VideoTrack Insect / Parasite

PUBLICATIONS

Azadirachtin-mediated reproductive response of the predatory pirate bug Blaptostethus pallescens

BioControl, July 2014

2014-08-05

ABSTRACT

Insecticides can have lethal or sublethal effects upon targeted pest species, and sublethal effects may even favor pest outbreaks if insecticide-induced hormesis occurs. Hormesis is a biphasic dose—response of a given chemical compound that is stimulatory at low doses and toxic at high doses. The former response may result from the disruption of animal homeostasis leading to trade-off shifts between basic ecophysiological processes. A growing interest in the use of biorational insecticides, such as azadirachtin to control stored-product pests, raises concerns about potential sublethal effects. In this study, we explored the hypothesis that azadirachtin can negatively impact the reproductive capacity of the Mexican bean weevil, Zabrotes subfasciatus (Boheman) (Chrysomelidae: Bruchinae), a key pest of stored beans. In addition,weinvestigated whether adults of this species could compensate for any sublethal effect that might have affected any of their reproductive parameters by adjusting the allocation of its reproductive efforts. The results showed that females of Z. subfasciatus increased fecundity daily to compensate for azadirachtin-induced decreased longevity. In addition, a stage-structured matrix study revealed that populations of Z. subfasciatus engendered from females exposed to azadirachtin exhibited a higher rate of population increase (r) and a higher net reproductive rate (Ro). Finally, a projection matrix analysis showed notably higher densities along the generations for azadirachtin-exposed Z. subfasciatus populations. Thus, our study provides empirical evidence for the capacity of Z. subfasciatus to adapt to sublethal effects caused by biorational insecticides; consequently, this study highlights the importance of understanding this phenomenon when devising pest management strategies.

Azadirachtin-mediated reproductive response of the predatory pirate bug Blaptostethus pallescens

This publication was made using the VideoTrack Insect / Parasite

Age-mediated and environmentally mediated brain and behavior plasticity in the stingless bee Melipona quadrifasciata anthidioides

2015-02-01

Abstract

Structural changes in the insect brain related to age and individual experience may underlie the behavioral plasticity that is particularly important in such social insects as bees. This study assessed the influence of age and rearing conditions (field vs laboratory) in mediating changes in the volume of mushroom bodies and antennal lobes in the brains of workers of the native stingless beeMelipona quadrifasciata anthidioides Lepeletier, a pollinator species with small colonies exhibiting high level of sociability and behavioral versatility. Although only age-dependent enlargement was observed in the antennal lobes, significant increase (21 %) in the neuropils of the mushroom bodies occurred before the foraging age, in contrast to honeybees, and environmental complexity led to a significant increase in both the mushroom body volume and the walking activity. Such differences in the stingless bee M. quadrifasciata anthidioides as compared with the honeybee may assist in relating brain evolution and plasticity with the behavior in these social insects.

Age-mediated and environmentally mediated brain and behavior plasticity in the stingless bee Melipona quadrifasciata anthidioides

Hudson Vaner V. Tomé, Conrado A. Rosi-Denadai, Jessica Fernanda N. Pimenta, Raul Narciso C. Guedes, Gustavo F. Martins

Daily and Seasonal Extranidal Behaviour Variations in the Invasive Yellow-Legged Hornet, Vespa velutina Lepeletier (Hymenoptera: Vespidae)

Journal of Insect Behavior

2017-03-10

Abstract


In eusocial insect species, the nest represents the fundamental element of the colony. Extranidal activities (foraging, nest maintenance, defence) are fundamental for the development and the survival of the colony. Therefore, they may represent interesting targets to disrupt to limit their expansion in case of pest species such as Vespa velutina, an alien predator of domestic honeybees in Europe. An accurate knowledge of the pattern of activity of this pest’s colonies is therefore required. Due to the highly defensive nature of this hornet, a video monitoring was realized on two colonies during their growth from August to November. Three major behaviours were monitored: nest maintenance, patrolling on the nest and foraging flights. Although of different size and monitored during different years, the two colonies exhibited similar patterns of daily and seasonal variation. This work is a first step in the study of this pest especially in view of control program.

