Insects are able to see ultraviolet (UV) radiation. Nocturnal insects are often attracted to light sources that emit large amounts of UV radiation, and devices that exploit this behavior, such as light traps for forecasting pest outbreaks, and electric insect killers, have been developed. Some diurnal species are attracted to yellow; yellow pan traps are used for conducting surveys for pest outbreaks and yellow sticky plates are used for pest control. Lamps that give off yellow illumination have been used effectively to control the activity of nocturnal moths and thus reduce damage to fruit, vegetables, and flowers. Covering cultivation facilities with film that filters out near-UV radiation reduces the invasion of pests such as whiteflies and thrips into the facilities, thus reducing damage. Reflective material placed on cultivated land can control the approach of flying insects such as aphids. Future development and use of new light sources such as light-emitting diodes is anticipated for promoting integrated pest management.

Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) B-and Q-biotypes are exotic insects in Japan and are consequently regarded as insect pests in agricultural fields. Using B-and Q-biotypes, we investigated the hatching rate, survival rate during the larval stage and the total development period from egg to adult. Whiteflies were allowed to lay eggs on several host plants: cabbage, Brassica oleracea var. capitata; cucumber, Cucumis sativus L.; tomato, Solanum lycopersicum L.; eggplant, Solanum melongena L.; bell pepper, Capsicum annuum cv. grossum; and five cultivars of kidney bean, Phaseolus vulgaris (cvs. Kentucky101, Nagauzura, Morocco, Satsukimidori and Honkintoki), and the effects on the above traits were evaluated. Clear differences between the two biotypes were detected. A particularly important difference was that the B-biotype successfully developed to adults on only one of five cultivars of kidney bean, whereas the Q-biotype was able to utilize all the test plants as hosts regardless of the cultivar. This finding suggests that the determination of host plants in B. tabaci is greatly influenced by not only plant species but also by cultivar. In addition, there is a high possibility that the Q-biotype has the ability to adapt to a wider range of plant species and cultivars compared with the B-biotype.

Bemisia tabaci (Gennadius) is considered to be the most economically important pest insect worldwide. The invasive variant, the Q biotype of B. tabaci was first identified in 2004, and has caused significant crop yield losses in Japan. The distribution and molecular characterization of the different biotypes of B. tabaci in Japan have been little investigated. In this study, B. tabaci populations were sampled from the Japanese Archipelago, the Amami Archipelago and the Ryukyu Islands between 2004 and 2008, and the nucleotide sequences of their mitochondrial cytochrome oxidase I genes were determined. Bayesian phylogenetic relationship analysis provided the first molecular evidence that the indigenous Japanese populations could be separated into four distinct genetic groups. One major native population from the Japanese Archipelago, given the genetic group name Lonicera japonica, was separated into an independent group, distinct from the other genetic groups. The second major population, the Nauru biotype in the Asia II genetic group, was identified in the Amami Archipelago and the Ryukyu Islands. Two distinct minor genetic groups, the Asia I and the China, were also identified. One invasive B‐related population belonging to the Mediterranean/Asia Minor/Africa genetic group has been identified in Honshu. All lineages generated by the phylogenetic analyses were supported by high posterior probabilities. These distinct indigenous B. tabaci populations developed in Japan under geographical and/or biological isolation, prior to recent invasions of the B and Q biotypes.

We studied the presence of a potential transmission barrier that blocks Tomato yellow leaf curl virus in the nonvector greenhouse whitefly, Trialeurodes vaporariorum. Because T. vaporariorum can ingest and retain the virus after acquisition feeding on an infected plant, comparable to the vector whitefly Bemisia tabaci, circumstance evidence suggested that a transmission barrier presents at location(s) where the virus moves from the digestive tract lumen to the hemolymph. To provide direct evidence for the site of a transmission barrier in the nonvector insect, we compared the accumulation levels and localization of the virus between the two species of whiteflies. Quantitative real-time and conventional PCR analysis showed that accumulation of the virus during acquisition feeding and retention after a short acquisition period were indistinguishable between the two species, but the circulation of the virus within the whiteflies differed significantly between the species. In an immunofluorescence analysis using an antibody specific to the coat protein of the virus, the virus was restricted to the luminal surface of the midgut epithelial cells and did not enter their cytoplasm or that of the salivary glands in T. vaporariorum. In contrast, the virus was localized within the cytoplasm of the midgut epithelial cells and in the paired salivary glands of B. tabaci adults. This direct evidence shows that a selective transmission barrier at the luminal membrane surface of midgut epithelial cells in the nonvector whitefly blocks entrance of the virus into the midgut epithelial cells, resulting in incompetence as a vector of the virus.

The silverleaf whitefly, Bemisia argentifolii Bellows et Perring (Bellows et al., 1994), also known as B-biotype of B. tabaci (Gennadius) (Byrne and Miller, 1990), has become one of the most serious agricultural pests in the world. This whitefly is polyphagous and infests a broad range of crops, including eggplant, cucumber, squash, tomato and sweet potato . Damage by B. argentifolii consists of direct feeding damage, deposition of large quantities of honeydew, plant physiological disorders, such as squash silverleaf disorder in pumpkin and irregular ripening of tomato fruit, and transmission of several plant viruses (Matsui, 1995).In Japan, B. argentifolii was first found to infest poinsettia (Ohto, 1990) and since has infested many plants, including cucumber, eggplant, sweet pepper and tomato. The biology of B. argentifolii has been studied extensively (Bethke et al., 1991;Enkegaard, 1993;Simmons, 1994;Wagner, 1995;Tsai and Wang, 1996;Wang and Tsai, 1996;Yee and Toscano, 1996;Nava-Camberos et al., 2001), although, with the exception of a study by Tsueda and Tsuchida (1998), the biology of the Japanese B. argentifolii population has not been investigated.To develop a successful integrated pest management (IPM) program for its host crops, it is critical to understand the life-history parameters of B. ar- Appl. Entomol. Zool. 42 (1): 63-70 (2007)

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Six species of legume or cereal-feeding aphids, Acyrthosiphon pisum, Aphis craccivora, Megoura crassicauda, Rhopalosiphum maidis, Rhopalosiphum padi and Sitobion akebiae (Hemiptera: Aphididae), were tested as candidates for alternative hosts of Aphidius gifuensis (Hymenoptera: Braconidae), an indigenous natural enemy attacking vegetable pest aphids Aulacorthum solani and Myzus persicae (Hemiptera: Aphididae). A. pisum, R. maidis and S. akebiae were accepted by A. gifuensis. S. akebiae showed the most successful parasitism by A. gifuensis among the six aphid species tested, with a mummification rate of 71.7% and emergence rate of 96.7%. No parasitism was observed on R. padi, an alternative host available in the banker-plant system with an exotic parasitic wasp, Aphidius colemani (Hymenoptera: Braconidae). A. gifuensis females reared on S. akebiae had the same developmental period and body size as those reared on M. persicae, with no significant differences. They also demonstrated successful parasitic performance in A. solani and M. persicae. These results suggest that S. akebiae should be a promising alternative host for use in a banker-plant system with A. gifuensis.

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