scholarly journals Plant Abandonment by Busseola fusca (Lepidoptera: Noctuidae) Larvae: Do Bt Toxins Have an Effect?

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 77 ◽  
Author(s):  
Andri Visser ◽  
Hannalene Du Plessis ◽  
Annemie Erasmus ◽  
Johnnie Van den Berg
Keyword(s):  
Resistance Management ◽  
Leaf Tissue ◽  
Busseola Fusca ◽  
High Dose ◽  
Pest Species ◽  
Bt Maize ◽  
Resistance Evolution ◽  
Bt Toxins ◽  
Important Pest ◽  
Lepidoptera Noctuidae

Busseola fusca (Fuller; Lepidoptera: Noctuidae) is an important pest of maize in Africa and can be effectively controlled by Bt maize. However, the sustainability of this technology is threatened by resistance evolution, which necessitates the implementation of the high-dose/refuge insect resistance management (IRM) strategy. Despite the success of this IRM strategy, it is based on several assumptions about insect-hostplant interactions that are not always valid for different pest species. In this study, the plant abandonment behavior of Cry1Ab-resistant and susceptible B. fusca larvae were evaluated on a non-Bt, single toxin (Cry1Ab), and a pyramid event (Cry1.105 + Cry2Ab2) of maize over a four-day period. The aim was to determine if larvae are more likely to abandon maize plants that contain Bt-toxins than conventional non-Bt plants, and if resistance to the Cry1Ab-toxin affects this behavior. This study found that both Bt-resistant and susceptible B. fusca neonate larvae show feeding avoidance behavior and increased plant abandonment rates when exposed to Bt maize leaf tissue. The implications of these findings for the design of IRM strategies and choice of refuge structures are discussed in the context of Bt maize in Africa.

scholarly journals Bigger, Faster, Stronger: Implications of Inter-Species Interactions for IRM of Lepidopteran Pests of Bt Maize in Africa

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Andri Visser ◽  
Johnnie Van den Berg
Keyword(s):  
Species Interactions ◽  
Species Complex ◽  
Busseola Fusca ◽  
Single Species ◽  
High Dose ◽  
Bt Maize ◽  
Lepidopteran Pests ◽  
Hypothetical Scenario ◽  
Mixed Populations ◽  
Lepidoptera Noctuidae

Abstract A hypothetical scenario of mixed populations of Busseola fusca (Fuller) (Lepidoptera: Noctuidae), Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), and Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) was used as a model to investigate the potential effects of mixed populations of lepidopteran pests, on the design and implementation of insect resistance management (IRM) strategies for Bt maize (L.) (Poaceae) on smallholder farms in Africa. To predict the structure of such mixed populations in different agroecological zones, the biological and behavioral characteristics that affect the competitiveness of these species were identified and analyzed. Additionally, the validity of the assumptions that underlie the high-dose/refuge strategy was compared among the three species. Differences between the species, and the influence thereof on the choice of IRM strategy for a specific environment, were explored through analysis of three hypothetical scenarios. We suggest that the use of separate refuges as a component of an IRM strategy against mixed pest populations in smallholder Bt maize fields may be unwise. A seed mixture approach, coupled with an effective integrated pest management (IPM) strategy, would be more practical and sensible since it could limit the opportunity for a single species to dominate the species complex. The dynamic interactions in a multi-species community and domination of the species complex by a single species may influence moth and larval response to maize plants, which could lead to an increased infestation of Bt plants, and subsequent increased selection pressure for resistance evolution. This article provides insights into the unique challenges that face the deployment of Bt maize in Africa.

scholarly journals Practical Resistance of Ostrinia nubilalis (Lepidoptera: Crambidae) to Cry1F Bacillus thuringiensis maize discovered in Nova Scotia, Canada

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jocelyn L. Smith ◽  
Yasmine Farhan ◽  
Arthur W. Schaafsma
Keyword(s):  
Nova Scotia ◽  
Bacillus Thuringiensis ◽  
North America ◽  
Ostrinia Nubilalis ◽  
Leaf Tissue ◽  
High Dose ◽  
Bt Maize ◽  
Resistance Evolution ◽  
First Case ◽  
Laboratory Colonies

