Revista Colombiana de Entomología (2017) 43, 167-172

Arthur Vieira Ribeiro, Carlos Eduardo Almeida Luz, Cristina Schetino Bastos, Yann Schmidt Teichmann Krieger, Nathalia Henriques da Silva and Weslley Brandão da Silva (2017)
Toxicity of botanical and synthetic formulations to the maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae)
Revista Colombiana de Entomología 43 (2), 167-172
Abstract: Maize is attacked by various pest species, including the key-pest of stored maize, Sitophilus zeamais (Coleoptera: Curculionidae). This study determined the LC₅₀ and LD₅₀ of neem-based insecticides (AzaMax^® and Natuneem^®) in comparison to a synthetic pyrethroid insecticide (Decis^® 25 CE) to S. zeamais. The bioassays consisted of insects' exposure alone (topical application with microsyringe) and exposure of both insects and seeds treated simultaneously. The final bioassays used four to six concentrations of each formulation per bioassay, diluted in distilled water. The bioassays were run with the use of 10 non-sexed adults of S. zeamais per replication and mortality was assessed after 48 h of exposure. The data regarding concentration and dose-mortality were analyzed by probit analysis. Both LC₅₀ and LD₅₀ were used to calculate LCR and LDR's and their respective confidence interval (CI). After using topical application, the bioassays yielded LD₅₀-values of 51.32, 76.76 and 42.75 µL of AzaMax, Natuneem and Decis/g of insects, respectively. The bioassays with simultaneous exposure of both insects and seeds yielded LC₅₀-values of 4.01, 4.46 and 0.41 µL of AzaMax, Natuneem and Decis/g of seeds, respectively. Regarding the fact that there were no significant differences between the LC₅₀-values of the botanical insecticides, both of them can be used to manage S. zeamais infesting stored corn. The cost to treat maize and to obtain effective control of S. zeamais is cheapest for Decis<Natuneem<Azamax. The LC₅₀-values found in our study would be equivalent to use 8.02, 8.92 and 0.82 L of AzaMax, Natuneem and Decis/ton of seeds.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: English)
Link to article at publishers website
Database assignments for author(s): Cristina S. Bastos

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sitophilus zeamais	Maize/corn (Zea mays)