 

http://link.springer.com/article/10.1007/s10905-017-9607-3

Survival and Locomotory Behavior of Earwigs After Exposure to Reduced-Risk Insecticides

Journal of Economic Entomology

2017-05-12

Abstract

The conservation of natural enemies is an important tactic to promote biological control of arthropod pests. The earwig Doru luteipes (Sccuder) is the most important predator of the fall armyworm Spodoptera frugiperda (J.E. Smith) in corn fields. One way of conserving these predators in the field is by using only selective insecticides when the pest population reaches the economic threshold. Some recent insecticides such as azadirachtin, chlorantraniliprole, and novaluron have been claimed to pose reduced risk for natural enemies. Nevertheless, there is a dearth of information regarding the selectivity of these insecticides upon earwigs in specific. In this study, we carried out a series of laboratory assays to examine the survivorship and locomotory behavior of D. luteipes after exposure to fresh dry residue of azadirachtin, chlorantraniliprole, and novaluron. Our results show a significant survival reduction for D. luteipes nymphs exposed to fresh residues of chlorantraniliprole and novaluron. In the behavioral studies, adults of D. luteipes stopped more often, spent more time resting (inactive), and moved more slowly immediately after exposure to chlorantraniliprole residue. These results suggest that chlorantraniliprole may mediate an impaired movement and a behavior arrestment of earwigs after contact with this insecticide fresh residue. This could translate into reduced foraging efficiency, and increase exposure and insecticide uptake. Although chlorantraniliprole and novaluron showed a potential to undermine the biological control provided by earwigs, it is yet essential to conduct field trials in order to confirm our laboratory results.

 

https://academic.oup.com/jee/article-abstract/doi/10.1093/jee/tox137/3821189/Survival-and-Locomotory-Behavior-of-Earwigs-After

How Apis mellifera Behaves with its Invasive Hornet Predator Vespa velutina?

Journal of Insect Behavior

2017-12-30

Abstract

Invasive species are now recognized as a major cause of native biodiversity loss worldwide. In the current deleterious context for pollinators, the invasive yellow-legged hornet, Vespa velutina, represents an additional threat to the domestic honeybee, Apis mellifera, in Europe. Therefore, understanding the impact of this predator on honeybee colonies is of major importance. In the present study, we tried to assess the impact of V. velutina on the honeybee foraging and defence behaviour based on the video monitoring of two hives. Balling behaviour is reported here for the first time under natural conditions in A. mellifera against V. velutina in Europe. Although these results are preliminary and should be carefully considered, we found that the number of hornets impacted honeybee foraging and defence behaviours. More defensive behaviours were notified in the hive, which survives slightly longer. This may suggest that selecting for more defensive colonies may provide an interesting perspective.

Acknowledgements

This research project was funded by a FranceAgriMer [grant #797/2007–2010]. Second author was also supported by a grant from the Fondation pour la Recherche sur la Biodiversité [Wasprey project]. Financial support was also provided by CNRS, IRD and INRA SPE department core budgets. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Conceived and designed the experiments: MA, GA. Performed the experiments: KM, MA, LL, OB, GA. Analyzed the data: KM, LL, DT. Contributed reagents/materials/analysis tools: KM, MA, OB, GA, DT. Wrote the paper: KM, DT.

Toxicity and sublethal effects of allyl isothiocyanate to Sitophilus zeamais on population development and walking behavior

Journal of Pest Science

2018-01-23

Abstract

Essential oils and their derivatives have been suggested as promising alternatives for the control of insect pests. However, the potential sublethal effects of these substances on insects can contribute to the development of resistance strategies that could compromise its control. This study aimed to evaluate the toxicity of allyl isothiocyanate (AITC) on adults of five populations of Sitophilus zeamais (Coleoptera: Curculionidae). The effects of sublethal doses of AITC on the locomotor behavior and development of the insect population were also evaluated. The AITC toxicity was determined by a bioassay for lethal concentrations, wherein the mortality curves were established using increasing concentrations of AITC ranging from 0.5 to 10.0 μL L−1. The locomotor behavior was evaluated by distance walked, walking velocity and resting time. In addition, the daily and cumulative emergencies for all populations were evaluated. The LC50 found indicated a uniform susceptibility among the populations studied, without any indication of resistance to the AITC. All populations of S. zeamais had their population growth rates affected by sublethal exposure to AITC, presenting delayed accumulated emergence and a reduction up to 80.9% in the daily emergence. Although differences have been observed in the pattern of walking of the populations, treatment with AITC did not influence their locomotor behavior. The results indicate a lower risk of resistance development in the short term, suggesting that AITC can be a potential alternative for the control of S. zeamais on stored products.

https://link.springer.com/article/10.1007/s10340-017-0950-0

Imidacloprid resistance in the Neotropical brown stink bug Euschistus heros: selection and fitness costs

