Resistance development in mosquito larvae Culex pipiens to the bacterial agent Bacillus thuringiensis var. israelensis

2003 ◽  
Vol 127 (1) ◽  
pp. 29-32 ◽  
Author(s):  
M. S. Saleh ◽  
F. A. El-Meniawi ◽  
N. L. Kelada ◽  
H. M. Zahran
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Mosquito Larvae ◽  
Resistance Development ◽  
Bacterial Agent

scholarly journals Resistance Development to Diflubenzuron and Bacillus Thuringiensis Subsp. Israelensis of Culex Pipiens f. Pipiens and Culex Pipiens f. Molestus (Diptera: Culicidae) and its Effects on Their Winter Survival

2020 ◽  
Author(s):  
Charalampos Ioannou ◽  
Christos Hadjichristodoulou ◽  
Maria A. Kyritsi ◽  
Nikos T. Papadopoulos
Keyword(s):  
Bacillus Thuringiensis ◽  
Culex Pipiens ◽  
Survival Rates ◽  
Larval Survival ◽  
Winter Survival ◽  
World Health ◽  
Winter Period ◽  
Fitness Costs ◽  
Resistance Development ◽  
High Dependency

Abstract Background: The Culex pipiens mosquito consists of two forms named pipiens and molestus that exhibit substantial differences in their biology including overwintering behavior. Diflubenzuron (DFB) and Bacillus thuringiensis subsp. israelensis (Bti) are among the most widely used larvicides for controlling Cx. pipiens populations. The high dependency on these two larvicides, pose major concerns for resistance development. The evolution and stability of resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions such as the winter period. The aim of the present study was to explore the resistance development of pipiens and molestus forms to both larvicides and its potential fitness costs on their winter survival.Methods: Colonies of both forms of Cx. pipiens were established from the same area. Following the World Health Organization protocols (WHO), the efficacy of both larvicides was determined for each mosquito population. Then, larvae from each form were selected for three successive generations by applying fixed doses corresponding to IE80 (IE: Inhibition of adult Emergence) and LC80 (LC: Lethal Concentration) for DFB and Bti respectively. At the end of this process, the resistance levels and the winter survival of the selected populations relative to controls (colonies that received no selection) were determined.Results: Contrary to Bti, selection with DFB induced different levels of resistance between the two forms of Cx. pipiens. The selected populations of Cx. pipiens f. molestus to both larvicides exhibited a high fitness cost in terms of reduced winter larval survival rates relative to control. Moreover, the obtained adults of the Bti selected population experienced significantly shorter lifespan compared to control and DFB selected population. On the other hand, selection with both DFB and Bti had no apparent effects on Cx. pipiens f. pipiens female winter survival rates relative to control. Furthermore, the reproductive parameters and the longevity of the overwintered females were similar between the selected populations and the control. Conclusions: Our findings are expected to contribute on the better understanding of the resistance development and evolution of the two forms of Cx. pipiens to DFB and Bti allowing the adoption of appropriate resistance management strategies.

scholarly journals Preliminary studies for the attract-and-kill strategy against Culex pipiens

2017 ◽  
Vol 17 ◽  
pp. 3 ◽  
Author(s):  
E. Kioulos ◽  
G. Koliopoulos ◽  
E. A. Couladouros ◽  
A. Michaelakis
Keyword(s):  
Bacillus Thuringiensis ◽  
Growth Regulator ◽  
Culex Pipiens ◽  
Mosquito Species ◽  
Insect Growth Regulator ◽  
Mosquito Larvae ◽  
Synthetic Pheromone ◽  
Attract And Kill ◽  
Gravid Females ◽  
Microbial Agent