AbstractTransgenic maize, Zea mays L., modified to express insecticidal proteins from the bacterium Bacillus thuringiensis Berliner, was introduced in 1996 to control Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), a key maize pest in North America. The high-dose/refuge concept, developed to delay or prevent resistance evolution to this technology, has been exemplified by O. nubilalis as no cases of practical resistance were identified in >20 years. This study documents the first case of practical resistance to Cry1F Bt maize by O. nubilalis in North America. Four collections of O. nubilalis were made from Cry1F maize in Nova Scotia, Canada with unexpected injury (UXI) ranging from 30–70%. Greater survival of UXI collections was observed when larvae were exposed to the highest concentration of 200 ng Cry1F cm−2 in diet-overlay bioassays compared to susceptible laboratory colonies. Larvae also fed and survived on Cry1F leaf tissue in 7 d bioassays. A collection from non-Bt maize, 120 km west of the UXI region, also survived 200 ng Cry1F cm−2, but was susceptible to Cry1F leaf tissue. Detection of Cry1F-resistant O. nubilalis in what might be considered an insignificant maize-growing region indicates that a number of preventable causal factors may have been related to inadequate stewardship of Bt maize technology.

scholarly journals Modeling the Evolution of Resistance in Cotton Bollworm to Concurrently Planted Bt Cotton and Bt Maize in China

2021 ◽  
Author(s):  
Wenhui Wang ◽  
Feng Xu ◽  
Yunxin Huang ◽  
Hongqiang Feng ◽  
Peng Wan
Keyword(s):  
First Generation ◽  
Resistance Management ◽  
Northern China ◽  
Cotton Bollworm ◽  
Bt Cotton ◽  
Bt Maize ◽  
Bt Toxins ◽  
Evolution Of Resistance ◽  
The One ◽  
Lepidoptera Noctuidae

Abstract BackgroundTransgenic maize expressing toxins derived from the bacterium Bacillus thuringiensis (Bt) may be commercially planted in northern China where Bt cotton has been planted for more than two decades. While Bt maize brings additional benefits for insect control, it complicates the resistance management of cotton bollworm (CBW), Helicoverpa armigera (Lepidoptera, Noctuidae), a common target of Bt cotton and Bt maize.ResultsWe developed population genetic models to assess the risk of resistance in CBW when Bt cotton and Bt maize are planted concurrently. Model simulations showed that when natural refuges are absent, the time to resistance (TTR) is less than 10 generations in the case of one-toxin Bt cotton and one-toxin Bt maize, but is more than 30 generations in the case of two-toxin Bt cotton and two-toxin Bt maize. The differences in the TTR between the two cases become greater as the proportion of natural refuge increases. Among the parameters we investigated, the fitness cost has a relatively smaller effect on the TTR, while the dominance of resistance and the proportion of natural refuge have a much greater effect.ConclusionsWe concluded that planting the first generation Bt cotton with Bt maize could significantly increase the risk of CBW resistance to Bt toxins as compared to planting a pyramid two-toxin Bt cotton. The strategies for reducing the risk of CBW resistance include replacing the one-toxin Bt cotton with a pyramid two-toxin Bt cotton, adopting a pyramid two-toxin Bt maize, and maintaining a sufficient proportion of natural refuges.

Susceptibility of Different Instars of Striacosta albicosta (Lepidoptera: Noctuidae) to Vip3A, a Bacillus thuringiensis (Bacillaceae: Bacillales) Protein

2019 ◽  
Vol 112 (5) ◽  
pp. 2335-2344 ◽  
Author(s):  
Yasmine Farhan ◽  
Jocelyn L Smith ◽  
Arthur W Schaafsma
Keyword(s):  
Bacillus Thuringiensis ◽  
Resistance Management ◽  
High Dose ◽  
Transgenic Corn ◽  
Resistance Development ◽  
Significant Difference ◽  
Survival And Development ◽  
Important Pest ◽  
Striacosta Albicosta ◽  
Lepidoptera Noctuidae

Abstract Striacosta albicosta (Smith) (Lepidoptera: Noctuidae) is an important pest of corn, Zea mays L. in the Great Lakes region, which can be controlled by transgenic corn expressing Vip3A protein from Bacillus thuringiensis. To inform insect resistance management, the susceptibility, survival, and development of first, third, and fifth instar S. albicosta to Vip3A was determined using protein-overlay and corn tissue bioassays. Tissue bioassays were also used to determine the quantity of corn tissues with and without Vip3A-expression consumed by various instars. In diet bioassays, third and fifth instars were significantly less susceptible to Vip3A compared with first instars; however, no significant difference was observed in susceptibility of older instars. In tissue bioassays, survival was lowest for larvae fed Vip3A-expressing tissues, ranging from 0 to 21%, however, developmental measures of larvae fed Vip3A-expressing tissues did not differ from those fed artificial diet or tissues of other Bt events. Consumption of Vip3A × Cry1Ab tissues did not differ from that of Cry1Ab for each instar. Estimated Vip3A exposure of first instars ranged from 3 to 57 times higher than the concentration required for 99% mortality (LC99) based on the product of the reported Vip3A expression in transgenic corn tissues and the consumption observed in tissue bioassays; however, the estimated exposure of third and fifth instars to Vip3A was lower than their respective LC99. These findings suggest that first instar S. albicosta maybe exposed to a high dose of Vip3A under field conditions; however, Vip3A-expression in corn may not be high dose against older instars, increasing the risk of resistance development.

