Positive association between resistance to Bacillus thuringiensis and overwintering survival of cabbage loopers, Trichoplusia ni (Lepidoptera: Noctuidae)

2008 ◽  
Vol 98 (3) ◽  
pp. 317-322 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Positive Association ◽  
Pest Species ◽  
Development Of Resistance ◽  
Trade Offs ◽  
Major Pest ◽  
Selection For ◽  
Overwintering Survival ◽  
Lepidoptera Noctuidae

AbstractDevelopment of resistance to insecticides has generally been associated with fitness costs that may be magnified under challenging conditions. Lepidopterans which are resistant to the biopesticide Bacillus thuringiensis subsp. kurstaki (Btk) have been shown to have reduced fitness, such as lower survival when subjected to overwintering stress. Recently, resistance to Btk has been found in some populations of Trichoplusia ni Hübner in greenhouses in British Columbia. This situation provides an opportunity to investigate potential trade-offs between overwintering survival and insecticide resistance in a major pest species. Here, we assess the survival and eventual fecundity of Btk resistant and susceptible T. ni pupae exposed to cool temperatures. Contrary to our expectations, resistant T. ni had higher overwintering survival than susceptible individuals. This is the first account of a potential advantage associated with Btk resistance. Resistant and susceptible moths had reduced fecundity and smaller progeny after cold exposure compared to controls, and this may counteract the survival advantage. Nevertheless, it seems unlikely that this is sufficient to select out the resistant phenotype in the presence of strong selection for resistance and in the absence of immigration of susceptible moths. The appearance of resistance without evidence of a trade-off in overwintering survival presents a major challenge to management in production greenhouses.

scholarly journals Evaluation of Resistance Development in Bemisia tabaci Genn. (Homoptera: Aleyrodidae) in Cotton against Different Insecticides

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 996
Author(s):  
Muhammad Zaryab Khalid ◽  
Sohail Ahmed ◽  
Ibrahim Al-ashkar ◽  
Ayman EL Sabagh ◽  
Liyun Liu ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
The Other ◽  
Resistance Development ◽  
Susceptible Population ◽  
Low Level ◽  
Development Of Resistance ◽  
Major Pest ◽  
Selection For ◽  
High Level ◽  
Very High

Cotton is a major crop of Pakistan, and Bemisia tabaci (Homoptera: Aleyrodidae) is a major pest of cotton. Due to the unwise and indiscriminate use of insecticides, resistance develops more readily in the whitefly. The present study was conducted to evaluate the resistance development in the whitefly against the different insecticides that are still in use. For this purpose, the whitefly population was selected with five concentrations of each insecticide, for five generations. At G1, compared with the laboratory susceptible population, a very low level of resistance was observed against bifenthrin, cypermethrin, acetamiprid, imidacloprid, thiamethoxam, nitenpyram, chlorfenapyr, and buprofezin with a resistance ratio of 3-fold, 2-fold, 1-fold, 4-fold, 3-fold, 3-fold, 3-fold, and 3-fold, respectively. However, the selection for five generations increased the resistance to a very high level against buprofezin (127-fold), and to a high level against imidacloprid (86-fold) compared with the laboratory susceptible population. While, a moderate level of resistance was observed against cypermethrin (34-fold), thiamethoxam (34-fold), nitenpyram (30-fold), chlorfenapyr (29-fold), and acetamiprid (21-fold). On the other hand, the resistance was low against bifenthrin (18-fold) after selection for five generations. A very low level of resistance against the field population of B. tabaci, at G1, showed that these insecticides are still effective, and thus can be used under the field conditions for the management of B. tabaci. However, the proper rotation of insecticides among different groups can help to reduce the development of resistance against insecticides.

scholarly journals Genetic improvement of Bacillus thuringiensis against the cotton bollworm, Earias vitella (Fab.) (Lepidoptera: Noctuidae), to improve the cotton yield in Pakistan

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Fakhar-un-Nisa Yunus ◽  
Ghulam Raza ◽  
Rahat Makhdoom ◽  
Hafsa Zaheer
Keyword(s):  
Bacillus Thuringiensis ◽  
Growth Period ◽  
Crystal Protein ◽  
Cotton Bollworm ◽  
Vegetative Stage ◽  
Formulation Development ◽  
Major Pest ◽  
Important Cash Crop ◽  
Maximum Expression ◽  
Lepidoptera Noctuidae