The attract-and-kill strategy requires an intelligent and an efficient combination of an attractant and a killing agent such as a pheromone and an insecticide respectively. The production of the synthetic oviposition pheromone of the mosquito species Culex quinquefasciatus (Diptera: Culicidae) was already achieved and its combination with three different insecticides were tested. Furthermore three larvicides, an insect growth regulator (pyriproxyfen), an organophosphate (temephos) and a microbial (Bacillus thuringiensis subsp. israelensis) were tested in the laboratory against Culex pipiens biotype molestus (Diptera: Culicidae) as agents that can keep water free from mosquito larvae. Larvicidal activity, over a 50-day period, revealed good results primary for temephos and secondary for pyriproxyfen. Temephos killed all the hatched larvae (100%) while pyriproxyfen was effective the first five days (>90%) and for the following days mortality was in a rate between 60 and 80%. The results from oviposition bioassays revealed that except temephos all the tested larvicidals repel gravid females of laying eggs for the first two days. However, when synthetic pheromone is combined with the three larvicidals, temephos and microbial agent followed the same attractant pattern as synthetic pheromone independently.

scholarly journals Cloning and Expression of Two Crystal Protein Genes, cry30Ba1 and cry44Aa1, Obtained from a Highly Mosquitocidal Strain, Bacillus thuringiensis subsp. entomocidus INA288

2006 ◽  
Vol 72 (8) ◽  
pp. 5673-5676 ◽  
Author(s):  
Takeshi Ito ◽  
Tomonori Ikeya ◽  
Ken Sahara ◽  
Hisanori Bando ◽  
Shin-ichiro Asano
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Culex Pipiens ◽  
Crystal Protein ◽  
Cloning And Expression ◽  
Culex Pipiens Pallens ◽  
Bacillus Thuringiensis Subsp ◽  
Pipiens Pallens ◽  
Crystal Protein Genes

ABSTRACT Two novel crystal protein genes, cry30Ba and cry44Aa, were cloned from Bacillus thuringiensis subsp. entomocidus INA288 and expressed in an acrystalliferous strain. Cry44Aa crystals were highly toxic to second-instar Culex pipiens pallens (50% mortality concentration [LC50] = 6 ng/ml) and Aedes aegypti (LC50 = 12 ng/ml); however, Cry30Ba crystals were not toxic.

scholarly journals Effects of two formulations based on Bacillus thuringiensis subsp. israelensis on Aedes aegypti mosquito larvae under laboratory conditions

2008 ◽  
Vol 23 (4) ◽  
pp. 251-258
Author(s):  
Milenka Peric ◽  
Mirjana Prijovic ◽  
Goran Andric
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Aqueous Suspension ◽  
Pure Water ◽  
Clay Content ◽  
Experimental Period ◽  
Mosquito Larvae ◽  
Water Dispersible ◽  
Bacillus Thuringiensis Subsp ◽  
Zero Time

Toxicity and persistence of two formulations based on Bacillus thuringiensis subsp. israelensis applied to Aedes aegypti mosquito larvae were tested under laborabory conditions. The formulations were: a) water dispersible granules (product VectoBac WDG), and b) aqueous suspension (product VectoBac 12AS). The effects of both products on mosquito larvae were tested immediately after their dilution in pure water (zero time) and in 1-, 2-, 8- and 13-day old solutions. The two products were also tested in mixtures of water and clay at a rate of 0.5 g clay/150 ml water immediately after product dilution, and in one-day old solutions containing 0.1 and 0.05 g of clay in the same amount of water. The product VectoBac WDG was persistent and highly effective against Ae. aegypti larvae in pure water after the longest experimental period of 13 days, and significantly more effective than VectoBac 12AS at equal rates of application. The effectiveness of VectoBac 12AS weakened significantly after 8 and 13 days of treatment, compared to the effects at zero time and in 1- and 2-day old solutions. High clay content in water significantly reduced the larvicidal effectiveness of both products, indicating its possible compromising role during product application in practice.

