Ken-ichiro Honda

Insect reactions to light and its applications to pest management

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.

Distribution and molecular characterization of distinct Asian populations of Bemisia tabaci (Hemiptera: Aleyrodidae) in Japan.

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.

Co-transmission of Tomato yellow leaf curl virus (TYLCV)-Mld and TYLCV-IL by the whitefly Bemisia tabaci

The ability of the whitefly Bemisia tabaci to transmit two strains of Tomato yellow leaf curl virus, the Israel and Mild strains, was studied after serial transfers of individual whiteflies that were viruliferous for both strains to tomato plants. After single whiteflies had successive acquisition feedings first on a single plant infected with one strain and then on a plant infected with the other strain, the single whiteflies later transmitted intermittently one, the other, or both strains to the test plants during serial transfers at 1-day intervals. Because both strains were found in the head, abdomen, and legs dissected from whiteflies during the retention period after the two successive acquisition feedings, both strains apparently circulate from midgut cells to salivary glands through the hemolymph.

Attraction of Leuroperna sera (Lepidoptera: Plutellidae) to a synthetic sex pheromone lure for Helicoverpa armigera (Lepidoptera: Noctuidae, Heliothinae)

Leuroperna sera (Meyrick, 1889) adults were specifically captured at sticky traps using a synthetic sex pheromone lure for Helicoverpa armigera (Hubner, [1808]) as an attractant. Among the components of the lure for H. armigera, (Z)-9-hexadecenal is likely to be a key component for the attraction of L. sera. The lure will be useful for forecasting the occurrence of L. sera.

Behavioral responses of insect pests attacking leaf vegetables under ultraviolet-absorbing plastic films with different wavelengths transmitted and ultraviolet-transmitting films

The movement of five leaf vegetable insect pests, Athalia rosae ruficornis, Phyllotreta striolata, Plutella xylostella, Chromatomyia horticola and Thrips tabaci were examined with an ultraviolet (UV)-transmitting plastic film and four UV-absorbing films, which blocked wavelengths below 340 nm, 360 nm, 370 nm or 380 nm. The insects were placed in an experimental box covered with the UV-transmitting film and the UV-absorbing film; their choice behaviors were observed. The numbers of A. rosae, P. striolata and T. tabaci distributing in the area under all the UV-absorbing films tested were smaller than those under the UV-transmitting films. Movement of P. exlostella and C. horticola into areas under films blocking UV wavelengths below 360 nm,370 nm and 380 nm was suppressed compared to that with the UV-transmitting films. From these findings, we would expect the five insect pests tested to avoid light conditions that do not contain UV wavelengths of 360 nm and less.