Intrinsic rate of population increase of the spider mite Tetranychus urticae on the ornamental crop gerbera: intraspecific variation in host plant and herbivore

Abstract

Eight cultivars of the ornamental crop Gerbera jamesonii Bolus (Asteraceae) were compared in host plant suitability for the two spotted spider mite Tetranychus urticae Koch (Acarina: Tetranychidae). This was done by determining the intrinsic rate of population increase, rm, of spider mites on leaf discs of plants from each of the cultivars. Large differences in rm values were found, ranging from 0.088/day on cultivar Bianca to 0.242/day on cultivar Sirtaki. This variation in rm was mainly caused by differences in developmental time of the spider mites. We assessed the performance of spider mites on young and old leaves of the two gerbera cultivars Bianca and Sirtaki. On Sirtaki the spider mites had a shorter developmental time and higher peak oviposition rate on young leaves than on old leaves. However, on Bianca such an effect was not found. We also determined the performance of two spider mite strains on the resistant gerbera cultivar Bianca. We compared the rm of a strain that had been reared on this cultivar for approximately half a year with the rm of a strain that was reared on bean. The rm of the strain that was reared on cultivar Bianca increased to 0.208/day, which is however still substantially lower than the rm on the susceptible cultivar Sirtaki.

DEVELOPMENT OF Tetranychus urticae KOCH (ACARI: TETRANYCHIDAE) IN DIFFERENT STRAWBERRY CULTIVARS

“…Krips et al (1998) reported that the development of T. urticae can be influenced both by host species and by intraspecific variations, that is, among different cultivars or materials of the same species. monteiro et al (2014) showed differences in T. urticae development time in different strawberry genotypes, with camarosa, Diamante and Seascape cultivars having the most negative effects on the mite.…”

Parâmetros biológicos e tabela de vida de Tetranychus urticae (Acari: Tetranychidae) em cultivares de mamão

“…sobre plantas menos favoráveis ao seu desenvolvimento pode ocorrer porque o ácaro necessita alocar energia, por exemplo, para destoxificação causada por compostos secundários produzidos pela planta hospedeira ou para evitar plantas com esses compostos secundários que são tóxicos (HELLE & SABELIS, 1985;GRECO et al, 2006). No entanto, KRIPS et al (1998) observaram que, em cultivares de gérbera resistentes ao T. urticae, mesmo após 10 gerações desse ácaro, o valor de r m se manteve baixo quando comparado à cultivar suscetível.…”

“…O desenvolvimento de T. urticae pode ser influenciado pela espécie de planta utilizada como hospedeira, assim como pode ocorrer variação intraespecífica, em função dos diferentes genótipos utilizados nos cultivos comerciais (KRIPS et al, 1998;GRECO et al, 2006; VAN DEN BOOM et al, 2003). No Brasil, há estudos que comparam o desenvolvimento de T. urticae em diferentes espécies e cultivares de plantas de importância econômica, como em algodoeiro Gossypium hirsutum (SILVA et al, 1985a;ESTEVES FILHO et al, 2010), morangueiro Fragaria x ananassa (LOURENÇÃO et al, 2000), tomateiro Lycopersicon spp.…”

Parámetros biológicos de Tetranychus desertorum (Acari: Tetranychidae) sobre hojas de poroto

“…La tasa de supervivencia fue máxima (100%) hasta el día 10, a partir del cual comenzó a disminuir, aunque manteniéndose hasta el día 14 sobre el 80%, alcanzando el 50% de mortalidad el día 16 (Figura 1). La tasa neta de reproducción (R 0 ) y la tasa intrínseca de crecimiento (r m ) son indicadores importantes de las dinámicas poblacionales de los tetraníquidos (Sabelis, 1985;Krisp et al, 1998). Las comparaciones de R 0 y r m ofrecen mayor información que la disponible de análisis independientes de parámetros de vida individuales (Zhang et al 2007).…”