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Long-term effects of neonicotinoid insecticides on ants

Abstract
The widespread prophylactic usage of neonicotinoid insecticides has a clear impact on non-target organisms. However, the possible effects of long-term exposure on soil-dwelling organisms are still poorly understood especially for social insects with long-living queens. Here, we show that effects of chronic exposure to the neonicotinoid thiamethoxam on black garden ant colonies, Lasius niger, become visible before the second overwintering. Queens and workers differed in the residue-ratio of thiamethoxam to its metabolite clothianidin, suggesting that queens may have a superior detoxification system. Even though thiamethoxam did not affect queen mortality, neonicotinoid-exposed colonies showed a reduced number of workers and larvae indicating a trade-off between detoxification and fertility. Since colony size is a key for fitness, our data suggest long-term impacts of neonicotinoids on these organisms. This should be accounted for in future environmental and ecological risk assessments of neonicotinoid applications to prevent irreparable damages to ecosystems.

Schläppi, D., Kettler, N., Straub, L. et al. Long-term effects of neonicotinoid insecticides on ants. Commun Biol 3, 335 (2020). https://doi.org/10.1038/s42003-020-1066-2

https://www.nature.com/articles/s42003-020-1066-2
 

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Seek and you shall find: An assessment of the influence of the analytical methodologies on pesticide occurrences in honey bee-collected pollen with a systematic review

Highlights
• The analytical methodologies may underestimate the pesticide exposure on bees.
• Pesticide occurrence in pollen is negatively associated with the detection limit.
• In 4 pesticides, the detection limits were higher than their toxic doses.


Abstract
Honey bee mortality and colony losses have been reported worldwide. Although this phenomenon is caused by a combination of factors, agrochemicals have received special attention due to their potential effects on bees. In agricultural and urban environments bees are exposed to several compounds that may interact in unexpected ways, but information on the extent of pesticide exposure remains unclear. Several monitoring studies have been conducted to evaluate the field-realistic exposure of bees to pesticides after their release on the market. However, their outputs are difficult to compare and harmonize due to differences in the analytical methodologies and the sampling protocols (e.g. number of screened compounds and analysed samples, and detection limits (LODs)). Here, we hypothesize that the analytical methodologies used in the monitoring studies may strongly affect the pesticide occurrences in pollen underestimating the real pesticide exposure. By mean of a systematic literature review, we have collected relevant information on pesticide contaminations in the honey bee-collected pollen. Our findings showed that the pesticide occurrences were associated with the analytical methodologies and the real pesticide exposure has likely been underestimated in some monitoring studies. For four highly toxic compounds, the LOD used in these monitoring studies exceeded the doses that cause toxic effects on honey bees. We recommend that, especially for the highly toxic compounds, the LODs used in the monitoring studies should be low enough to exclude lethal or sublethal effects on bees and avoid “false negative” samples.


Gioele Toselli, Fabio Sgolastra; Seek and you shall find: An assessment of the influence of the analytical methodologies on pesticide occurrences in honey bee-collected pollen with a systematic review; Chemosphere; Volume 258, November 2020, 127358; https://doi.org/10.1016/j.chemosphere.2020.127358; https://www.sciencedirect.com/science/article/abs/pii/S0045653520315514
 

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Insecticides cause transcriptional alterations of endocrine related genes in the brain of honey bee foragers

Highlights
• Endocrine activities of pesticides can be assessed in honey bee foragers.

• Pesticides caused transcriptional alterations in brain and HPG indicative of endocrine activity.

• Chlorpyrifos showed strongest transcriptional alterations.

• Affected genes encode proteins involved in transition of nurse and forager bees.

• buffy and mrjp down-regulation and hbg3 and ilp1 up-regulation are potential endocrine indicators.