Journal of Pest Science

2018-09-28

Abstract

Neonicotinoid insecticides (e.g., imidacloprid) are some of the most prevalent tools used to control hemipterans that attack soybean crops worldwide. However, the emergence of neonicotinoid-resistant strains of phytosuccivorous soybean pests, such as the Neotropical brown stink bug Euschistus heros, has posed a challenge to the sustainable use of these compounds. Here, we laboratory-selected two E. heros strains for imidacloprid resistance and evaluated the activity of detoxification enzymes (e.g., cytochrome P450, esterases and glutathione-S-transferases) as well as potential adaptive costs associated with resistance (e.g., in survival, fecundity and fertility) in both strains, while laboratory selection for 13 generations in a known imidacloprid-susceptible E. heros strain (ImiSusc) resulted in an imidacloprid-resistant strain (ImiLabSel) with a resistance ratio (RR) of 11.6; similar resistance levels (i.e., RR = 13.5) were also achieved in another imidacloprid-resistant strain, which was field-collected (ImiGoias) and laboratory-selected for only six generations (ImiRes). Regarding enzymatic activity, both resistant strains differed from the imidacloprid-susceptible strain only in the activity of cytochrome P450, where the ImiLabSel and ImiRes strains exhibited higher activity by 72.3% and 40.5%, respectively. Furthermore, severe fitness costs (reductions of 86% for ImiLabSel and 68.0% for ImiRes) were recorded in both imidacloprid-resistant strains. Collectively, our results showed that E. heros rapidly responded to laboratory selection for neonicotinoid resistance, with enhanced cytochrome P450 activity as the likely underlying mechanism, and that they exhibit associated fitness costs, which have direct implications for the management of this insect pest.

 

Link to the publication :

https://link.springer.com/article/10.1007/s10340-018-1048-z

Glyphosate is lethal and cry toxins alter the development of the stingless bee Melipona quadrifasciata

Environmental Pollution

2018-10-03

Highlights

• Stingless bees pollinate some GM and conventional crops such as cotton and coffee.
• The herbicide glyphosate caused mortality in stingless bees larvae reared in vitro.
• Cry1F and Cry2Ab toxins caused delay in bee development.
• Cry toxins and glyphosate can impair colony growth and reduce pollination.

Abstract

Brazil is the second largest producer of genetically modified plants in the world. This agricultural practice exposes native pollinators to contact and ingestion of Bacillus thuringiensis proteins (e.g. Cry toxins) from transgenic plants. Furthermore, native bees are also exposed to various herbicides applied to crops, including glyphosate. Little is known about the possible effects of glyphosate and Cry proteins on stingless bees, especially regarding exposure at an immature stage. Here, we show for the first time that glyphosate is lethal, and that Cry toxins (Cry1F, Cry2Aa) alter the development of the stingless bee Melipona quadrifasciata upon contamination of larval food. Glyphosate was very toxic to the bee larvae, killing all of them within only a few days of exposure. Bees treated with Cry2Aa proteins had a higher survival rate and were delayed in their development, compared to the negative controls. Those treated with the Cry1F protein also suffered delays in their development, compared to the negative controls. In conclusion, the proteins Cry1F, Cry2Aa, and the herbicide glyphosate were highly toxic to the stingless bee M. quadrifasciata, causing lethal or sublethal effects which can severely impair colony growth and viability, and reduce pollination ability.

 

Link to the publication :

https://www.sciencedirect.com/science/article/pii/S0269749118325478

Diversity and convergence of mechanisms involved in pyrethroid resistance in the stored grain weevils, Sitophilus spp.

Scientific Reports

2018-11-05

Abstract

Target-site mutations and changes in insect metabolism or behavior are common mechanisms in insecticide-resistant insects. The co-occurrence of such mechanisms in a pest strain is a prominent threat to their management, particularly when alternative compounds are scarce. Pyrethroid resistance among stored grain weevils (i.e., Sitophilus spp.) is an example of a long-standing concern, for which reports of resistance generally focus on a single mechanism in a single species. Here, we investigated pyrethroid resistance in maize and rice weevils (i.e., Sitophilus zeamais and S. oryzae), exploring potential knockdown resistance (kdr) mutations in their sodium channels (primary site for pyrethroid actions) and potential changes in their detoxification and walking processes. Resistance in pyrethroid-resistant rice weevils was associated with the combination of a kdr mutation (L1014F) and increases in walking and detoxification activities, while another kdr mutation (T929I) combined with increases in walking activity were the primary pyrethroid resistance mechanisms in maize weevils. Our results suggest that the selection of pyrethroid-resistant individuals in these weevil species may result from multiple and differential mechanisms because the L1014F mutation was only detected in Latin American rice weevils (e.g., Brazil, Argentina and Uruguay), not in Australian and Turkish rice weevils or Brazilian maize weevils.

 

Introduction

The overuse of dichlorodiphenyltrichloroethane (i.e., DDT) up to the 1980’s and more recently of other synthetic insecticides (e.g., pyrethroids) for controlling stored product insect pests has contributed to the selection of insecticide-resistant strains, leading to severe economic losses in storage facilities worldwide. Regarding the pyrethroid insecticides, the resistance management is complicated because resistance occurs in a variety of forms, including reduced insecticide penetration, metabolic resistance (through detoxification enzymes), behavioral resistance and target-site alterations1,2. Although the pyrethroid insecticides exert their toxicity primarily by disrupting the function of the voltage-gated sodium channels in excitable cells3,4,5,6,7,8, these compounds also have secondary action targets (e.g., ionic imbalance and osmoregulatory dysfunction) that contribute to their activity9,10,11.