AbstractIn the present study, CryIAc (Crystal protein) gene was cloned under Cry3A promoter, which is known to express vegetatively as a sporulation independent promoter, transformed into acrystalliferous strain of Bacillus thuringiensis. Its potential was evaluated as a strain to be used for formulation development against the spotted cotton bollworm Earias vitella (Fab.) (Lepidoptera: Noctuidae), the major pest of cotton, the important cash crop in Pakistan. The crystal protein produced in a new strain, i.e., Bt1, had comparable potency as of crystal protein produced during sporulation. The new strain Bt1 had the maximum expression of Cry1Ac protein during the vegetative stage, i.e., in the first 24 h, thereby reducing the growth period until crystal protein production, from 72 to 24 h. In addition, crystal protein produced during vegetative stage under Cry3A promoter remained encapsulated within the cells, which could protect them from UV degradation and was independent of sporulation; therefore; it did not produce spores and thus is not a source to spread Bt spores in the environment. It can, therefore, be called as an environmentally friendly pesticide to control cotton pest especially bollworms and ultimately improve the yield of cotton.

scholarly journals SELEÇÃO E CARACTERIZAÇÃO MOLECULAR DE BACILLUS THURINGIENSIS BERLINER COM ATIVIDADE TÓXICA PARA TRICHOPLUSIA NI HUEBNER (LEPIDOPTERA: NOCTUIDAE)

2010 ◽  
Vol 77 (4) ◽  
pp. 685-692
Author(s):  
E.D. Grecco ◽  
R.A. Polanczyk ◽  
D. Pratissoli
Keyword(s):  
Bacillus Thuringiensis ◽  
Trichoplusia Ni ◽  
Lepidoptera Noctuidae

RESUMO Trichoplusia ni é uma praga polífaga importante em plantios de crucíferas, soja e algodão. O presente estudo objetivou selecionar e caracterizar por método molecular isolados de Bacillus thuringiensis (Bt) com potencial para atuar com agentes de controle biológico de T. ni. Para os bioensaios de patogenicidade, uma alíquota com 3 x 108 esporos/mL de suspensão de Bt de cada isolado foi aplicada na superfície do disco de dieta artificial, previamente distribuída em placas de acrílico com 50 lagartas, distribuídas em 5 repetições. Nos bioensaios para a obtenção da CL50, apenas os isolados com 100% de mortalidade foram pré-selecionados, sendo testadas as seguintes concentrações: 102, 5 x 102, 103, 2 x 103, 4 x 103, 6 x 103, 8 x 103 esporos/mL, sendo os tratamentos compostos por 120 lagartas, distribuídas em 3 repetições. Foi feita caracterização molecular para detectar os genes cry1, cry2 e Vip para os isolados que obtiveram mortalidade acima de 95%. Os isolados HD-1 (Padrão), Bt-1043N-V, Bt-1034F, Bt-1009K, Bt-1000, Bt-969A causaram 100% de mortalidade nos testes de patogenicidade e CL50 de 1,17 x 103, 1,45 x 103, 1,46 x 103, 1,01 x 103, 9,43 x 102, 1,22 x 103, respectivamente. Não foram encontrados genes cry1, cry2 e Vip nos isolados testados, podendo outras toxinas Cry estar causando a mortalidade de T. ni, visto que os isolados testados são específicos para a ordem Lepidoptera. Estes isolados mostraram potencial para o controle de T. ni, sendo virulentos a este inseto, com potencial para serem utilizados em programa de manejo desta praga.

scholarly journals Shifts along the parasite–mutualist continuum are opposed by fundamental trade-offs

2019 ◽  
Vol 286 (1900) ◽  
pp. 20190236 ◽  
Author(s):  
Andrew C. Matthews ◽  
Lauri Mikonranta ◽  
Ben Raymond
Keyword(s):  
Bacillus Thuringiensis ◽  
Competitive Ability ◽  
Enterobacter Cloacae ◽  
Competitive Fitness ◽  
Host Protection ◽  
Nutrient Assimilation ◽  
Trade Offs ◽  
Host Growth ◽  
Selection For

Theory suggests that symbionts can readily evolve more parasitic or mutualistic strategies with respect to hosts. However, many symbionts have stable interactions with hosts that improve nutrient assimilation or confer protection from pathogens. We explored the potential for evolution of increased parasitism or decreased parasitism and mutualism in a natural gut symbiosis between larvae of Plutella xylostella and the microbe Enterobacter cloacae. We focused on interactions with the pathogen, Bacillus thuringiensis : selecting for parasitism in terms of facilitating pathogen infection, or increased mutualism in terms of host protection. Selection for parasitism led to symbionts increasing pathogen-induced mortality but reduced their competitive ability with pathogens and their in vitro growth rates. Symbionts did not evolve to confer protection from pathogens. However, several lineages evolved reduced parasitism, primarily in terms of moderating impacts on host growth, potentially because prudence pays dividends through increased host size. Overall, the evolution of increased parasitism was achievable but was opposed by trade-offs likely to reduce fitness. The evolution of protection may not have occurred because suppressing growth of B. thuringiensis in the gut might provide only weak protection or because evolution towards protective interactions was opposed by the loss of competitive fitness in symbionts.

