Preparation, characterisation and cell viability of encapsulated Trichoderma asperellum in alginate beads.

Aim: The encapsulation of Trichoderma asperellum BRM-29104 using Ca-alginate matrix was evaluated.Methods: Intact and freeze-dried beads containing submerged conidia and microsclerotia (MS) of T. asperellum grown in liquid culture were prepared and characterised. Beads were stored at 8, 25, and 35 °C over 120 days.Results: The mean sizes of beads before and after freeze-drying were 2.5 ± 0.2 mm and 1.5 × 1.1 mm (± 0.1 mm), respectively. Freeze-dried beads stored at 8 °C were more effective in maintaining conidia concentration, while MS concentrations yielded 102 MS/g for both beads at 8 and 25 °C. The concentration of viable cells in freeze-dried beads stored at 8 °C attained 3.0 × 108 CFU/g after 120 days. FIRT analysis showed an interaction between the alginate and the cell wall of the fungus.Conclusion: These findings support the use of alginate beads followed by freeze drying and cold storage for maintenance of viability of T. asperellum.

Within-Host Competition between Two Entomopathogenic Fungi and a Granulovirus in Diatraea saccharalis (Lepidoptera: Crambidae).

We provide insights into how the interactions of two entomopathogenic fungi and a virus play a role in virulence, disease development, and pathogen reproduction for an economically important insect crop pest, the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae). In our model system, we highlight the antagonistic effects of the co-inoculation of Beauveria bassiana and granulovirus (DisaGV) on virulence, compared to their single counterparts. By contrast, combinations of Metarhizium anisopliae and B. bassiana, or M. anisopliae and DisaGV, have resulted in additive effects against the insect. Intriguingly, most cadavers that were derived from dual or triple infections, produced signs/symptoms of only one species after the death of the infected host. In the combination of fungi and DisaGV, there was a trend where a higher proportion of viral infection bearing conspicuous symptoms occurred, except when the larvae were inoculated with M. anisopliae and DisaGV at the two highest inoculum rates. Co-infections with B. bassiana and M. anisopliae did not affect pathogen reproduction, since the sporulation from co-inoculated larvae did not differ from their single counterparts.

A Rapid Sampling Plan for Scirtothrips dorsalis (Thysanoptera: Thripidae) on Container Shrub Rose (Rosa 'Radrazz').

The development of simple and reliable pest sampling programs is needed for growers to adopt economic or aesthetic injury levels. We developed a sampling plan for monitoring chilli thrips Scirtothrips dorsalis Hood populations on KnockOut shrub roses under simulated nursery conditions. The distribution of S. dorsalis among different plant structures revealed that most adults and larvae are found on foliar terminals, when compared with buds and flowers. Based on thrips distribution, the third leaf of actively growing terminals was used to determine a sequential sampling model. Thrips had an aggregated distribution, based on Taylor's power law and Iwao's mean crowding index, with both models showing a good fit (i.e., R2 of ∼0.8 and ∼0.9, respectively). Based on these model parameters, the number of samples required to estimate populations with a 10% precision was ∼30 leaves according to Green's and Kuno's enumerative sequential sampling plans. A binomial model also estimated the proportion of infested leaf terminals as a function of insect density with an R2 value of 0.85. An additional study demonstrated that correlation between visual damage to the third leaf terminal and initial thrips populations was modeled by simple power functions. This finding suggests that a more rapid visual sampling of plant damage can be used to indirectly estimate S. dorsalis populations. Our sampling plan provides a tool to monitor S. dorsalis populations that could be used to help make management decisions for this pest in commercial nurseries.