INFLUENCE OF ECOLOGICAL FACTORS ON THE FORMATION OF WHITEFLY (BEMISIA TABACI GENN.) POPULATIONS

Abstract

The present study investigated the influence of ecological factors on the formation and development of whitefly populations belonging to the family Aleyrodidae, particularly greenhouse whitefly (Trialeurodes vaporariorum West.) and cotton whitefly (Bemisia tabaci Genn.), in vegetable and melon crop agrobiocenoses. The research focused on determining the effects of air temperature, relative humidity, and host plant species on pest population density under open-field conditions. Field experiments were conducted on several economically important crops, including cucumber (Cucumis sativus L.), melon (Cucumis melo L.), pumpkin (Cucurbita pepo L.), watermelon (Citrullus lanatus L.), tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), sweet pepper (Capsicum annuum L.), cabbage (Brassica oleracea L.), and carrot (Daucus carota L.). Entomological and ecological observation methods were applied during the study. Environmental parameters, including air temperature and relative humidity, were continuously monitored throughout the vegetation period. During the experiments, air temperature ranged from +22.4°C to 44.6°C, while relative humidity varied between 32% and 67%.

The obtained results demonstrated that ecological conditions and host plant characteristics significantly affected whitefly population density. The highest infestation levels were recorded on melon crops, where the average population density reached 84.8 individuals per leaf. High population density was also observed on pumpkin (74.7 individuals/leaf), cucumber (72.2 individuals/leaf), and eggplant (Solanum melongena L.) with 70.5 individuals per leaf. Moderate infestation levels were detected on sweet pepper (52.2 individuals/leaf), watermelon (48.6 individuals/leaf), and cabbage (48.3 individuals/leaf). The lowest infestation level among the investigated crops was recorded on tomato plants, where the average density reached 41.4 individuals per leaf. The study revealed that cucurbit crops create highly favorable ecological and nutritional conditions for whitefly development and reproduction. Increased relative humidity and moderate temperatures promoted population growth and accelerated pest development. Differences in infestation levels among crops were associated with plant biological characteristics, leaf morphology, nutritional composition, and microclimatic conditions within the agrobiocenosis.

The results indicate that ecological regulation methods may play an important role in integrated whitefly management. Proper crop placement, optimization of irrigation regimes, maintenance of balanced humidity conditions, and the cultivation of relatively resistant crops may contribute to reducing pest population density without excessive application of chemical pesticides. The findings provide valuable scientific information on the ecological features of whitefly population dynamics and may serve as a basis for developing environmentally safe and sustainable pest management systems in vegetable and melon crop production.