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Aedes aegypti (Linn.) incidence has increased in recent years, causing human viral diseases such as dengue, which are often fatal. Beauveria bassiana (Bals., Vuillemin) efficacy for Ae. aegypti biological control has been evidenced but it relies on host susceptibility and strain virulence. We hypothesized that B. bassiana conidia microgranular formulations (MGF) with the additives acetone, lactic acid, and sugar increase Ae. aegypti adult exposure, thus improving their biocontrol effectiveness. Beauveria bassiana strain four (BBPTG4) conidia stability was assessed after 0 d, 5 d, and 30 d storage at 25 °C ± 2 °C with additives or in MGF after 91 d of storage at 25 °C ± 2 °C or 4 °C ± 1 °C, whereas mortality was evaluated after adult exposure to MGF + conidia, using home-made traps. Additives did not show toxicity to conidia. In addition, we observed that sugar in MGF increased Ae. aegypti adults' attraction and their viability resulted in a 3-fold reduction after 5 d and 1- to 4-fold decrease after 30 d of storage, and formulations were less attractive (p < 0.05). Conidia stability was higher on MGF regardless of the storage temperature, losing up to 2.5-fold viability after 91 d. In conclusion, BBPTG4 infected and killed Ae. aegypti, whereas MGF attracting adults resulted in 42.2% mortality, increasing fungus auto dissemination potential among infected surviving adults. It is necessary to further evaluate MGF against Ae. aegypti in the field. [ABSTRACT FROM AUTHOR]

Beauveria bassiana (Bals.) Vuillemin (B. bassiana) is an entomopathogenic fungus that establishes endophytic symbiosis with plants. In the present study, the effects of B. bassiana strains colonization in growing Zea mays L. (Z. mays), crop production, and drought tolerance were evaluated. Z. mays seeds were inoculated with B. bassiana strains (GHA, PTG4, and PTG6), using 1 × 106 blastospores/mL and methyl cellulose (MC) or cornstarch (CS) as adherents. Colonization was determined by B. bassiana recovery from plant tissues plated on PDA medium. Plant height, fresh and dry weight, and flowering time were analyzed to assess plant performance. Drought tolerance was evaluated by stopping watering for 10 days, watering again, and determining vigor recovery after 24 h. Results showed 100% endophytic roots colonization, regardless of adherent type or strain tested. Colonization was variable in shoots and leaves, but GHA strain achieved the highest inoculation rates, including 88% in stems and 50% in leaves, which did not depend on adherent type used; for PTG4 strain, adherent type had an important effect (MC = 100% stems and leaves; CS = 63% stems and 25% leaves). For PTG6 strain, the best adherent type was CS (71% stems and 75% leaves), whereas MC showed variable inoculation percentage (25% stems and 75% leaves). Interestingly, only MCPTG4 treatment showed consistent positive effects on germination percentage (day 5 = 46 ± 2%; day 14 = 87 ± 7%) compared with controls (CC = 63 ± 4%, CMC = 50 ± 3%, CCS = 47 ± 0%). In addition, the other treatments showed low germination percentages at day 5 (7 ± 7% to 46 ± 2%), which recovered at day 14 (53 ± 0% to 73 ± 8%), except for MCPTG6 treatment with 23 ± 10% germination. About plant performance, not significant effects on plant height and fresh/dry weight in all the treatments were observed. However, B. bassiana-treated plants, using either GHA, PTG4 or PTG6 strains, and MC as adherent, showed tolerance to drought and flowered one to two weeks earlier, providing evidence supporting further applications of these seed treatments in agricultural systems, for abiotic stress sustainable management practices. [ABSTRACT FROM AUTHOR]

The Mexican bean beetle, Epilachna varivestis Mulsant, is an important pest of bean ( Phaseolus vulgaris L.) crops in Mexico and eastern United States. The Beauveria bassiana isolates TM0307 and SyDBbh5001M require large amounts to be effective in the field. Liquid culture medium containing cotton ( Gossypium hirsutum L.) flour was evaluated to improve their virulence against E. varivestes. Virulence of B. bassiana blastospores was evaluated using various culture media and Sabouraud dextrose broth as a control, testing potential of cotton flour versus peptone as a nitrogen source, and colloidal chitin and Lepidoptera exuvia as sources of chitin. Samples were collected every 24 hours, and production of cuticle-degrading proteases (Pr1 and Pr2) and chitinase (NAGase) was determined during 5 days. The lowest enzyme production was observed in Sabouraud dextrose broth and colloidal chitin cultures, whereas the highest production was observed in chitin with cotton flour (Pr1 = 23.2, 2.3, and 126.2 U/ml; Pr2 = 12.7, 2.3, and 48.7 U/ml; NAGase = 5.4, 0.6, and 9.1 U/ml in Sabouraud dextrose broth, colloidal chitin, and chitin with cotton flour cultures, respectively). The LC50 in chitin with cotton flour versus Sabouraud dextrose broth media was evaluated by testing six doses against E. varivestis third-instar larvae; median survival time (ST50) was measured by testing 1 × 108 blastospores per milliliter. Significant lower LC50 and ST50 values were observed by blastospores produced in chitin with cotton flour medium (2.1 ± 1.7 to 2.8 × 106 blastospores per milliliter and 2 days), compared with those on Sabouraud dextrose broth (9.8 ± 6.3 to 15.9 × 106 blastospores per milliliter and 4 days), respectively. Results indicated potential of cotton flour to increase virulence of B. bassiana blastospores against E. varivestis third-instar larvae by enhancing production of insect cuticle-degrading enzymes. [ABSTRACT FROM AUTHOR]

