Genetic Variability ofAspergillus flavusIsolates from a Mississippi Corn Field

A nontoxigenicAspergillus flavusstrain, K49, is currently being tested as a biological control agent in corn fields in the Mississippi Delta. However, little is known about the overall genetic diversity ofA. flavusfrom year to year in corn fields and specifically in Mississippi. Our objective was to assess the genetic variability ofA. flavusisolates from different seasons, inoculum sources, and years, from a no-till corn field. Of the 175A. flavusisolates examined, 74 and 97 had the typicalnorB-cypAtype I (1.5 kb) and type II (1.0 kb) deletion patterns, respectively. Variability in the sequence of theomtAgene of the majority of the field isolates (n=118) was compared to strain K49. High levels of haplotypic diversity (24omtAhaplotypes; Hd = 0.61 ± 0.04) were found. Among the 24 haplotypes, two were predominant, H1 (n=71), which consists of mostly toxigenic isolates, and H49 (n=18), which consists of mostly atoxigenic isolates including K49. Toxigenic isolates were prevalent (60%) in this natural population. Nonetheless, about 15% of the population likely shared the same ancestral origin with K49. This study provides valuable information on the diversity ofA. flavus. This knowledge can be further used to develop additional biological control strains.

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Effect of Temperature on Life History and Parasitization Behavior of Trichogramma achaeae Nagaraja and Nagarkatti (Hym.: Trichogrammatidae)

Insects ◽

10.3390/insects11080482 ◽

2020 ◽

Vol 11 (8) ◽

pp. 482

Author(s):

Modesto del Pino ◽

Juan Ramón Gallego ◽

Estrella Hernández Suárez ◽

Tomás Cabello

Keyword(s):

Biological Control ◽

Life Table ◽

Biological Control Agent ◽

Control Agent ◽

Intrinsic Rate Of Increase ◽

Adult Longevity ◽

Type I ◽

Net Reproductive Rate ◽

Rate Of Increase ◽

Trichogramma Achaeae

Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) is currently used as biological control agent for several lepidopteran pests. Knowledge of thermal requirements is essential to optimize its rearing procedures and inundative releases. The biological characteristics and two-sex life table parameters of T. achaeae were determined at five constant temperatures (15, 20, 25, 30, and 35 °C) using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. T. achaeae was able to develop and survive from 15 °C to 30 °C, but not at 35 °C. Temperature significantly affected the preadult development time and adult longevity, decreasing when temperature increased from 15 °C to 30 °C. Temperature significantly altered the sex ratio, being female biased between 15 °C and 25 °C. Age-stage, two-sex life table analysis indicated that net reproductive rate (R0) was highest at 20 °C. Both the intrinsic rate of increase (r) and finite rate of increase (λ) increased with increasing temperature, while the mean generation time (T) decreased significantly. In addition, functional response of T. achaeae was studied, being significantly affected by temperature and host egg density, displaying a Holling type-I at 15 °C and a Holling type-II at 25 °C. The relevance of these results is discussed for the use of T. achaeae as biological control agent.

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LEVANTAMENTO DA DISPERSÃO E VARIABILIDADE GENÉTICA DE Tectococcus ovatus (HETEROPTERA: ERIOCOCCIDAE) NAS REGIÕES DE OCORRÊNCIA NATURAL DE Psidium cattleianum (MYRTACEAE)

FLORESTA ◽

10.5380/rf.v43i2.21344 ◽

2013 ◽

Vol 43 (2) ◽

pp. 289

Author(s):

Luciene Erica Cordeiro Ranuci ◽

Josiane de Carvalho Vitorino ◽

Tracy Johnson ◽

Marcelo Diniz Vitorino

Keyword(s):

