout season. Whitefly adults were counted on leaf and nymphs were sampled by putting a metal frame of 2sq. cm on the under side of the leaves. The nymphs confined with in the metal ring were counted by the help of a magnifying glass. Twenty five leaves from each cucurbit field were examined for whitefly population. One leaf per creeper was randomly selected from various nodes of main-stem. Scouting was made early in the morning from 7:30 to onwards. Weekly observations were made in both the seasons. The results revealed that initial population 3.72 plus minus 0.76, 2.80 plus minus 0.43 and 3.48 plus minus 0.35 per leaf was recorded on muskmelon, Indian squash and ridge gourd respectively. Initially lesser number of whitefly per leaf was recorded on spring grown creepers than summer because after over wintering the whitefly started its activity at low level. The population of whitefly increased as time elapsed. The highest population 6.00 plus minus 0.85, 4.84 plus minus 0.64 and 4.28 plus minus 0.64 per leaf was recorded in 3rd week of March on musk melon, Indian squash and ridge gourd respectively. Less fluctuation in population was recorded during spring on all creepers. The over all mean indicated that musk melon harbored 4.62 plus minus 0.72 flies per leaf as compared to Indian squash (3.74 plus minus 0.59) and ridge gourd (3.21 plus minus 0.48). On summer grown creepers, whitefly appeared on all three cucurbits in seeding stage. During seedling stage the number of whitefly 5.36 plus minus 0.74, 4.24 plus minus 0.61, and 3.16 plus minus 0:05 per leaf was recorded on muskmelon, Indian squash and ridge gourd respectively. Maximum population 7.65 plus minus 1.07 per leaf on musk melon, 5.92 plus minus 0.93 on Indian squash and 4.84 plus minus 0.57 on ridge gourd was recorded in 1st week of June then reduced to 2.64 plus minus 0.62, 2.28 plus minus 0.48 and 1.80 plus minus 0.42 per on musk melon, Indian squash and ridge gourd respectively, in 3rd week of June. Whitefly population was remained non-significant during three weeks time that indicated that either population was migrated from adjacent fields or the fly was displaying its over tapping generations. Two peaks in population were recorded in summer grown creepers that also indicated the two discrete generations of whitefly on the creepers. Among these cucurbits musk melon was more preferable followed by Indian squash and ridge gourd. Analysis of variance showed significant difference between crops. LSD shows the same difference in the crops. It is concluded that whitefly appeared on musk melon, Indian squash and ridge gourd in spring as well as in summer season. Significant difference was recorded in the population on the creepers grown in both seasons. Two peaks in population were recorded in summer season and population remained less fluctuated in spring. Musk melon was the most preferred creeper in both the seasons.