Multiple and distinct pyrethroid resistance mechanisms have been investigated in toxicological studies with focus on the contribution of the major mechanism, which includes target-site mutations (known as knockdown “kdr” resistance) and/or metabolic-based resistance12,13,14,15,16,17. The co-occurrence of distinct and multiple pyrethroid resistance mechanisms threatens resistance management strategies, with the threat particularly acute when alternative compounds are scarce, as is the case with stored grain weevils. Thus, it is essential to evaluate the potential of other classes of insecticides such as neonicotinoids, oxidiazines and spinosyns to control resistance populations of stored grain weevils.

Most of the losses in stored grains are caused by insect pests among which the grain weevils of the genus Sitophilus (e.g., the maize weevil Sitophilus zeamais Motsch. and the rice weevil Sitophilus oryzae L.) are particularly destructive18,19. The maize weevils, Sitophilus zeamais Motsch., and the rice weevil, Sitophilus oryzae L., are cosmopolitan and a major concern in tropical and subtropical regions, conditions that also occur in the Neotropical region20,21. Despite the economic importance of insecticide resistance in stored grain insect pests in general and grain weevils in particular22,23, studies on insecticide resistance are relatively limited for grain weevil species and do not usually explore the underlying molecular basis of the phenomenon24,25,26.

The mechanisms of pyrethroid resistance in the maize weevil S. zeamais as well as the fitness cost associated with it have been investigated20,25,27,28 but not those of the rice weevil. These studies with the maize weevil suggest that the primary resistance mechanism involves a single mutation in sodium channels (i.e., the kdr mutation T929I) that reduces the susceptibility to pyrethroids27, with secondary involvement of increased detoxification by glutathione-S-transferases28. However, this single mutation alone does not explain the high levels of resistance observed in maize weevil strains, and therefore, additional effort is required to understand the molecular basis of the resistance mechanisms involved in this species. The rice weevil is the subject of even greater neglect but also deserves attention because of the importance as a pest species and the relatively close phylogenetic relationship with the maize weevil29,30,31. Besides the resistance to insecticides resulting from the target site and metabolic alterations, other mechanisms associated with behavioral modification such as change in locomotory parameters have been reported in aphids32 and Sitophilus spp.33,34 but still need confirmation.

Thus, the present study was conducted to assess the physiological (e.g., occurrence of mutations in the sodium channel gene and activities of metabolic enzymes) and behavioral mechanisms (e.g., changes in walking patterns) of pyrethroid resistance in the maize and rice weevils (S. zeamais and S. oryzae, respectively). A series of toxicity, enzymatic, molecular and behavioral bioassays were conducted with a diverse and representative set of populations from both weevil species to achieve this objective. Our findings clearly demonstrated diversity and convergence of mechanisms involved in the pyrethroid resistance among strains of both species of grain weevils.

Results

Concentration-mortality bioassays

The probit model satisfactorily described the concentration-mortality data (goodness-of-fit tests exhibited low χ2-values [<9.5] and high P-values [>0.05]). The resistance ratios were estimated relative to the LD50 for the most susceptible strain for each insecticide (Tables 1 and 2). Based on the LD50 values obtained for the 14 maize weevil strains, the pyrethroid lambda-cyhalothrin and the neonicotinoid thiamethoxam were the most potent (i.e. lowest LD50 values) insecticides followed by the neonicotinoid imidacloprid and the spynosin spinosad (Table 1). Furthermore, the most susceptible maize weevil strain varied with insecticide. Individuals from E. S. Pinhal-SP were the most susceptible to both neonicotinoid insecticides (i.e., thiamethoxam and imidacloprid); while individuals from Teresina-PI (for the pyrethroid lambda-cyhalothrin) and Cristalina-GO (for the spynosin spinosad) were the most susceptible to other insecticides (Table 1). Regarding the pyrethroid insecticide lambda-cyhalothrin, and based on the 95% confidence intervals for resistance ratios (RR), five strains (total of 14) exhibited moderate to high resistance (i.e., RR > 5.0; Table 1). No resistance was found for spinosad, with the resistance ratios (RR) all below 2.8. Regarding the neonicotinoid insecticides, only three populations (Amambai-MS, Piracicaba-SP and Sao João-PR) exhibited (low) resistance levels to imidacloprid with resistance ratios (RR) between 2.7 and 3.6, while six populations (Amambai-MS, Balsas-MA, Ipojuca-PE, Jacarezinho-PR, Juiz de Fora-MG and Piracicaba-SP) exhibited low levels of thiamethoxam resistance (RR between 2.5 and 3.8). Generally, resistance to both neonicotinoids was either absent or very low among the strains tested.

