RESUMO
The present research addressed spray-drying and air-drying techniques applied to Metarhizium robertsii blastospores to develop wettable powder (WP) formulations. We investigated the effect of co-formulants on blastospore viability during drying and assessed the wettability and stability of formulations in water. The effect of oxygen-moisture absorbers was studied on the shelf life of these formulations stored at 26 °C and 4 °C for up to 90 days. Additionally, we determined the virulence of the best spray-dried and air-dried formulations against the corn leafhopper Dalbulus maidis. While sucrose and skim milk played an essential role as osmoprotectants in preserving air-dried blastospores, maltodextrin, skim milk, and bentonite were crucial to attain high cell survival during spray drying. The lowest wettability time was achieved with spray-dried formulations containing less Ca-lignin, while charcoal powder amount was positively associated with formulation stability. The addition of oxygen-moisture absorbers inside sealed packages increased from threefold to fourfold the half-life times of air-dried and spray-dried formulations at both storage temperatures. However, the half-life times of all blastospore-based formulations were shorter than 3 months regardless of temperature and packaging system. Spray-dried and air-dried WP formulations were as virulent as fresh blastopores against D. maydis adults sprayed with 5 × 107 blastospores mL-1 that induced 87.8% and 70.6% mortality, respectively. These findings bring innovative advancement for M. robertsii blastospore formulation through spray-drying and underpin the importance of adding protective matrices coupled to oxygen-moisture absorbers to extend cell viability during either cold or non-refrigerated storage. KEY POINTS: ⢠Cost-effective wettable powder formulations of M. robertsii blastospores were developed. ⢠Bioefficacy of formulations against the corn leafhopper was comparable to fresh blastospores. ⢠Cold storage and dual oxygen-moisture absorber are critical for extended shelf life.
Assuntos
Hemípteros , Metarhizium , Animais , Dessecação , VirulênciaRESUMO
BACKGROUND: The hornworn Erinnyis ello is the major pest of natural rubber crops in Colombia, mainly controlled using toxic chemical insecticides. The use of E. ello Betabaculovirus is an environmentally sustainable alternative for its control. The aim of the present work was to characterize a prototype biopesticide formulation and evaluate its efficacy under different conditions. RESULTS: Quality control evaluations of formulated biopesticide revealed that all the parameters evaluated were under the permissible level. The lethal concentrations LC50 and LC90 of the biopesticide were 4.3 × 103 and 5.5 × 104 occlusion bodies (OBs) mL-1 , respectively. Biopesticide efficacies against second and fourth instar larvae under greenhouse conditions were higher than 80%. Evaluation of two application rates in a clonal garden resulted in 84% and 88% efficacy, comparable to that obtained with the chemical. The biopesticide in a commercial plantation showed efficacies between 74% and 82%. Biopesticide post-application persistence was estimated at least in 1 week under field natural conditions. Results allowed selection of the lowest evaluated dose (1 × 1011 OBs ha-1 ) as the basis for further field evaluations. CONCLUSION: Formulated ErelGV showed high efficacy to control the hornworm in rubber crops and high potential to be included in integrated pest management programs, thus it could be an interesting alternative to replace agrochemicals. © 2018 Society of Chemical Industry.
Assuntos
Baculoviridae/fisiologia , Hevea , Mariposas/virologia , Controle Biológico de Vetores/métodos , Animais , Ambiente Controlado , Laboratórios , Controle de QualidadeRESUMO
Schistosomiasis is a snail-transmitted infectious disease affecting over 200 million people worldwide. Snail control has been recognized as an effective approach to interrupt the transmission of schistosomiasis, since the geographic distribution of this neglected tropical disease is determined by the presence of the intermediate host snails. In a recent Scoping Review published in Infectious Diseases of Poverty, Coelho and Caldeira performed a critical review of using molluscicides in the national schistosomiasis control programs in Brazil. They also described some chemical and plant-derived molluscicides used in China. In addition to the molluscicides described by Coelho and Caldeira, a large number of chemicals, plant extracts and microorganisms have been screened and tested for molluscicidal actions against Oncomelania hupensis, the intermediate host of Schistosoma japonicum in China. Here, we presented the currently commercial molluscicides available in China, including 26% suspension concentrate of metaldehyde and niclosamide (MNSC), 25% suspension concentrate of niclosamide ethanolamine salt (SCNE), 50% niclosamide ethanolamine salt wettable powder (WPN), 4% niclosamide ethanolamine salt dustable powder (NESP), 5% niclosamide ethanolamine salt granule (NESG) and the plant-derived molluscicide "Luowei". These molluscicides have been proved to be active against O. hupensis in both laboratory and endemic fields, playing an important role in the national schistosomiasis control program of China. Currently, China is transferring its successful experiences on schistosomiasis control to African countries. The introduction of Chinese commercial molluscicides to Africa, with adaptation to local conditions, may facilitate the progress towards the elimination of schisosomiasis in Africa.