Tesis doctoral de Ana Morton Juan eda
The mediterranean flat-headed rootborer, capnodis tenebrionis (l.) (Coleoptera: buprestidae), is an economically important pest of stone fruit and seed fruit in mediterranean areas. This report summarizes the studies carried out to prove the efficacy of entomopathogenic nematodes to control c. Tenebrionis: entomopathogenic nematodes in the families steinernematidae and heterorhabditidae were isolated from stone-fruit orchards in two mediterranean regions of spain. A total of 630 soil samples (210 sites) from catalonia and 90 soil samples (30 sites) from murcia were evaluated resulting in 5.2% and 20% of the soils testing positive for nematodes, respectively. Ten steinernematid isolates and three heterorhabditid isolates were recovered using the galleria mellonella baiting method. Based on morphometric data, molecular data and cross-breeding experiments the nematode species were identified as steinernema feltiae and heterorhabditis bacteriophora. the efficacy of five entomopathogenic nematode strains of the families steinernematidae and heterorhabditidae was tested against the neonate larvae of capnodis tenebrionis. The nematode strains screened included two of steinernema carpocapsae (exhibit and m137), and one each of s. Feltiae (s6), s. Arenarium (s2), and heterorhabditis bacteriophora (p4). Exposure of neonate larvae of c. Tenebrionis to 10 and 150 infective juveniles (ijs) per larva (equivalent to 3 and 48 ijs/cm2 respectively) in test tubes with sterile sand resulted in mortality between 60 to 91% and 96 to 100%, respectively. At a concentration of 150 ijs/larva, all of the nematode strains were highly virulent. Both s. Carpocapsae strains (exhibit and m137) caused infection and mortality to larvae more quickly than the other strains. However, at a lower concentration assay (10 ijs/larva), s. Arenarium was the most virulent strain. The penetration rate as an indicator of entomopathogenic nematode infection was also evaluated. The highest value was recorded for s. Arenarium (36%), followed by h. Bacteriophora (30.6%), s. Feltiae (23.1%), and s. Carpocapsae (20.7%). the virulence of 14 steinernema feltiae isolates, one s. Carpocapsae and three heterorhabditis bacteriophora isolates was compared in the laboratory against larvae, pupae and adults of capnodis tenebrionis. Larval mortality ranged from 50 to 100% and pupae mortality from 0 to 70%. Adults were exposed to different nematode concentrations, 50 and 100 infective juveniles/cm2. Steinernema feltiae caused the highest mortality at the two doses tested, reaching 66.7% and 100%, respectively. Significant differences in mortality between c. Tenebrionis males and females were observed. The differences in virulence observed at each stage of c. Tenebrionis vary within a species and can be higher than differences among species. The results of this study suggest that some of the isolate strains have potential for improved biological control of c. Tenebrionis. environmental tolerance to heat, desiccation and hypoxia, the effect of temperature on infectivity and reproduction and nematode migration in sand columns were compared among isolates and one s. Carpocapsae strain. Results showed differences among species and a great variability within species. Beneficial traits for each strain were added up to identify a superior candidate to control mediterranean flat-headed rootborer, capnodis tenebrionis. When all analyzed factors were considered, three s. Feltiae isolates (bpa, sor and m116) obtained the best scores, and when hypoxia was removed, two of the strains (bpa and sor) continued ranking superior to other strains. the susceptibility of larvae of capnodis tenebrionis to 13 isolates of entomopathogenic nematodes was examined using gf-677@ potted trees (peach x almond hybrid) as the host plant. The nematode strains tested included nine steinernema feltiae, one s. Affine, one s. Carpocapsae and two heterorhabditis bacteriophora. Nematodes showed the ability to locate and kill larvae of c. Tenebrionis just after they enter into the roots of the tree. S. Feltiae strains provided an efficacy ranging from 79.68% to 88.24%. H. Bacteriophora strains resulted in control of 71.66 to 76.47%. S. Carpocapsae (b14) and s. Affine (gspe3) caused lower control of c. Tenebrionis larvae (62.03% and 34.76%, respectively). The influence of foraging strategy and the use of native nematodes to control c. Tenebrionis larvae inside the roots is discussed. the potential control of the entomopathogenic nematode steinernema feltiae (filipjev) (strain bpa), isolated from a dead c. Tenebrionis larva, was tested in a cherry tree orchard in ullastrell, barcelona (spain). Nematode infective juveniles (ijs) were applied by drench and injection. In both the treatments, a rate of 1 million ijs was applied per tree every week during 4 or 8 weeks, with a total dose of 4 x 106 ijs/tree and 8 x 106 ijs/tree. Number, stage and localization of insects in each tree trunk were recorded. In both the experiments, s. Feltiae significantly reduced the population of c. Tenebrionis providing control ranging from 88.3% to 97%. No significant differences were recorded between the different treatments. Persistence of nematodes was recorded until 6 weeks after application. Results indicate that the application of s. Feltiae (bpa) provides adequate control of c. Tenebrionis in cherry trees.
Datos académicos de la tesis doctoral «Los nematodos entomopatógenos (rhabditida: steinernematidae y heterorhabditidae) para el control del gusano cabezudo, capnodis tenebrionis (coleoptera: buprestidae).«
- Título de la tesis: Los nematodos entomopatógenos (rhabditida: steinernematidae y heterorhabditidae) para el control del gusano cabezudo, capnodis tenebrionis (coleoptera: buprestidae).
- Autor: Ana Morton Juan eda
- Universidad: Autónoma de barcelona
- Fecha de lectura de la tesis: 30/01/2009
Dirección y tribunal
- Director de la tesis
- Fernando García Del Pino
- Tribunal
- Presidente del tribunal: alejandro Palomo gonzález
- itamar Glazer (vocal)
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- (vocal)