Link to the publication :

https://www.nature.com/articles/s41598-018-34513-5

Walking activity and dispersal on deltamethrin- and spinosad-treated grains by the maize weevil Sitophilus zeamais

Crop Protection

2018-12-21

Highlights

• Deltamethrin and spinosad enhanced overall group activity of maize weevils.
• Deltamethrin, but not spinosad, significantly reduced walking by individual weevils.
• No insecticide irritability, nor repellence were detected.
• Weevils preferred the arena edges of untreated and deltamethrin-treated grains.
• Spinosad-exposed weevils dispersed evenly the arena, whereas those exposed to deltamethrin or unexposed were more at the edges.

Abstract

The maize weevil (Sitophilus zeamais) is a serious worldwide pest of stored products frequently requiring control measures to reduce its infestation and minimize grain losses. The fumigantphosphine and insecticides including pyrethroids and organophosphates have been the most used management tools against this stored product pest, but the over-reliance on these chemical products has led to insecticide resistance in maize weevil populations. A recent alternative, the actinomycete-based insecticide spinosad, has been considered highly effective against several stored grain pests, including maize weevils, and has sparked increasing attention. Nonetheless, the sublethal effects of spinosad have yet to be studied, particularly regarding its potential effect on insect dispersal within contaminated grain masses since exposure may be either enhanced or compromised. Thus, we carried out laboratory experiments using a digital tracking system and commercial insecticide formulations with the objective to assess if deltamethrin- or spinosad-contaminated grains may affect the walking activity and dispersal movements of adult maize weevils. The overall activity of groups of weevils was enhanced with insecticide exposure. However, insecticide exposure did not affect resting time and distance walked, but velocity and number of stops were affected compromising walking in individual walking bioassays. Insecticide avoidance by either irritability and repellence were not detected. Dispersal of adult maize weevils on treated grains differed among insecticidal treatments with individuals spending more time at the edges of arenas in non-treated and deltamethrin-treated grains. In contrast, insects on spinosad-treated grains were more evenly distributed within the arena. These findings reinforce the potential of spinosad as an alternative for managing maize weevils because this insecticide minimizes the risk of dispersal away from treated grains.

 

Link to the publication :

https://www.sciencedirect.com/science/article/pii/S0261219418303752

CoRest1 regulates neurogenesis in a stage‐dependent manner

Developmental Dynamics

2019-07-13

Abstract

Background

Developmental processes, including neuronal differentiation, require precise regulation of transcription. The RE‐1 silencing transcription factor (Rest), is often called a “master neuronal regulator” due to its large number of neural‐specific targets. Rest recruits CoRest (Rcor) and Sin3 co‐repressor complexes to gene regulatory sequences. CoRest not only associates with Rest, but with other transcription regulators. In this study, we generated zebrafish rcor1 mutants using transcription activator‐ like effector nucleases (TALENs), to study its requisite role in repression of Rest target genes as well as Rest‐independent Rcor1 developmental functions.

Results

While rcor1 mutants have a slight decrease in fitness, most survived and produced viable offspring. We examined expression levels of RE1‐containing genes in Maternal Zygotic rcor1 mutants (MZrcor1) and found that Rcor1 is generally not required for repression of Rest target genes at early stages. However, MZrcor1 mutants undergo more rapid neurogenesis compared to controls. We found that at gastrula stages, Rcor1 acts as a repressor of her gene family, but at later stages, many of these genes were increased in the MZrcor1 mutant.

Conclusions

Based on these findings, the central role of CoRest1 in neurogenesis is likely due to a Rest‐ independent role rather than as a Rest co‐repressor.

 

Link to the publication : https://onlinelibrary.wiley.com/doi/abs/10.1002/dvdy.86#

 

Drosulfakinin signaling in fruitless circuitry antagonizes P1 neurons to regulate sexual arousal in Drosophila

Nature Communications

2019-10-18

Abstract

Animals perform or terminate particular behaviors by integrating external cues and internal states through neural circuits. Identifying neural substrates and their molecular modulators promoting or inhibiting animal behaviors are key steps to understand how neural circuits control behaviors. Here, we identify the Cholecystokinin-like peptide Drosulfakinin (DSK) that functions at single-neuron resolution to suppress male sexual behavior in Drosophila. We found that Dsk neurons physiologically interact with male-specific P1 neurons, part of a command center for male sexual behaviors, and function oppositely to regulate multiple arousal-related behaviors including sex, sleep and spontaneous walking. We further found that the DSK-2 peptide functions through its receptor CCKLR-17D3 to suppress sexual behaviors in flies. Such a neuropeptide circuit largely overlaps with the fruitless-expressing neural circuit that governs most aspects of male sexual behaviors. Thus DSK/CCKLR signaling in the sex circuitry functions antagonistically with P1 neurons to balance arousal levels and modulate sexual behaviors.

