Host‐plant acceptance and performance of Tetranychus urticae (Acari, Tetranychidae)

Abstract

Tetranychus urticae is a serious pest of several crops worldwide. It performs differentially on diverse hostplant species. Because dispersion is mainly passive, the process of host-plant selection should be viewed in terms of host-plant acceptance and not in terms of host finding. The objectives of this study were to investigate: (1) the acceptance of strawberry (S) in comparison with onion (O), leek (L) and parsley (P) by T. urticae; and (2) the suitability of these host plants for the performance of T. urticae, in terms of fecundity and survival. Host-plant acceptance was measured through females that settled on a test plant or females that left for another host plant. In another experiment, for a duration of 5 days, individual newly mated females were assigned to discs of each host plant and the fecundity, the maximum number of offspring obtained from one female that settled on the disc, the survival and the percentage of females that oviposited at least one egg were analysed. A choice test to measure the preference of females for different host plants was performed. Movements took place towards (S) from the three plants: (O), (L) and (P). Mites significantly moved to other places in the Petri dishes from leek-origin discs. Dispersal of T. urticae from (S) to other host-plant discs was similar for all plants. Mean fecundity was higher on (S) than on the other plants. The maximum number of offspring per female was highest on (S), lowest on (L) and (O), and intermediate on (P). Survival of females and percentage of females that laid at least one egg were independent of the host plant. The choice test showed that oviposition was higher on (S) and (P) and very poor on (L) and (O) and that more females settled on (S) and (P). Although mites migrated from parsley to strawberry, the first host plant has a higher acceptance of T. urticae in terms of maximum number of offspring per female than onion and leek, and a lower performance in terms of fecundity than strawberry. Parsley could be a good candidate for an associate plant in a strawberry crop; however, it needs more research under field conditions.

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

“…A redução nos valores de r m de Tetranychus spp. 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.…”

Performance of eighteen tetranychid mite species (Acari: Tetranychidae) on borage and strawberry

“…Spider mites may escape from unsuitable plants when they are inoculated on them. Greco et al (2006) reported the repeated escape of T. urticae from onion and leek as unsuitable plants, compared to strawberry as a suitable plant. With the combination of borage and borage in our experiments, we found that mites frequently moved between the two leaf discs during the 24 h observation.…”

“…To test settlement of females on borage and strawberry for 16 spider mite species, excluding T. evansi and T. ezoensis which failed to lay eggs on either strawberry or borage, we measured movement of adult females from a test plant where they had been released ('origin'), to another plant ('fate') (Yano et al, 1998;Greco et al, 2006). Two square leaf discs (10ϫ10 mm) were connected with a bridge of parafilm (1.5 mm width and 50 mm length), then five 2-3-d-old adult females were inoculated onto the 'origin' leaf disc and their positions-i.e., either 'origin' or 'fate'-were recorded after 24 h according to the methods of Yano et al (1998).…”

“…Often, host plant preference and performance are positively correlated, but not always-in some cases no correlation or a negative relationship was found between preference and performance (Thompson, 1988;Mayhew, 1997). Female spider mites forced to feed on non-preferred host plants generally have low fecundity (Yano et al, 1998;Greco et al, 2006). Because spider mites disperse mostly in a passive way through wind they are likely to end up near new hosts, hence their selection of host plants should be thought of in terms of acceptance, rather than host finding (Sabelis, 1985).…”