Abstract
Bees are exposed to endocrine active insecticides. Here we assessed expressional alteration of marker genes indicative of endocrine effects in the brain of honey bees. We exposed foragers to chlorpyrifos, cypermethrin and thiacloprid and assessed the expression of genes after exposure for 24 h, 48 h and 72 h. Chlorpyrifos caused the strongest expressional changes at 24 h characterized by induction of vitellogenin, major royal jelly protein (mrjp) 2 and 3, insulin-like peptide (ilp1), alpha-glucosidase (hbg3) and sima, and down-regulation of buffy. Cypermethrin caused minor induction of mrjp1, mrjp2, mmp1 and ilp1. The sima transcript showed down-regulation at 48 h and up-regulation at 72 h. Exposure to thiacloprid caused down-regulation of vitellogenin, mrjp1 and sima at 24 h, and hbg3 at 72 h, as well as induction of ilp1 at 48 h. The buffy transcript was down-regulated at 24 h and upregulated at 48 h. Despite compound-specific expression patterns, each insecticide altered the expression of some of the suggested endocrine system related genes.

Our study suggests that expressional changes of genes prominently expressed in nurse or forager bees, including down-regulation of buffy and mrjps and upregulation of hbg3 and ilp1 may serve as indicators for endocrine activity of insecticides in foragers.

Discussion
[...]
However, the importance of these findings lies in the fact that there is an expressional change of these gene transcripts per se. The here studied insecticides chlorpyrifos, cypermethrin and thiacloprid induce neurotoxicity by different modes of action. This makes it plausible that the insecticides also differ to some extent in their transcriptional responses. Changes in expression of these hormone-associated genes in the worker bee brain and HPGs may translate to proteins, and subsequently, to physiological outcomes such as behavioral alterations of foragers.


Karl Fenta, Tiffany Haltiner, Petra Kunz, Verena Christen; Insecticides cause transcriptional alterations of endocrine related genes in the brain of honey bee foragers; Chemosphere
Available online 6 July 2020, 127542 In Press, Journal Pre-proof; https://doi.org/10.1016/j.chemosphere.2020.127542

https://www.sciencedirect.com/science/article/pii/S0045653520317379
 

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A network analysis of how neonicotinoids have become embedded in New Zealand’s agricultural practices