 

Link to the publication : 

https://www.nature.com/articles/s41467-019-12758-6

Sigma-1 receptor is a key genetic modulator in amyotrophic lateral sclerosis

Human Molecular Genetics

2019-11-07

Abstract

Sigma-1 receptor (S1R) is an endoplasmic reticulum (ER) chaperone that not only regulates mitochondrial respiration but also controls cellular defense against ER and oxidative stress. This makes S1R a potential therapeutic target in amyotrophic lateral sclerosis (ALS). Especially, as a missense mutation E102Q in S1R has been reported in few familial ALS cases. However, the pathogenicity of S1RE102Q and the beneficial impact of S1R in the ALS context remain to be demonstrated in vivo. To address this, we generated transgenic Drosophila that expresses human wild-type S1R or S1RE102Q. Expression of mutant S1R in fly neurons induces abnormal eye morphology and locomotor defects in a dose-dependent manner. This was accompanied by abnormal mitochondrial fragmentation, reduced adenosine triphosphate (ATP) levels and a higher fatigability at the neuromuscular junction during high energy demand. Overexpressing IP3 receptor or glucose transporter mitigates the S1RE102Q-induced eye phenotype, further highlighting the role of calcium and energy metabolism in its toxicity. More importantly, we showed that wild-type S1R rescues locomotor activity and ATP levels of flies expressing the key ALS protein, TDP43. Moreover, overexpressing wild-type S1R enhances resistance of flies to oxidative stress. Therefore, our data provide the first genetic evidence that mutant S1R recapitulates ALS pathology in vivo while increasing S1R confers neuroprotection against TDP43 toxicity.

 

Link to the publication : 

https://academic.oup.com/hmg/advance-article-abstract/doi/10.1093/hmg/ddz267/5614191

Side effects of Bacillus thuringiensis on the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae)

Ecotoxicology and Environmental Safety

2019-11-21

Highlights

 

• Side effects of Bacillus thuringiensis (Bt) were evaluated on Palmistichus elaeisis, a parasitoid wasp of agricultural pest pupae.
• The Bt effects on parental and first-generation P. elaeisis parasitizing Bt-susceptible and -resistant Spodoptera frugiperda were investigated.
• Parental and first filial generation parasitoids emerged from Bt-treated S. frugiperda pupae showed lower survivorship than controls.
• Exposure to Bt reduced immature production and reproductive performance over the generations of the parasitoid.
• Results indicate low compatibility between the bioinsecticide agent and the parasitoid wasp.

 

Abstract

The endoparasitoid wasp Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) is used to control defoliating lepidopteran pests. Chemical insecticides are not compatible with natural enemies, but bioinsecticides, such as Bacillus thuringiensis Berliner (Bt), have great potential for use in integrated pest management. However, interactions between Bt and P. elaeisis still need to be investigated. This study aimed to evaluate the effects of Bt on parental and first-generation P. elaeisis parasitizing Bt-susceptible and -resistant Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). An additional aim was to determine the toxicity of Bt to susceptible third-instar S. frugiperda larvae. Larvae were exposed to lethal concentrations (LC50 and LC90) of Bt and then allowed to be parasitized by P. elaeisis. Parasitoid longevity, immature production, reproductive performance, and behavioral responses were evaluated. Bt repelled P. elaeisis and reduced immature production. Parental and first filial generation parasitoids of both sexes emerged from Bt-treated larvae showed lower survivorship than controls. Parasitoids had poorer reproductive performance in Bt-susceptible and -resistant pupae than in untreated pupae. Palmistichus elaeisis emerged from Bt-susceptible and -resistant S. frugiperda showed altered host-searching behavior and reproductive parameters, which indicates low compatibility between the bioinsecticide agent and the parasitoid wasp.

 

Link to the publication :

https://www.sciencedirect.com/science/article/abs/pii/S0147651319313090

Chemical constituents of tropical woods and resistance to the invasive drywood termite Cryptotermes brevis

Journal of Applied Entomology

2019-12-26

Abstract

Wood‐feeding, nesting and production of secondary reproductives are key determinant traits of invasive species of drywood termites, and the West Indian drywood termite Cryptotermes brevis (Walker) is one of their major examples of worldwide concern as pest species of structural lumber, furniture and other wood products. The problem and losses by this species are determined by the prevailing wood characteristics. However, despite the current widespread occurrence of this species in the tropics, except Asia, tropical wood resistance and underlying mechanisms of resistance against this termite are scarcely known. Nonetheless, wood hardness and particularly wood density were recently recognized as important underlying traits for C. brevis resistance in tropical woods, but the chemical wood constituents were not considered. Here, we assessed tropical wood resistance to the invasive termite species brevis and tested the relevance of their holocellulose, lignin and (total) extractive contents preventing termite infestation. Free‐choice and no‐choice tests were carried out in parallel with wood chemical characterization. Resistance to the West Indian termite varied with wood species in terms of both colonization and consumption, but only under free‐choice testing because without choice, no significant difference was detected among wood species. Regardless, none of these traits were significantly correlated with wood resistance to C. brevis . Therefore, wood physical resistance, particularly wood density, seems the main recognized determinant of tropical wood resistance against the West Indian drywood termite. The pattern of termite movement on the surface of soft, mid and hard wood was also consistent with this conclusion.