Biological Control ◽

Genetic Variability ◽

Rio De Janeiro ◽

Biological Control Agent ◽

Rio Grande ◽

Control Agent ◽

Rio Grande Do Sul ◽

Santa Catarina ◽

Psidium Cattleianum ◽

Different Populations

A espécie Psidium cattleianum é considerada uma das maiores ameaças ao ecossistema e à biodiversidade nas ilhas do Havaí. Buscando controlar sua disseminação, adotaram-se técnicas de controle biológico. Dentre as várias espécies estudadas como agente de controle, Tectococcus ovatus (Heteroptera: Eriococcidae) apresentou o maior nível de especificidade. Este trabalho teve como objetivo verificar a existência de variabilidade genética entre e dentro das diferentes populações de Tectococcus ovatus amostradas, utilizando a técnica de PCR-RAPD. As análises foram realizadas a partir de fêmeas coletadas nos estados do Rio de Janeiro, Paraná, Santa Catarina e Rio Grande do Sul. Dos oito iniciadores de PCR-RAPD testados, quatro foram utilizados nas análises, revelando marcadores monomórficos e polimórficos com uma freqüência variável, tanto para os indivíduos de uma mesma localidade quanto para os indivíduos de localidades diferentes. Através da análise de agrupamento de caracterização molecular, foi possível verificar a formação de dois grupos distintos, A e B, apresentando uma variabilidade genética de 44%. Os resultados obtidos através da análise dos marcadores RAPD foram úteis na verificação de variação e forneceram informações sobre os níveis de variabilidade e similaridade entre e dentro das diferentes populações de Tectococcus ovatus.Palavras-chave: Controle biológico; variabilidade genética; PCR-RAPD. AbstractSurvey of dispersal and genetic variability of Tectococcus ovatus (Heteroptera: Eriococcidae) in the regions of natural occurence of Psidium cattleianum (Myrtaceae). The species Psidium cattleianum is considered one of the greatest threats to the ecosystem and biodiversity of the islands from Hawaii. Seeking to control its dissemination, techniques of biological control were used. Among the various species studied, as a biological control agent, Tectococcus ovatus showed a higher level of specificity. This work had as its aim to verify the existence of genetic variability among and inside different populations of Tectococcus ovatus sampled, using the technique of PCR-RAPD. The analyses were made from females collected in the states of Rio de Janeiro, Paraná, Santa Catarina and Rio Grande do Sul. From the eight initiators of PCR-RAPD tested, four were used in the analyses, revealing monomorphic and polimorphic markers with a variable frequency, to the individuals of one place as well as to the individuals of different places. Through the analysis of the grouping of molecular characterization it was possible to verify a formation of two distinctive groups A and B, presenting a genetic variability of 44%. The results obtained through the analysis of RAPD markers were useful to variation verification and provided safe information about the levels of variability and similarity amongst and inside the different populations of Tectococcus ovatus.Keywords: Biological control; genetic variability; PCR-RAPD.

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Complete Genome Sequence Data of rare Actinomycetes Strain, Saccharothrix texasensis strain 6-C, a Biological Control Agent for Potato Late Blight

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-10-20-0300-a ◽

2021 ◽

Author(s):

Shun Feng ◽

Yongfei Jian ◽

Liang Jin ◽

Shicai Tang ◽

Zhengguo Li

Keyword(s):

Biological Control ◽

Late Blight ◽

Genome Sequence ◽

Complete Genome ◽

Biological Control Agent ◽

Gc Content ◽

Potato Late Blight ◽

Control Agent ◽

Type I ◽

Rare Actinomycetes

A rare actinomycetes strain of Saccharothrix texasensis strain 6-C, has been isolated from the potato rhizosphere and it was shown to act as a biological control agent to potato late blight. It is also the first report on Saccharothrix inhibiting P. infestans. Here, we present the complete genome data of S. texasensis strain 6-C, assembled by sequencing reads obtained by both PacBio and Illumina technologies with annotation. The final assembled genome length is 9,045,220 bp, with no gaps, no plasmid, and its GC content is 72.39%. Nine non-ribosomal peptide synthetase (NRPS), five type I polyketide synthase (T1PKS), four terpene and three lanthipeptide gene clusters were identified in the genome, which would be likely to encode lots of antimicrobial active substances to help host plants against disease. This genome sequence could contribute to investigations of the molecular basis underlying the biocontrol activity of this Saccharothrix strain.

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