Search

Comprehension of the basic aspects of entomopathogenic fungi development and detailed knowledge of nutritious requirements for their growth and sporulation are fundamental for mass production and commercialization. The objective of this study was to evaluate the production of blastospores in submerged culture medium and of conidia in biphasic culture of four native isolates and a B. bassiana strain showing potential for the control of Diaphorina citri (Hemiptera: Liviidae), which belong to the collection of the FCB-UANL Institute of Biotechnology, México. The experimental design was completely randomized and means were compared using Tukey test (p£0.05). In the liquid culture medium formulated with glucose and casamino acids, at 72 h, blastospore production had the highest (p£0.05) concentration for GHA strain (2.20×10-8 mL-1) and biomass of 26 gL-1, while the HIB-4 isolate showed the lowest blastospore production (p£0.05) (5.25×107 m L-1) and biomass of 7 g L-1. Isolate HIB-2 had 56 % germination in diatomaceous earth for support, being the highest value among the studied fungi. In solid hase (rice grain), at 14 d of incubation, HIB-4 isolate presented a production of 1.82×109 conidia g-1, and GHA strain producted was 2.35×108 conidia g-1. Viability was higher than 90 % for all fungi during 4 weeks of storing at 4 °C. Thus, it is feasible produce blastospores and conidia of native isolates of B. bassiana with the potential of controlling pests which affect the citrus-growing regions of México. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB), considered one of the most lethal diseases of citrus worldwide, has reached the main areas of Mexican lime (Citrus latifolia Tanaka) fruit production on the Pacific coast of México. Growers have initiated intensive use of insecticides in order to control populations of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), the vector of the pathogen, 'Candidatus Liberibacter asiaticus' associated with huanglongbing. Presently, costs of insecticides and the side effects of their use are major concerns, because they could impair the management strategy against the vector; and thus, ecologically and economically viable alternatives to conventional insecticides are required in the short term. Therefore the goal of this study was to evaluate the pathogenicity of 27 native isolates and 3 strains of entomopathogenic fungi and determine their potential as biological control agents of D. citri by using 2 different bioassay methods. Bioassays were performed under laboratory conditions (26 ± 2 °C, 60 ± 5% RH and 16:8 h L:D) by exposing adult insects to a concentration of 1 × 108 conidia per milliliter using 2 different application methods, i.e., spraying the spores onto the citrus seedlings and spraying the spores directly onto the adult psyllids. The results showed that by direct spraying the adults, HIB-24 (B. bassiana) and HIB-32 (I. fumosorosea) isolates showed the highest mortality (60.66%). Regarding spraying of the seedlings, HIB-19 (I. fumosorosea) showed the highest percentage of mortality (62.02%). The results from this study demonstrate potential for using entomopathogenic fungi in the management of D. citri in México. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate pathogenicity and effect of four isolated native and a strain of Isaria fumosorosea on beet armyworm, Spodoptera exigua (Hübner), and corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). Bioassays in a laboratory used neonate larvae of beet armyworm and corn earworm reared on artificial diet, which were inoculated by spraying or immersing with suspensions of 1 × 108 ml-1 conidia of I. fumosorosea, and subsequently incubated at 26°C, 65 ± 5% relative humidity, and 14:10 light: dark hours. Isolated HIB-30 killed the most immersed corn earworms, but fewest beet armyworms. HIB-30 most disrupted metamorphosis, 40%, by immersing beet armyworms, while HIB-29 and Pfr-612 least interrupted metamorphosis (8%), by spraying and immersing, respectively. [ABSTRACT FROM AUTHOR]

A Multiplex PCR assay for the detection of Porphyromonas gingivalis and Streptococcus intermedius in chronic periodontitis is presented. A total of 180 samples from 65 adults with untreated periodontitis and 17 healthy volunteers were taken and processed in a simple boiling step. Cell lysates were used as DNA source for multiplex PCR assays. Primers were designed from 16S rRNA gene sequences from the GenBank-EMBL database showing specificity for target pathogens. This multiplex PCR system could detect 8.2 P gingivalis and S. intermedius cells. In untreated periodontitis patients, only 78.5% were positive for one or both bacteria; 37% were positive for P gingivalis only, 17% for S. intermedius and 24.5% for both. P. gingivalis was detected in 23.5% of healthy volunteers, while S. intermedius was not detected in the same patients. The distribution of these bacteria was related to the periodontal probing depth, while 95.23% of patients with pockets wih 6 to 7 mm deep were positive for either or both, only 70.45% of of them with 4 to 5 mm pockets were positive.

A simplified amplified-fragment length polymorphism (AFLP) method was used to genotype Pichia pastoris strains obtained by transformation of P. pastoris strain GS115 with a single integration vector. A total of 14 transformants and 3 control strains were analyzed, which generated 16 different band patterns. A clonal variation was obtained after the transformation process due to genetic differences generated during the transformation event of the host strain. Furthermore, the cluster analysis showed that the transformants with lesser genetic differences with respect to the P. pastoris host strain are the recombinant strains with the highest level of recombinant protein production.