Link to the publication : 

https://onlinelibrary.wiley.com/doi/abs/10.1111/jen.12729

Selectivity of the botanical compounds to the pollinators Apis mellifera and Trigona hyalinata (Hymenoptera: Apidae)

2020-03-27

The toxicity of essential oils that can be used in insect pest management to pollinators needs further studies. Apis mellifera Linnaeus and Trigona hyalinata (Lepeletier) (Hymenoptera: Apidae) foragers were exposed by three pathways to ginger, mint, oregano and thyme essential oils to provide their LC50, LD50 and LC90, LD90. Oregano and thyme were more toxic through contact and topically for Amellifera while the toxicity of mint and ginger was lower. Trigona hyalinata was more tolerant to the essential oils than Amellifera. In the walking test, the area was treated (totally or partially) with sub-doses (LC50) obtained via contact. The area fully treated with oregano reduced the distance traveled and the movement speed increased the number of stops by Amellifera. Similar results were observed for Thyalinata with oregano and thyme oils. Apis mellifera showed irritability remaining shorter time in the area partially treated with ginger, mint and thyme essential oils while Thyalinata had similar behavior with ginger and thyme. Essential oils did not repel Amellifera or Thyalinata, but those of ginger, mint and thyme reduced the time spent by Amellifera in areas treated with sublethal doses. Oregano and thyme essential oils reduced the survival, mainly, of Amellifera, while ginger and mint were selective for both pollinators.

 

https://www.nature.com/articles/s41598-020-61469-2

Selectivity of the botanical compounds to the pollinators Apis mellifera and Trigona hyalinata (Hymenoptera: Apidae)

Nature

2020-06-04

The toxicity of essential oils that can be used in insect pest management to pollinators needs further studies. Apis mellifera Linnaeus and Trigona hyalinata (Lepeletier) (Hymenoptera: Apidae) foragers were exposed by three pathways to ginger, mint, oregano and thyme essential oils to provide their LC50, LD50 and LC90, LD90. Oregano and thyme were more toxic through contact and topically for A. mellifera while the toxicity of mint and ginger was lower. Trigona hyalinata was more tolerant to the essential oils than A. mellifera. In the walking test, the area was treated (totally or partially) with sub-doses (LC50) obtained via contact. The area fully treated with oregano reduced the distance traveled and the movement speed increased the number of stops by A. mellifera. Similar results were observed for T. hyalinata with oregano and thyme oils. Apis mellifera showed irritability remaining shorter time in the area partially treated with ginger, mint and thyme essential oils while T. hyalinata had similar behavior with ginger and thyme. Essential oils did not repel A. mellifera or T. hyalinata, but those of ginger, mint and thyme reduced the time spent by A. mellifera in areas treated with sublethal doses. Oregano and thyme essential oils reduced the survival, mainly, of A. mellifera, while ginger and mint were selective for both pollinators.

 

Link to the publication :

https://search.proquest.com/openview/228365b55e9898a879de807d24fcdb3c/1?pq-origsite=gscholar&cbl=2041939

Short- and long-term habituation of photonegative and exploratory responses in the flatworm planaria (Dugesia)

Apa Psycnet

2020-06-13

Abstract

Two experiments address the habituation of photonegative and exploratory responses in the flatworm planaria (Dugesia). Planarians possess a well-documented photonegative response; Experiment 1 showed that repeated exposures to a bright light source with short inter trial intervals (ITIs) within 1 experimental session gradually weakens the unconditioned photonegative response. In addition, it was found that presentation of an unexpected arousal-increasing stimulus (dropped water or a shock) temporarily re-establishes the photonegative response. Experiment 2 addressed the development of long-term habituation; we recorded the locomotor activity of the animals exposed to an inescapable bright light. Experiments 2A and 2B showed that planarians develop long-term habituation but only when they were trained in relatively novel contexts; when they were trained in familiar contexts (in surfaces similar to the ones in the home) the development of habituation was severely impaired. The results are discussed by reference to the theory of short- and long-term habituation put forward by Allan R. Wagner (Wagner, 1976), highlighting the impact that this theory has had in the research of invertebrate learning. (PsycInfo Database Record (c) 2020 APA, all rights reserved)

 

Link to the publication : 

https://psycnet.apa.org/record/2020-55131-012

Insecticidal and repellent activities of Cymbopogon citratus (Poaceae) essential oil and its terpenoids (citral and geranyl acetate) against Ulomoides dermestoides

Crop Protection

2020-07-03

Highlights

 

• The lethal and sublethal effects of lemongrass essential oil and their constituents were tested on the peanut beetle, Ulomoides dermestoides.
• The chemical analyses revealed 13 constituents to lemongrass essential oil being citral and geranyl acetate the main constituents in this essential oil.
• Lemongrass oil, citral, and geranyl acetate were toxic and reduce the survivorship of U. dermestoides at different doses.
• Lemongrass essential oil and their constituents exhibited significant effect to reduce the respiration rate and altering the locomotor activity.
• Lemongrass essential oil, citral, and geranyl acetate may represent valuable source of green insecticides to U. dermestoides.