Biological control of Bactericera cockerelli using a combination of parasitoids and pathogens has potential. However, their combined use could result in complex multitrophic interactions, the outcomes of which are uncertain. In this study we evaluated the effects of applications of two Beauveria bassiana isolates (pathogen) on the parasitoid Tamarixia triozae during its development on the host, B. cockerelli . Three concentrations (LC 20 , LC 50 and LC 90 values against B. cockerelli ) of the fungal isolates BB40 and GHA were applied to 4th instar B. cockerelli nymphs that had been successfully parasitized by T. triozae 3, 5, 8 or 12 days earlier at 25 °C. The greatest infection of T. triozae was observed when the calculated LC 90 was inoculated, regardless of isolate, and when the parasitoids were 3–5 days old. The lowest infection of T. triozae was observed when they were 8 and 12 days old regardless of isolate or conidial concentration. The highest parasitoid emergence was achieved in the untreated control compared with all other treatments and combinations tested. Within treatments, the highest parasitoid emergence was obtained at the lowest B. bassiana concentration tested and when the pathogen was applied to B. cockerelli supporting 12 day-old parasitoids. Longevity of adult parasitoids that had emerged from B. cockerelli nymphs was greatest in the control treatment, followed by those from nymphs treated with GHA when applied to B. cockerelli supporting 12 day-old parasitoids. In conclusion, biological control of B. cockerelli may require the synchronized use of high B. bassiana concentrations, applied only on T. triozae late pupal stage (8–12 days of development), in order to allow the parasitoid to survive and also achieve good overall pest control. [ABSTRACT FROM AUTHOR]

Bactericera cockerelli (Sulc.) is an important pest of solanaceous crops and a vector of the pathogen Candidatus Liberibacter psyllaurous . Biocontrol of this pest has been attempted with either entomopathogenic fungi or the parasitoid Tamarixia triozae (Burks), but prior to this study, their potential impact in combination had not been studied. The aim of the present study was to evaluate T. triozae parasitism rates on B. cockerelli nymphs that were previously infected for different periods of time by three isolates of Beauveria bassiana (Bals.) Vuill. Two native isolates (BB40 and BB42) and one commercial isolate (GHA) were used. The virulence of these isolates was first estimated against B. cockerelli and T. triozae . LC 50 values for the native isolates BB40 and BB42 against B. cockerelli were 9.5 × 10 5 and 2.42 × 10 6 conidia mL −1 respectively; they were significantly more virulent than isolate GHA with an LC 50 of 1.97 × 10 7 conidia mL −1 . However, isolate GHA was significantly more virulent against T. triozae with an LC 50 of 1.11 × 10 7 conidia mL −1 compared with LC 50 s of 1.49 × 10 7 and 1.14 × 10 8 conidia mL −1 for the native isolates BB40 and BB42 respectively. Groups of nymphs were then inoculated with LC 20 , LC 50 or LC 90 concentrations of each isolate and presented to T. triozae as hosts either on the day of inoculation or 1, 2, 3, 4, 5, 6 days after inoculation. Subsequent levels of parasitism were recorded. Overall, parasitism rates were similar in inoculated and control nymphs. No parasitism occurred in nymphs 6 days after fungal inoculation. Parasitoids used to parasitize uninoculated B. cockerelli nymphs survived significantly longer (7.8 days) than parasitoids that had been used to parasitize fungus-inoculated nymphs (7.3 days). This suggests an inability of the parasitoid to avoid infection when foraging on inoculated nymphs. In conclusion, although the parasitism rate in control and fungus-treated nymphs was similar, suggesting a combination of both biological control agents is possible, we believe there are also negative implications for the parasitoid because its survival was greatly reduced after attacking infected nymphs. [ABSTRACT FROM AUTHOR]