RESUMEN
Spittlebugs from the genus Aeneolamia are important pests of sugarcane. Although the use of the entomopathogenic fungus Metarhizum anisopliae s.l. for control of this pest is becoming more common in Mexico, fundamental information regarding M. anisopliae in sugarcane plantations is practically non-existent. Using phylogenetic analysis, we determined the specific diversity of Metarhizium spp. infecting adult spittlebugs in sugarcane plantations from four Mexican states. We obtained 29 isolates of M. anisopliae s.str. Haplotype network analysis revealed the existence of eight haplotypes. Eight selected isolates, representing the four Mexican states, were grown at different temperatures in vitro; isolates from Oaxaca achieved the greatest growth followed by isolates from Veracruz, San Luis Potosi and Tabasco. No relationship was found between in vitro growth and haplotype diversity. Our results represent a significant contribution to the better understanding of the ecology of Metarhizum spp. in the sugarcane agroecosystem.
Asunto(s)
Hemípteros/microbiología , Metarhizium/clasificación , Control Biológico de Vectores , Filogenia , Saccharum , Animales , Metarhizium/patogenicidad , MéxicoRESUMEN
Ecological immunology assumes that the host immune efficiency is correlated with its survival after pathogen challenge. To test this hypothesis, we challenged Phyllophaga polyphylla (Bates) larvae with the naturally occurring fungus Metarhizium pingshaense on two consecutive years (2011 and 2012). In each year, we injected the blastospores of M. pingshaense and then used levels of prophenoloxidase (proPO), phenoloxidase (PO) and total haemolymph serum protein as indicators of immune efficiency. Larvae were injected with (1) phosphate buffered saline (PBS) + Tween and viable blastospores of M. pingshaense, (2) PBS + Tween and non-viable blastospores of M. pingshaense, (3) PBS + Tween, or (4) non-manipulated. Overall, levels of PO, proPO and total haemolymph serum protein in larvae after 12 h were similar amongst treatments within each year of collection. However, larvae collected in 2011 showed higher PO and proPO activity but lower total haemolymph serum protein compared with larvae collected in 2012. A survival study injecting viable blastospores showed that larvae collected in both years died within 48 h; however, when non-viable blastospores were injected, which were still toxic to larvae, mortality was greater in larvae collected in 2011 compared with larvae collected in 2012. Altogether, these results indicate that PO, proPO and total haemolymph serum protein do not predict immune strength of P. polyphylla against blastospores of M. pingshaense, but higher values of PO and proPO were correlated with higher survival rates against non-infective but toxic agents. The possible role of some abiotic factors over the differences observed for immune components of P. polyphylla in different years of collection is discussed.
Asunto(s)
Escarabajos/inmunología , Metarhizium/patogenicidad , Animales , Escarabajos/microbiología , Hemolinfa/inmunología , Proteínas de Insectos/análisis , Larva/inmunología , Larva/microbiología , Factores de TiempoRESUMEN
The effect of order of inoculation of Pandora blunckii and Zoophthora radicans co-infecting Plutella xylostella (L.) (Lepidoptera: Plutellidae) was investigated. After co-inoculation, the proportion of larvae infected by either species was greatly reduced compared to when they were inoculated singly. The order of inoculation influenced the final outcome; the isolate inoculated last always killed more larvae than the isolate inoculated first.
Asunto(s)
Entomophthorales , Lepidópteros , Control Biológico de Vectores/métodos , AnimalesRESUMEN
A series of 2-deoxy-D-glucose resistant mutants was obtained from wild type Beauveria bassiana 88 (Bb 88) by UV irradiation. Five mutants were characterized on Sabouraud Dextrose Agar and Chitin Agar for both radial extension rate (V(r)) and specific growth rate (micro). These values were obtained after adjusting morphometric data to a mathematical model used for filamentous fungi. Additionally, the protease and lipase potency index, conidial size, viability, and production levels were analyzed. The highest values for those physiological measurements were obtained by mutant 882.5 which, relative to Bb 88, showed a 30% reduction in half-life (LT(50)) on Sphenarium purpurascens, 70% on Acheta domesticus, and 71% on Tenebrio molitor larvae and adults. The half lethal concentration (LC(50)) on T. molitor larvae was 2.8 x 10(5)conidia/mL (con/mL) and 1.5 x 10(6)con/mL, respectively, for mutant 882.5 and Bb 88. This demonstrates that mutant 882.5 is more virulent, with up to an 80% reduction in LC(50). This work provides a convenient method for improving strains to be used in biocontrol as a suitable alternative to transgenic constructs.
Asunto(s)
Beauveria/patogenicidad , Desoxiglucosa/farmacología , Animales , Beauveria/efectos de los fármacos , Beauveria/genética , Escarabajos/crecimiento & desarrollo , Escarabajos/microbiología , Farmacorresistencia Fúngica , Saltamontes/crecimiento & desarrollo , Saltamontes/microbiología , Gryllidae/crecimiento & desarrollo , Gryllidae/microbiología , Larva/microbiología , Mutación , Control Biológico de VectoresRESUMEN
The objective of this work was to determine, trough bioassays, the most virulent strains of Hirsutella to be used as a control alternative in a pest intregrated wield program are those which are most pathogenic to CL50 just as H. nodulosa (HnC83) with 5 x 10(5) conidia/ml, and H. thompsonii (HtMOR and HtM5) with 1 x 10(6) and 1.1 x 10(6) conidia/ml respectively. The strain we recommend to attack Tetranychus urticae is H. thompsonii HtMOR. Although it did not seem to be the most aggressive to CL50, it was the strain that required the lowest concentration (0.0014%/1.5 x 10(10)) to kill 95% of the population evaluated. At the same time, the strain that we considered as having a lower virulence was HtM2 (4 x 10(6) c/ml) and the lowest virulence was detected both in HtC59 and HtC77 (1 x 10(10) c/ml).
Asunto(s)
Bioensayo , Hongos/patogenicidad , Ácaros/microbiología , Animales , Frutas/microbiologíaRESUMEN
A large-scale method for producing fungal pathogens for mites, Hirsutella thompsonii and H. nodulosa in two phase culture (liquid and solid), was developed to induce conidiogenesis. The vegetative growth that was obtained in the liquid media of soy meal with shaking, from an inoculum 0.5 g wet weight equivalent to 0.1 g of dry weight, was inoculated on eight solid supports. Generally for most of the strains, the three supports yielding greater conidiogenesis were rice, barley and bran, excluding the strains whose greater sporulation is achieved in rice, oats and sorghum, sorghum and oats as compared to barley and bran, respectively. Maximum production of conidia was obtained with HtM2, HtM4481 and HtC59 strains of H. thompsonii, which reached on solid support 334.75, 269.68 and 137.12 x 10(7) conidia/g, respectively.