Leaf hairs influence searching efficiency and predation rate of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae)

Abstract

Abstract:The effect ofleafhairs on searching efficiency of adult female Phytoseiulus persimilis was investigated. For this purpose we used the ornamental crop Gerbera jamesonii and determined the predator's searching efficiency on three cultivars that differ largely in density of leaf hairs on the undersurface of the leaves. Walking speed of the mites was highest on the cultivar with the lowest leaf hair density. Walking activity, defined as the percentage of time spent walking, was not dependent on leaf hair density of the cultivars. At both prey densities tested, time until first predation increased with leaf hair density. Predation rate of adult female P. persimilis is affected by trichome density, especially when prey density is low. At prey densities of 1.3 and 2.5 T. urticae eggs/cm2, predation rate was inversely related to leaf hair density. At a prey density of 8.0 eggs/cm2 no significant effect of leaf hair density on predation rate was found. These negative effects on searching efficiency and predation success at low prey density of P. persimilis suggest that biological control of T. urticae on gerbera may be hampered by leaf hairs.

A Novel Disease Affecting the Predatory Mite Phytoseiulus persimilis (Acari, Phytoseiidae): 1. Symptoms in Adult Females

“…The walking speed found in the present study (about 0.17 cm/s) is higher than values found in other studies. In a comparable experimental set-up the highest mean walking speed found was 0.10 ± 0.030 cm/s on the Gerbera cultivar Bianca (Krips et al 1999). As leaf hairs have been shown to negatively influence the walking speed of P. persimilis (Krips et al 1999) a higher walking speed may be expected on Lima bean that does not carry leaf hairs whereas the Gerbera cultivar Bianca carries about 100 hairs per cm 2 .…”

“…In a comparable experimental set-up the highest mean walking speed found was 0.10 ± 0.030 cm/s on the Gerbera cultivar Bianca (Krips et al 1999). As leaf hairs have been shown to negatively influence the walking speed of P. persimilis (Krips et al 1999) a higher walking speed may be expected on Lima bean that does not carry leaf hairs whereas the Gerbera cultivar Bianca carries about 100 hairs per cm 2 . However, Sabelis (1981) found a walking speed of 0.12 ± 0.015 cm/s for starved predators on rose, which is also a plant without leaf hairs.…”

“…Spider mite eggs originating from the general rearing served as prey for the predatory mites. On each leaf disc 32 spider mite eggs were placed in 4 rows, thus creating an egg density of 8 eggs/cm 2 (see Krips et al 1999). One 7-9 days old mated female predator was placed on each leaf disc.…”

Eficiência do ácaro predador Phytoseiulus macropilis (Banks) (Acari:Phytoseiidae) no controle de Tetranychus urticae (Koch) (Acari: Tetranychidae) em tomateiro

“…No entanto, os tricomas de berinjela, embora não glandulares, parecem interferir significativamente no desempenho daqueles predadores. Kleijn et al (1997) e Krips et al (1999) também relataram menor velocidade de deslocamento de P.…”

“…Para a berinjela, por outro lado, o elemento desfavorável poderia, alternativamente ou ao mesmo tempo, ser físico, como sugerido pelo menor consumo de presas e menor oviposição do predador somente na ausência da teia. Este resultado sugere que a dificuldade de locomoção dos predadores nessa planta se deva à grande quantidade de tricomas, como sugerido por Krips et al (1999) para G. jamesonii.…”