Friendly Foes: The Bio-control Agents

2018 ◽  
Vol 2 (01) ◽  
Author(s):  
Kalpana Singh
Keyword(s):  
United States ◽  
Biological Control ◽  
Bacillus Thuringiensis ◽  
United States Of America ◽  
Control Agent ◽  
Mosquito Larvae ◽  
Bt Cotton ◽  
Economic Threshold ◽  
Pest Population ◽  
Natural Way

The bio-control agents are those organisms that manage the pest population in natural way and keep them below the economic threshold and are thus applied by the agency of man. This process is known as bio-control or biological control. They are foes to the pests and are thus beneficial and a friend for us. There are many pathogens (Bacillus thuringiensis, Bt cotton), parasites (parasitoids, ex. Parasitic wasps, tachinid flies) and predators (ex. Gambusia fish against mosquito larvae) that can be applied as bio-control agents. Many are being used as effective pest control agent in Europe and United States of America. There is lots of potential in this field and more explorations and researches need to be done in an agricultural country like India.

scholarly journals Effects of Propoxur Exposure on Insecticidal Susceptibility and Developmental Traits in Culex pipiens quinquefasciatus

Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 288
Author(s):  
Xiaolei Zhang ◽  
Samuel Karungu ◽  
Quanxin Cai ◽  
Zhiming Yuan ◽  
Xiaomin Hu
Keyword(s):  
Culex Pipiens ◽  
Constitutive Expression ◽  
Adult Survivors ◽  
Lethal Concentration ◽  
P450 Monooxygenase ◽  
Resistance Development ◽  
Culex Pipiens Quinquefasciatus ◽  
Rate Of Increase ◽  
Developmental Traits ◽  
Net Reproduction

Propoxur-sel strains of Culex pipiens quinquefasciatus were derived from a lab-bred strain following 16 generations of propoxur exposure under sublethal concentrations of LC25 (lethal concentration of 25%) and LC50 (lethal concentration of 50%), respectively. This resulted in resistance development in F16 with ratios of 8.8× and 6.3×, respectively, compared with F0. The fecundity, longevity, sex ratio (F/M), and hatchability of the propoxur-exposed Cx. quinquefasciatus adult survivors and their offspring were decreased, with no effect on the emergence ratio and pupa survival rate. In addition, the intrinsic rates of increase (r), the net reproduction (R0), and the finite rate of increase (λ) of the Cx. quinquefasciatus offspring generations were also decreased significantly compared to F0. Correspondingly, the mean generation time (T) and the population double time (DT) in propoxur-sels were increased. Enhanced activities of cytochrome P450 monooxygenase and esterase were also observed in propoxur-sels, indicating that a detoxification mechanism might be responsible for resistance development in Cx. quinquefasciatus. Except for the three genes cyp4d42v1, cyp4c52v1, and cyp6aa9 which displayed a coincidence in some degree in different treatments, induction by different doses of propoxur and constitutive expression in different generations of propoxur-sel strains resulted in an inconsistent identification of the P450 genes probably related with resistance.

scholarly journals Delivery Methods for RNAi in Mosquito Larvae

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Kashif Munawar ◽  
Azzam M Alahmed ◽  
Sayed M S Khalil
Keyword(s):  
Mosquito Control ◽  
Mosquito Species ◽  
Main Tool ◽  
Field Application ◽  
World Population ◽  
Mosquito Larvae ◽  
Health Issues ◽  
Delivery Methods ◽  
Resistance Development ◽  
The World

Abstract Mosquito-transmitted diseases pose a threat for a great portion of the world population. Chemical insecticides are the main tool for mosquito control. Heavy dependence on chemicals created several problems such as resistance development in many mosquito species, environmental effects, and human health issues. Other tools for mosquito control were developed and used in some parts of the world. Ribonucleic acid interference (RNAi) is a reverse genetic mechanism that was recently introduced as a new tool for pest control. Regarding mosquito, RNAi was used to study gene function and to discover genes that can be used as targets for control purposes. Several delivery methods are used to induce RNAi in mosquito larvae. Some methods such as injection and soaking are used routinely in RNAi research but have no application in the field. Other methods such as nanoparticles and microbes have some characteristics that make them good candidates for field application. In this report, we will focus on delivery methods for RNAi in mosquito larvae and will give examples for each method.

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