7.1 Summary of research findings
The overall aim of this thesis was to understand how neonicotinoids have become embedded -and remain- in NZ’s agricultural practices. Subsequently, four research questions were identified and developed to reach this primary goal. The main findings of this research are presented below and are organised according to those research questions.
My first task was to identify and describe the major actors influencing neonicotinoid use in NZ. This began with an extensive review of publicly available documents which identified actors concerned with the use of neonicotinoids in NZ. The CSSF (Latour, 1999a) also help direct me towards those actors involved in the making and maintenance of agricultural practices. Once I had performed the initial interviews, I also used snowball sampling to try and encourage each participant to direct me towards individuals whom they thought would suitable for this research.
Some of the actors which this process identified were endemic insect pests whose abundance, and affinity to modified pastoral landscapes, have contributed to NZ’s reliance on agricultural chemicals like neonicotinoids and are used by other actors to convince one another of the importance of neonicotinoids. Next, there are landowners, they are the ones using seed treatment neonicotinoids on their properties to combat the vagaries of growing outdoors, meet the expectations of their consumers and maximise their yields. There are also beekeepers, who endure the adverse effects of neonicotinoids so that they can maintain relationships with landowners and secure access to valuable bee sites. Therefore, they are unlikely to complain if their hives are poisoned. Next, there are seed and chemical company representatives and product group representatives, these actors form strong relationships with international markets to secure market access for landowners, while simultaneously providing landowners with crop protection programmes, which include neonicotinoids, to ensure that a crop is produced. They also try and convince regulators not to ban neonicotinoids by demonstrating to them that neonicotinoids are vital for the production of key export crops. There are also international and domestic markets, which demand neonicotinoids are used in the production of hybrid seed crops and which self-regulate chemical residues on food. Lastly, there are the consumers, these actors demand that high yielding crops and food, which are free of pests, weeds, diseases and in some cases chemical residues, are available all year round.
My next task was to describe how certain relationships were formed and maintained between those actors. The interview questions attempted to draw out empirical evidence regarding
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neonicotinoids and encouraged the interview participants to discuss their relationships with the other actors listed above. This identified several relationships centred on the use of neonicotinoids in NZ’s agricultural practices. To illustrate, analyse and discuss these relationships, Latour’s CSSF (1999) was once again applied to the research. In summary, I found that neonicotinoids are embedded -and remain- in NZ’s arable sector because of a series of material relations between arable growers, NZ seed and chemical companies, international seed companies, beekeepers, the NZEPA and consumers.
Firstly, what I have called the “arable profession” (autonomization) is formed by a three-way relationship between international seed companies, NZ seed and chemical companies and arable growers. International seed companies who demand high yielding and 100% seed crops interest NZ seed and chemical companies with payment and continued contracts to grow hybrid seeds in NZ, in return the NZ seed and chemical companies guarantee the production of 100% and high yielding seed crops by offering NZ’s more relaxed rules when it comes to some substances deemed hazardous elsewhere (neonicotinoids). The NZ based seed and chemical companies subsequently mobilise crop protection programmes, payment and access to markets to influence the farming practices of NZ’s arable growers. To secure their position NZ arable growers then mobilise a commitment to follow those crop management plans and use programs such as Agworld to confirm they have performed crop treatments as directed. Another relationship exists between arable growers and beekeepers (alliance). Essentially landowners convince beekeepers of their agricultural practices (use of neonicotinoids) by mobilising formal contracts, access to stances of highly valued Manuka and a fee for pollination services. Beekeepers similarly pay for access to honey-producing flora to interest arable growers in this relationship. Subsequently, due to the growth of NZ’s honeybee population and the Manuka honey market, those beekeepers with access to Manuka are unlikely to complain even in cases where their hives have been poisoned, this is due to the risk it poses their income. Next is the relationship is between the NZEPA, arable product groups and arable growers (alliance). Once again, this relationship relies on the trade of resources; product groups collect levies from growers based on yield, land area or at a fixed rate and in return and growers receive marketing, research and development as well as some practical support in return. Arable product groups also provide lobbying of the NZEPA, convincing them that neonicotinoids are essential for the success of key export crops, by mobilising critical use cases. Subsequently, the NZEPA is convinced of neonicotinoids importance to NZ’s agricultural production and are also convinced that biodiversity declines are not caused by neonicotinoids. In return the NZEPA do not changed neonicotinoid regulations. Finally, there is a relationship between the users of NZ grown hybrid (consumers) seeds and international seed companies (public representation). The international consumers interest the international seed companies with payment and those companies provide the consumers with the seed.
