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Chemical additives enhance the activity of a Bt‐based biopesticide targeting the beet webworm larvae

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Title Chemical additives enhance the activity of a Bt‐based biopesticide targeting the beet webworm larvae
 
Creator Opisa, S.
Akutse, K.S.
du Plessis, H.
Fiaboe, K.
Ekesi, S.
 
Subject AMARANTHUS
BACILLUS THURINGIENSIS
BORIC ACID
SYNERGISTIC EFFECT
INTEGRATED PEST MANAGEMENT
 
Description Spoladea recurvalis (Fbr.) (Lepidoptera: Crambidae) larvae can cause up to 100% foliage loss on amaranths during severe outbreaks. The Bacillus thuringiensis Subsp. kurstaki product Halt® is a biologically safe biopesticide recommended for the management of Spodoptera exigua (Hübner) and Plutella xylostella (Linnaeus). Spoladea recurvalis larvae are less susceptible to the product. Thirteen chemical additives to improve the efficacy of a Bt spray for control of S. recurvalis were evaluated in laboratory bioassays against second‐instar larvae. All the additives except calcium chloride caused an increase in mortality when applied in mixtures with Bt. Among the seven inorganic salts, boric acid was the only inorganic acid that caused more than 50% larval mortality. Boric acid at a concentration of 0.05% increased the activity of B. thuringiensis by 2.9‐fold. Boric acid had the shortest LT50 values of 5.3 days compared with all other combinations. Two nitrogenous compounds, peptone and sodium nitrate, caused 54 and 51% larval mortalities; however, this increase in efficacy was not significantly different from the mortalities caused by Bt applied without any additive. Urea increased larval mortality from 40% to 51%, although the increase was not significant from a Bt spray application only. Citric acid had no significant effect on the efficacy of Bt spray against S. recurvalis larvae. Overall, among the additives evaluated, the efficacy of Bt spray was most enhanced by boric acid and could be further evaluated under field conditions for validation, and integration into an Integrated Pest Management (IPM) strategy for S. recurvalis management.
German Federal Ministry for Economic Cooperation and Development
Peer Review
 
Date 2019-09-23T14:30:23Z
2019-09-23T14:30:23Z
2019-09-20
 
Type Journal Article
 
Identifier Opisa, S., Akutse, K.S., du Plessis, H., Fiaboe, K. & Ekesi, S. (2019). Chemical additives enhance the activity of a Bt‐based biopesticide targeting the beet webworm larvae. Journal of Applied Entomology,1-7.
0931-2048
https://hdl.handle.net/10568/103729
 
Language en
 
Rights Copyrighted; all rights reserved
 
Format 1-7
 
Source Journal of Applied Entomology