| Bemisia tabaci (Gennadius) B-biotype (B. tabaci in short in this text) is a devastating pest of vegetables, ornamentals and other agronomic crops throughout the tropical and subtropical regions of the world. As an alien invasive pest, B. tabaci has caused a serious economic loss of crop production in China since 2000. Conventionally, chemical control is the main method to control B. tabaci. Besides environment pollution and pesticides residue problems, the use of insecticides regularly has resulted into development of resistance in insect pests. The urgent need is to developed an economic, safe and effective method to control B. tabaci. So the population dynamics on cotton, soybean, peanut and piemarker (Abutilon theophrasti Medic) was surveyed in field in northern China, and the control effects of using piemarker as trap crop, combined with auxilliary chemical control was studied in the integrated management of B. tabaci. The taxis behavior of B. tabaci to piemarker and other host plants and its physical and chemical mechanisms were also studied. The effects of color, odor, and the physilological, morphological and biochemical characters of the host plants to the behavior of host selection of B. tabaci were reported in this paper. The main results are summarized as follows:(1) The population of B. tabaci increased with the growing stage of hosts and reached to the peak in the middle of August, then declined gradually later on during successive years, 2004-2005. The population dynamics of egg, nymph and adult of B. tabaci on piemarker were similar to those on cotton, soybean, and peanut, while their densities on the former were significantly higher than those on the latter crops. The feeding behavior of B. tabaci on piemarker, cotton, cabbage, and tobacco was recorded by EPG technology. The results showed that B. tabaci spent more time (> 83.7%) for feeding in phloem of piemarker leaves, and the average duration of stylet in phloem was more than 20.2 minutes. The number and time for finding and probing food on piemarker are less than that on cotton, cabbage, and tobacco. The developmental rate and survival rate of B. tabaci were significantly high than those on cotton, tobacco, cucumber and cabbage. So piemarker was proved to be favorable for B. tabaci feeding and ovipositting.(2) B. tabaci preference to piemarker may be attributed to the conducive physilological, morphological and biochemical characters of piemarker. B. tabaci was strongly attracted to a surface with yellow reflecting in the range of 500-700 nm. The surface reflecting rate of piemarker leaves was significantly higher than that of cotton, soybean and peanut, which indicated that piemarker can be attracted first by B. tabaci among all the host plants. Middle hair density of piemarker leaves harboured high populations of B. tabaci. The relative incidence of B. tabaci corresponded with the trend of the pH curve, indicating partiality towards higher pH values. The pH levels of the piemarker leaves ranged at 5.8-6.2 during the developing stages which was found to be optimal to B. tabaci. The content of carbohydrates and amino acids were not different significantly among the phloem sap of piemarker, cotton, cucumber, tobacco and cabbage plants.(3) The role of volatile cues from five species of host plants in the host-selection behavior of B. tabaci was investigated by Y-tube olfactometer. The result indicated 30 percent of B. tabaci adults have no response to the odor of host plants, and more than 50 percent of adults shows the strongest host preference to piemarker, cotton, tobacco, cucumber and cabbage. There was no significant difference on the attractiveness of adults among piemarker, cotton, tobacco, cucumber and cabbage.Scanning electron microscopy was used for illustrating the detail structure of the antennae of B. tabaci. Five types of sensilla were found on the antennae, such as microtrichia, chaetica, campaniform, basiconic, and coeloconic sensilla. The ultrastructure of coelonic sensilla suggests primarily a chemosensory function, and just the basiconic sensillas have an ultrastructure typical of olfactory sensilla and probably have a primary olfactory function.(4) Piemarker as trap plants for B. tabaci in cotton and soybean crops was investigated during 2004-2005 in Langfang, Hebei province. There was a strong attraction of the piemarker plants to the whitefly, with significant differences among the treatment planted on different dates. The whiteflies were first found on the early planting piemarker with an attractive rate of 85.2% in early period of cotton/soybean growth, while the piemarker plants sown in middle and late periods presented high trapping efficiencies to the pest (93.3% and 95.4%) in middle and late season, respectively. Piemarker as trap plants in cotton and soybean field can play an important role in the integrated management of B. tabaci.Trap cropping was presented a new methods to the integrated pest management (IPM) strategy. B. tabaci is a polyphagous herbivore, it locates to the host plants in line with certain reflective color/light or phytochemicals they produced. To study the mechanism of taxis behaviors of B. tabaci by applying chemical and behavioral methods is most important for illustrating the outbreak factors and devising IPM tactics against this pest. Piemarker as trap crop for B. tabaci, including crop diversity, sequential planting, combined with chemical control served as a major contributor to the integrated management of B. tabaci. Trap cropping as an IPM tool of B. tabaci can relieve the potential negative effects of pesticides on human health and the environment, pesticide resistance, and assuring economic and safe production of agricultural crops.
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