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This demonstrates that each of the actors had a different role in the embedding and maintenance of neonicotinoids in NZ’s arable sector. Furthermore, the relationships between the actors are caused by their shared need to achieve their goals. Therefore, the actors are connected in a way that makes neonicotinoids indispensable for each of them to achieve their goals. It is in this regard that the actors make up the network, and their material relations serve to make and maintain neonicotinoids in NZ’s agricultural practices.
My third question was to explain why knowledge opposing the use of neonicotinoids has been unsuccessful in removing it from NZ’s agricultural practices. Like the above question, this was answered through the application of Latour’s CSSF (1999a) in Chapter 6, but its answer began during the data collection process. While performing the interviews, I found that the context surrounding an agricultural practice was present in the material relations I traced and therefore significantly impacted the application of neonicotinoids. Essentially, the embedding of an agricultural practice cannot simply be explained by the scientific resources supporting or opposing its use. To this end, I found that even the commodity being produced, and the agricultural sector was affecting practices. It became apparent very quickly that neonicotinoids were embedded in NZ’s arable sector but have been removed from NZ’s apples and pears sector. Through the application of Latour’s CSSF (1999a), I observed that a slight change in the “public representation” loop of the CSSF (Latour, 1999a, p. 103), circulated through all the other loops of the network and led to neonicotinoids being removed from the apples and pears sector’s pest control programmes. In summary, consumers of NZ’s apples and pears want to know what practices are contributing to the production of their food. Moreover, they want to make sure that chemicals which they are concerned about and are banned where they live (neonicotinoids) are not being used in the production of the food which they eat. Supermarkets who are directly connected to the consumer, through the transfer of resources, translate this demand into MRLs. Subsequently, to ensure MRLs are met and to maintain market access, apples and pears NZ have removed neonicotinoids from the crop protection plans, introducing an alternative and advising growers about changes in supermarket regulation and consumer demand. Apple and pear growers have therefore “tended to move away from them [neonicotinoids] and look for alternatives” (Product Group Representative 1). Thus, neonicotinoids have been removed from the agricultural practices of NZ’s apples and pears sector. This subsequently contradicts my initial assumption that neonicotinoids are embedded -and remain- in NZ’s agricultural practices.
Finally, I was charged with understanding how Latour’s CSSF (1999) could be used to investigate similar controversies in the future, in particular, those which involve hazardous substance use in NZ’s agriculture. To achieve this, in light of my research I critiqued and responded to critiques of Latour’s CSSF (1999a) and Callon’s key principles (1986). Firstly the principle “generalized symmetry” was vital for this research, by allowing me to highlight that MRLs are first shaped by international
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supermarkets and then shape the crop protection programs produced by apples and pears NZ and therefore fresh product growers ending neonicotinoid use. Similarly, it enabled me to demonstrate the importance of grass grub in helping shape the crop protection programmes of NZ seed and chemical companies and therefore arable growers’ use of neonicotinoids. Secondly, by presenting the conflicting viewpoints of all the actors and quoting the exact words of the interview respondents, limiting my biased commentary, I further addressed critiques of “generalized symmetry” as well of those of “agnosticism” (see section 3.5). Essentially through the use of a thematic analysis I have still identified power relations and social hierarchies as they have emerged from the data. Next I addressed critiques of the CSSF’s imposition of its “own theoretical lexicon” (Whittle and Spicer, 2008). Essentially the CSSF’s interpretation by no means matches the world of the interview participants. This is largely because the vocabulary being used is vastly different from that used by the interview participants. To address this, I provided a thorough description of the case and the participants and presented many quotations which give insight into my translation of the interview participants’ responses. I also made a conscious effort to avoid using vocabulary from Callon (1986) and Latour (1999a) in the interview questions, so to avoid imposing this same vocabulary on the participants. Most importantly, Chapter 6 offers some insight into the major limitations and boundaries of myself and the research. By reflecting on my own limitations and the limitations of the tools which I used, I hope that future hazardous substance researchers will do a better job. To fully answer this question, the next section comments on what this research has contributed to CSSF and agricultural practice literature.