scholarly journals Larval Migration Behaviour of Busseola fusca (Lepidoptera: Noctuidae) on Bt and Non-Bt Maize under Semi-Field and Field Conditions

Insects ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 16 ◽  
Author(s):  
Andri Visser ◽  
Hannalene Du Plessis ◽  
Annemie Erasmus ◽  
Johnnie van den Berg
Keyword(s):  
Plant Growth ◽  
Growth Stage ◽  
Plant Density ◽  
Busseola Fusca ◽  
Effective Control ◽  
High Dose ◽  
Bt Maize ◽  
Larval Migration ◽  
Migration Behaviour ◽  
Lepidoptera Noctuidae

Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is a destructive pest of maize throughout the African continent. Bt maize is an effective control measure for this pest, however, selection pressure for resistance evolution is high. This necessitates the implementation of insect resistance management (IRM) strategies such as the high-dose/refuge strategy. This IRM strategy relies on the validity of several assumptions about the behaviour of pests during insect-hostplant interactions. In this study, the migration behaviour of B. fusca larvae was evaluated in a semi-field (greenhouse) and field setting. The effect of factors such as different Cry proteins, plant growth stage at infestation, and plant density on the rate and distance of larval migration were investigated over four and five week periods. Migration of the larvae were recorded by using both a leaf feeding damage rating scale and destructive sampling at the end of the trials. Results indicated that B. fusca larval migration success was significantly affected by plant growth stage and plant density—while limited larval migration was recorded in plots inoculated with larvae at a late growth stage (V10), higher plant density facilitated increased interplant migration. The results also suggest that B. fusca larvae do not migrate extensively (rarely further than two plants from the natal plant) and that larval mortality is high. Implications for IRM strategies are discussed.

Resistance to Bt Maize in Busseola fusca (Lepidoptera: Noctuidae) From Vaalharts, South Africa

2011 ◽  
Vol 40 (2) ◽  
pp. 477-483 ◽  
Author(s):  
M. Kruger ◽  
J.B.J. Van Rensburg ◽  
J. Van Den Berg
Keyword(s):  
South Africa ◽  
Busseola Fusca ◽  
Bt Maize ◽  
Lepidoptera Noctuidae

Resistance Risk Evaluated by Metaflumizone Selection and the Effects on Toxicities Over Other Insecticides in Spodoptera exigua (Lepidoptera: Noctuidae)

2019 ◽  
Vol 112 (5) ◽  
pp. 2354-2361
Author(s):  
Xing-Xing Sun ◽  
Hong-Yang Li ◽  
Ying-Jie Jiang ◽  
Jun-Xi Zhang ◽  
Hui-Ling Gu ◽  
...  
Keyword(s):  
Spodoptera Exigua ◽  
Channel Blocker ◽  
Resistance Management ◽  
Cross Resistance ◽  
Realized Heritability ◽  
Sodium Channel Blocker ◽  
Resistance Risk ◽  
Resistance Evolution ◽  
Threshold Trait ◽  
Lepidoptera Noctuidae

Abstract Metaflumizone is a novel semicarbazone insecticide. It functions as a sodium channel blocker insecticide (SCBI) with excellent insecticidal activity on most economically important lepidopterous pests. This study assessed the resistance risk of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) to metaflumizone in the laboratory and the effects of metaflumizone selection on toxicities to other insecticides. Spodoptera exigua collected from a field population at Huizhou in 2012 were successively challenged by metaflumizone to evaluate the risk of resistance evolution. Twelve generations of selection increased resistance to metaflumizone by 3.4-fold and threshold trait analysis revealed that the realized heritability (h2) of this resistance was 0.086. When h2 was equal to 0.086 and 90% of individuals were killed at each generation, LC50 to metaflumizone increased by 10-fold after 15 generations. The selection by metaflumizone did not increase the resistance to indoxacarb, chlorantraniliprole, spinosad, methomyl, or endosulfan, suggesting a lack of cross-resistance. However, metaflumizone challenge upheld the recession of resistance to emamectin benzoate, chlorfluazuron, and tebufenozide. The block of resistance drops by metaflumizone exposure implied a possible cross-resistance between metaflumizone and these three insecticides. These results contribute to integrated resistance management of S. exigua.

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