Life-history traits of the Kanzawa spider mite Tetranychus kanzawai (Acari: Tetranychidae).

Abstract

Performance of phytophagous insects and spider mites on different host plants is influenced by the nutritional value and defenses of the plants; important factors include secondary chemicals, leaf nutrition, leaf age and leaf surface structure (Gerson and Aronowitz, 1980; Jaenike, 1990;Wilson, 1994;Van Impe and Hance, 1993; Krips et al., 1998;Agrawal, 2000). When spider mites infest chemically defended or poor-quality plants, their intrinsic rate of natural increase (r m ) should be low (Gould, 1979;Fry, 1989;Bruin et al., 1992; Krips et al., 1998;Agrawal, 2000). In the two-spotted spider mite, Tetranychus urticae Koch, for example, the initial r m -value (0.088/day) on a resistant gerbera cultivar was increased to 0.208/day after they had been reared on this cultivar for five months, but it was still substantially lower than the r m -value on a susceptible cultivar (0.242/day; Krips et al., 1998). Adaptation of mites to unsuitable host plants or novel host plants that are of poor quality is often accompanied by a reduction in fitness, even if the mites are polyphagous.The Kanzawa spider mite, Tetranychus kanzawai Kishida, is an important pest threatening many agricultural crops and ornamental plants in Far Eastern areas. The broad host range of T. kanzawai is due to the presence of host races: the ability to develop on tea, Camellia sinensis L., and hydrangea, Hydrangea macrophylla (Thunb.), containing harmful secondary chemicals for spider mites is regulated by a single dominant gene, 'T' and 'H', respectively (Gomi and Gotoh, 1996, 1997). These genes are thought to be involved in the chemical detoxification of harmful secondary chemicals, such as tannin in tea and hydrangenol in hydrangea (Dowd et al., 1983;Ujihara et al., 1995; Gomi and Gotoh, 1997; Gotoh and Gomi, 2000). Recently, T. parakanzawai Ehara, a sibling species of T. kanzawai, is found on the kudzu vine, Pueraria lobata (Willd.) (Ehara, 1999). The host range of this species overlaps considerably with that of T. kanzawai (Gomi and Gotoh, 1996), but T. parakanzawai never develops on tea or on hydrangea (Gotoh et al., 1999). For effective management of T. kanzawai, we need to know its ecological traits (population growth rate, etc.) on economically important plants. Most of the data obtained thus far are on easily grown host plants such as bean, while few are on crops such as grape (Kondo et al., 1987). The difference of the r m -values among the infested plants affects the actual rates of population growth, that is, how rapid a population increases on AbstractLife-history traits of the Kanzawa spider mite, Tetranychus kanzawai, were assessed and compared with those of the closely related species, T. parakanzawai. This was done by determining the intrinsic rates of natural increase, r m , of three strains of T. kanzawai and one strain of T. parakanzawai, on leaf discs from each of the four host plants (collected plants) as well as one of suitable hosts for T. kanzawai, mulberry. The r m -values of the three T. kanzawai strains varied largely f...

Effect of soybean cultivar on life history parameters of Tetranychus urticae Koch (Acari: Tetranychidae)

“…Then fecundity of females was checked and laid eggs were counted and removed daily from each leaf disc. This experiment was continued until all experimental females died (Gotoh and Gomi 2003). We evaluated fecundity of 16 two-spotted mite females for each cultivar.…”

Species composition and seasonal changes of spider mite density on a leguminous plant Pueraria lobata

“…Of these species, four (T. kanzawai, T. ludeni, T. piercei and T. urticae) are known to be pests of agricultural crops (Bolland et al, 1998). T. parakanzawai is polyphagous (Gomi and Gotoh, 1996) and has a high r m value (0.276 at 25°C; Species composition and seasonal changes of spider mite density on a leguminous plant Pueraria lobata Gotoh and Gomi, 2003). T. pueraricola is also polyphagous but prefers leguminous plants (Gotoh et al, 2004a), and has a high r m value (0.299 at 25°C; Gotoh et al, 2004b); therefore, T. parakanzawai and T. pueraricola have potential as pests when they invade a crop field.…”

Control of silverleaf whitefly, cotton aphid and kanzawa spider mite with oil and extracts from seeds of sugar apple

“…During the screening tests, oil pressed out of seeds of sugar apple (Annona squamosa) was found to be very effective in causing mortality of silverleaf whitefly nymphs, while its aqueous extract was ineffective and the ethanolic extract was only slightly effective. Since the cotton aphid, Aphis gossypii Glover (Conway et al 2003), and the Kanzawa spider mite, Tetranychus kanzawai Kishida (Gotoh & Gomi 2003), are also important pests of many agricultural crops and pesticides have been frequently applied for their control, they were also tested. It was found that oil from sugar apple seeds was also very effective in reducing the survival rate of these two pests.…”