https://researcharchive.lincoln.ac.nz/bitstream/handle/10182/12152/Scott_Masters.pdf?sequence=4
 

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Silicone Wristbands as Passive Samplers in Honey Bee Hives

Abstract: The recent decline of European honey bees (Apis mellifera) has prompted a surge in research into their chemical environment, including chemicals produced by bees, as well as chemicals produced by plants and derived from human activity that bees also interact with. This study sought to develop a novel approach to passively sampling honey bee hives using silicone wristbands. Wristbands placed in hives for 24 h captured various compounds, including long-chain hydrocarbons, fatty acids, fatty alcohols, sugars, and sterols with wide ranging octanol–water partition coefficients (Kow) that varied by up to 19 orders of magnitude. Most of the compounds identified from the wristbands are known to be produced by bees or plants. This study indicates that silicone wristbands provide a simple, affordable, and passive method for sampling the chemical environment of honey bees.

5. Conclusions
Considering the ease with which chemicals in bands can be compared, the minimal disturbance to the hive, and the variety of compounds detectable, using silicone bands to investigate the relationship between chemical compounds and honey bees shows great potential. Further, our results show that bands did not collect detectable compounds from outside of the hive, as no compounds were detected on the outside bands. This contrasts with SPME fibers, which are easily contaminated by background volatiles [16] and are quite expensive. Researchers can use bands as samplers in the open hive environment, as was done in this study, as well as in closed sampling containers. In a closed system, it would be possible to sample the volatile chemicals released by bees or adhered to the surface of bees based on certain castes, age groups, or environmental conditions, without the need for complicated air flow systems or filters. As a result, we believe using silicone band passive samplers provides alternative, flexible, more affordable opportunities to explore the chemical ecology of honey bees and the factors that influence their health, behavior, and survival.

Bullock, Emma & Schafsnitz, Alexis & Wang, Chloe & Broadrup, Robert & Macherone, Anthony & Mayack, Christopher & White, Helen. (2020). Silicone Wristbands as Passive Samplers in Honey Bee Hives. Veterinary Sciences. 7. 86. 10.3390/vetsci7030086.
https://www.researchgate.net/public...tbands_as_Passive_Samplers_in_Honey_Bee_Hives
 

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Nature and Nurture: Effects of Multi-Pesticide Exposure during Honey Bee (Apis mellifera) Development

Honey bees (Apis mellifera) are frequently used as pollinators in a variety of agricultural production systems. While collecting resources, honey bee foragers can fly for miles around a colony, unintentionally gathering pesticides and sequestering synthetic chemicals inside a hive. Additionally, beekeeper-applied chemicals are a dominant component of most within-hive chemical environments. A diversity of pesticides residues can therefore be retained within hive components such as beeswax and stored pollen. These matrices can ultimately pose an exposure risk to developing brood. We used previously reported in-hive pesticide residues to test how mixtures of frequently encountered pesticides can impact honey bee development:

1. We assessed the latent impacts of pesticides on adult queens by measuring how developmental exposure can impact a queen’s mating quality and the colony she later establishes,

2. We examined how colony-level pesticide exposure influences the nutritional quality of diet fed by nurse bees to developing queen larvae, and

3. We examined the differences in pesticide susceptibility and enzymatic detoxification across honey bee breeding stocks.

To investigate the effects of contact and oral multi-pesticide exposure during queen development, we reared queens in beeswax cups with or without an added multi-pesticide treatment and within colonies supplemented with treated (field-relevant pesticide mixture) or untreated pollen. We sacrificed queens post-mating to assess reproductive phenotype and established all remaining queens in standard hive equipment to measure colony growth. The colonies administered treated pollen produced fewer viable queens, and those queens which survived had significantly reduced stored sperm viability and tended to have a lower mating number. Furthermore, these queens later established colonies with lower brood viability. Our wax treatment contained a pesticide hazard-level similar to that of an average commercial colony and had no measureable effects. These findings indicate the downstream legacy effects of developmental exposure on queen mating quality and colony phenotype.

During development, honey bee queens are fed royal jelly (RJ) by nurse bees. We examined how pesticide exposure can influence the quality and quantity of RJ produced by a colony by exposing colonies to a multi-pesticide treatment in pollen and then harvested RJ from control and treated colonies. Thereafter, we measured the amount of RJ produced by colony, and screened samples for pesticide residues and nutritional composition.

Colonies exposed to treated pollen yielded a lower mean amount of RJ provisioned per queen, but this difference was not significant. RJ from treated colonies contained lower amounts of phytosterols as well as key proteins and lipids relative to RJ from control colonies. We report that RJ from treated colonies has similar pesticide residues relative to controls, indicating that nurse bees buffer developing larvae from direct oral exposure to pesticides. This suggests that the effects of colony-level pesticide exposure on queen quality manifest through nutritional perturbations in RJ composition.

Susceptibility is a key aspect of pesticide risk which we compared across seven breeding stocks by rearing larvae in vitro using diet spiked with a pesticide mixture at four doses. We then tested differences in the activity of the detoxification enzyme esterase and used proteomics by mass spectrometry to investigate differential protein expression.