 

Abstract

The peanut beetle, Ulomoides dermestoides Fairmaire (Coleoptera: Tenebrionidae), is a worldwide pest of stored grains. This study evaluated the toxicity and repellency of lemongrass (Cymbopogon citratus) essential oil and its components (citral and geranyl acetate) against U. dermestoides adults. Lethal doses (LD50 and LD90), survival rate, respiration rate, and repellent activity were determined. The major components of lemongrass essential oil were neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.5%). Lemongrass essential oil (LD50 = 5.17 μg insect−1), citral (LD50 = 4.17 μg insect−1), and geranyl acetate (LD50 = 7.21 μg insect−1) caused high contact toxicity in U. dermestoides adults. The survival rate was 99% in control insects, decreasing to 65.7% in insects exposed to the LD50 of lemongrass essential oil, 41.3% in insects treated with geranyl acetate, and 28.5% in those treated with citral. Insects exposed to lemongrass essential oil, geranyl acetate, or citral showed low respiration rates, reduced locomotor activity, and avoidance responses to treated surfaces. These findings demonstrate that lemongrass essential oil and its terpenoid components exhibit insecticidal and repellent activity against U. dermestoides, suggesting their potential for controlling this stored grain pest.

 

Link to the publication : 

https://www.sciencedirect.com/science/article/abs/pii/S0261219420302325

Short- and long-term habituation of photonegative and exploratory responses in the flatworm planaria (Dugesia)

Journal of Experimental Psychology: Animal Learning and Cognition

2020-08-03

Abstract

Two experiments address the habituation of photonegative and exploratory responses in the flatworm planaria (Dugesia). Planarians possess a well-documented photonegative response; Experiment 1 showed that repeated exposures to a bright light source with short inter trial intervals (ITIs) within 1 experimental session gradually weakens the unconditioned photonegative response. In addition, it was found that presentation of an unexpected arousal-increasing stimulus (dropped water or a shock) temporarily re-establishes the photonegative response. Experiment 2 addressed the development of long-term habituation; we recorded the locomotor activity of the animals exposed to an inescapable bright light. Experiments 2A and 2B showed that planarians develop long-term habituation but only when they were trained in relatively novel contexts; when they were trained in familiar contexts (in surfaces similar to the ones in the home) the development of habituation was severely impaired. The results are discussed by reference to the theory of short- and long-term habituation put forward by Allan R. Wagner (Wagner, 1976), highlighting the impact that this theory has had in the research of invertebrate learning. (PsycInfo Database Record (c) 2020 APA, all rights reserved)

 

Link to the publication : 

https://psycnet.apa.org/record/2020-55131-012

Endosymbiont load, personality and reproductive output of maize weevils (Sitophilus zeamais)

Journal of Pest Science

2020-09-22

Abstract

Endosymbiotic association is frequent in insects, and endosymbionts influence a range of biological processes in these organ-isms. The endosymbiont–insect association and interdependence allegedly result from random selection where ecological trade-offs take place and usually differ between the involved species. Insect behavior is potentially affected by this associa-tion, but the focus in such studies is symbiont presence rather than load, and overall behavioral patterns, not the individual set of integrated behavioral tendencies (i.e., individual personality). This knowledge gap limits the understanding of how the endosymbiont–insect association affects insect behavior and how this translates into fertility, as a measure of fitness. Here, we assessed the endosymbiont load of maize weevils [Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)], which hosts two symbiont species—Sodalis pierantonius and Wolbachia, and their association with weevil personality and reproductive consequences. Thus, individual female weevils were subjected to oral administration of antibiotics (ciprofloxa-cin and tetracycline) to secure a range of symbiont loads, which were quantified by qPCR. Individual personality of these females was recorded before and after endosymbiont suppression, and also that of their progeny. Female weevils maintained their personality with symbiont suppression, which was not transferred to their progeny. Nonetheless, personality itself was more important in determining female reproductive output than endosymbiont load, which did not significantly alter indi-vidual integrated behavior. Thus, management tactics targeting endosymbiont suppression may not be as effective as initially anticipated, unless complete suppression of the obligatory symbiont S. pierantonius takes place.

 

Link to the publication :

https://link.springer.com/article/10.1007/s10340-020-01287-7