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Intensive surveys conducted at Samaru and its environs in the northern Guinea Savanna of Nigeria between October 2000 and September 2002, indicated that Bemisia tabaci (Genn.) infests forty two (thirty three cultivated and seven wild) species of plants. Twenty nine of the plants were found in upland, two in the lowland and eleven in both upland and lowland (fadama) areas. Heavily infested plants were distorted, chlorotic and stunted. Symptoms of virus infection were associated with some of the infested plants. This is the first comprehensive report of hosts of B. tabaci in Nigeria.
A survey in four distant locations: Anuradhapura, Madampe, Sri Jayewardenapura and Uda Walawe of Sri Lanka to identify the whitefly species related to cassava revealed two species, namely Bemisia tabaci (Gennadius) and Alerodicus dispersus (Russell). The species B. tabaci was recorded in all four surveyed locations, while A. dispersus was collected only from the first three locations. The results of the study on the pest life cycle under the laboratory conditions showed that, B. tabaci and A. dispersus passed through four nymphal instars before the adult stage. The mean duration values of these stages were 7.2, 7.5, 4.7, 5.6 and 8.5, 6, 9, 9 days respectively for the two species. The total duration of the life cycle of B. tabaci ranged from 22-57 days at the temperature of 29±2°C with a mean of 37.5 while that of A. dispersus was 27-68 days with a mean of 48 respectively (at 28±2°C). The damage to crop plants caused by two whitefly species is discussed with a special emphasis on their ability to transmit viral diseases.
Samples of whiteflies were collected from Dendranthema spp. in major growing areas of Tanzania. The insects were transferred onto test plants to confirm host specificity. Infested with insects, test plants were then protected with polyethylene bags. Samples of whiteflies from infested plants were taken at 10 day intervals post-infestation (dpi), 28 dpi and 35 dpi, for behavioural studies. At 10 dpi eggs were seen as oval bodies while at 28 dpi crawling bodies and newly emerged adults were observed, leaving behind characteristic shiny hollow cases. At 35 dpi, all the stages of development were seen. The features observed are typical of Bemisia argentifolii and the area is endangered by the occurrence and spread of viruses transmitted by this species. This identification, which is an integral part of pest surveillance, initiates a study of the viruses and will lead to pest records for regulatory purposes. The international scientific and trading community is assured that the report reflects the real situation. The pest is thought to be present in the reported areas only and the pest status is actionable and under surveillance.
Asterobemisia paveli (ZAHRADNIK, 1961) has been found for the first time in southern Poland. Some information about its morphology, distribution, host plants and life cycle have been given the first time.
The effects of application of an artificial honeydew mixture of glucose, fructose and trehalose (GFT), honey and Bemisia tabaci nymph-extract as kairomonal sources in enhancing the foraging efficiency and performance of Eretmocerus sp. near furuhashii on cucumber plants were studied. Experiments were conducted in small greenhouses (4x3*3 m) using life table methods. Life table data indicated that the total mortality in B. tabaci immature cohorts in all treatments was in the order of fourth instar > first instar > second = third > egg > pupa cohorts. The tested kairomonal materials had a significant effect on the rate of parasitism (p > 0.0415) with 13.23, 9.04 and 10.54% higher than that of control in artificial honeydew of GFT, nymph-extract and honey treatments, respectively. B. tabaci egg/adult survival ratio was also significantly affected (p > 0.0001) by the tested kairomonal sources being lowest (22.91%) in nymph-extract treatment. Moreover, the tested kairomonal materials arrested significantly more parasitoids to colonize the treated plants comparing to control. Apparently, the tested materials were significantly effective in attracting the parasitoids up to 3 days after applications then significant difference was not found between treatments.
The paper summarizes both published and new data on the distribution of whiteflies in Poland's national parks. Together 10 species of Aleyrodidae were recorded for the first time from the area of 9 parks.
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