scholarly journals Two new Brazilian isolates of Bacillus thuringiensis toxic to Anticarsia gemmatalis (Lepidoptera: Noctuidae)

2012 ◽  
Vol 72 (2) ◽  
pp. 363-369 ◽  
Author(s):  
LM. Fiuza ◽  
R. Schünemann ◽  
LMN. Pinto ◽  
MHB. Zanettini
Keyword(s):  
Bacillus Thuringiensis ◽  
Field Tests ◽  
Protein Crystals ◽  
Anticarsia Gemmatalis ◽  
Cry Genes ◽  
Velvetbean Caterpillar ◽  
Protein Fragments ◽  
Transmission Electron ◽  
Major Pest ◽  
Lepidoptera Noctuidae

Bacillus thuringiensis is a bacterium used for biopesticides production and pest-resistant plants due to the synthesis of protein crystals by cry genes, which are effective in controlling several insect orders such as Lepidoptera. This work aimed at the evaluation and characterisation of two new B. thuringiensis isolates active against A. gemmatalis (Hübner 1818) larvae, which is the soybean major pest. The results showed that Bt117-4 isolate amplified fragments corresponding to cry2 and cry9 genes, and synthesised protein fragments equivalent to 130, 90 and 45 kDa. The Bt3146-4 isolate amplified DNA fragments corresponding to cry9 gene and synthesised protein fragments of 70, 58 and 38 kDa. Transmission electron microscopy revealed the presence of protein crystals in both isolates. CL50 with Cry purified proteins from Bt117-4 and Bt3146-4, corresponded to 0.195 and 0.191 µg larvae-1, respectively. The two B. thuringiensis isolates selected in this study were effective to control velvetbean caterpillar at laboratory conditions. Field tests should be carried on to develop new biopesticides formulation as well for cry genes resource for Anticarsia gemmatalis resistant transgenic plants.

scholarly journals Evaluation of indigenous the nucleopolyhedrovirus (NPV) of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) in combination with chlorantraniliprole against Spodoptera species

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Ghulam Sarwar ◽  
Naeem Arshad Maan ◽  
Muhammad Ahsin Ayub ◽  
Muhammad Rafiq Shahid ◽  
Mubasher Ahmad Malik ◽  
...  
Keyword(s):  
Larval Mortality ◽  
Adult Emergence ◽  
Lethal Concentration ◽  
Pest Species ◽  
Vegetable Crops ◽  
Chemical Insecticide ◽  
Larval Instars ◽  
Novel Method ◽  
High Larval Mortality ◽  
Lepidoptera Noctuidae

Abstract Background The armyworms, Spodoptera exigua (Hübner), and S. litura (Fabricius) (Lepidoptera: Noctuidae) are polyphagous pests of many cash crops. Heavy crop losses have been reported for the fruit and vegetable crops each year owing to the diverse impact on global economies. The present study was aimed to sort out a novel method of pest control using the insect’s own nucleopolyhedrosis virus (NPV) alone and in combination with a new chemistry insecticide chlorantraniliprole. Results In the study, the effect of indigenous isolated nucleopolyhedrovirus (NPV) and the chemical insecticide (chlorantraniliprole) formulations against the 2nd and 4th larval instars of S. litura and S. exigua, collected from the different geographical region of Punjab (Pakistan) province, was evaluated. Three concentrations of the NPV isolate, sub-lethal (1 × 104, 6 × 104 POB ml−1), lethal (3 × 105 POB ml−1), and chlorantraniliprole 0.01 μl l−1, were applied alone and in combination against the 2nd and 4th larval instars of both pest species. The lethal concentration of NPV + chlorantraniliprole exhibited synergistic interaction and caused high larval mortality against both instars, while in all other combinations, additive effect was observed. Moreover, NPV + chlorantraniliprole at lethal concentration exhibited decreased pupation, adult emergence, and egg eclosion. Conclusion The implications of using NPV alone and in combination with an insecticide are discussed briefly in this study.

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