We found that esterase activity towards two model substrates positively correlated with pesticide tolerance and the highly selected Pol-Line had larvae with the lowest pesticide tolerance and generally lower esterase activity. Conversely, larvae from progenitor and putatively feral stocks had the highest pesticide tolerance and esterase activity.

We found few differences in the larval proteome across stocks, which indicates that differences in pesticide tolerance may result from qualitative differences in detoxification enzyme structure. This finding highlights the potential for unintended consequences of artificial selection on pesticide tolerance in honey bees.


MILONE, JOSEPH PERRY. Nature and Nurture: Effects of Multi-Pesticide Exposure during Honey Bee (Apis mellifera) Development (Under the direction of Dr. David Tarpy).

https://repository.lib.ncsu.edu/bitstream/handle/1840.20/38086/etd.pdf?sequence=1
https://repository.lib.ncsu.edu/handle/1840.20/38086
 

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Dietary quercetin impacts the concentration of pesticides in honey bees

Highlights

• Honey bees orally exposed to imidacloprid exhibit reduced metabolism of quercetin.
• Dietary quercetin reduces the concentration of imidacloprid absorbed in honey bees.
• Dietary quercetin does not affect the concentration of tebuconazole or tau-fluvalinate in contact-exposed honey bees.

Abstract
Honey bees are important pollinators and are subject to numerous stressors, such as changing floral resources, parasites, and agrochemical exposure. Pesticide exposure has been linked to the decline in the global honey bee population. We have limited knowledge of the metabolic pathways and synergistic effects of xenobiotics in bees. Quercetin is one of the most abundant phytochemicals in plants and is therefore abundant in the honey bee diet. Quercetin can upregulate the detoxification system in honey bees; however, it is still unknown to what extent quercetin ingestion can reduce the content of absorbed pesticides. In this study, we investigated the effect of dietary quercetin on the contents of three pesticides in honey bees: imidacloprid (insecticide), tebuconazole (fungicide), and tau-fluvalinate (insecticide and acaricide). Bees were divided into two main groups and fed either quercetin-sucrose paste or only sucrose for 72 h. Thereafter, they were orally exposed to ∼10 ng/bee imidacloprid or contact-exposed to ∼0.9 μg/bee tau-fluvalinate or ∼5.2 μg/bee tebuconazole. After 1 h of oral exposure or 24 h of contact exposure, the bees were anaesthetised with CO2, sacrificed by freezing, and extracted with a validated QuEChERS method. Subsequently, the concentrations of the three pesticides and quercetin in the bees were determined with a triple quadrupole tandem mass spectrometer coupled to an HPLC system. No significant effect on the concentration of tebuconazole or tau-fluvalinate was observed in bees fed quercetin. Intake of quercetin led to a reduction in the concentration of imidacloprid in honey bees. Quercetin-rich plants may be exploited in future beekeeping.

Hamidreza Ardalani, Nanna Hjort Vidkjær, Bente B.Laursen et al., Dietary quercetin impacts the concentration of pesticides in honey bees, Chemosphere, Volume 262, January 2021, 127848, https://doi.org/10.1016/j.chemosphere.2020.127848

https://www.sciencedirect.com/science/article/pii/S0045653520320439

https://en.wikipedia.org/wiki/Quercetin
 

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Exposure to acetamiprid influences the development and survival ability of worker bees (Apis mellifera L.) from larvae to adults

Highlights
• The response of immune- and detoxification-related genes in honeybees to acetamiprid decreased with exposure time.
• Acetamiprid disturbed the development of honeybees from larvae to adults.
• Continuously exposure to acetamiprid at 25 mg/L reduced the lifespan of adult worker bees.

Abstract
In most cases, honey bees experience pesticide pollution in a long-term period through direct or indirect exposure, such as the development process from larvae to the pre-harvest stage. At present, little is known about how honey bees respond to pesticide stresses during the continuous development period. This study aims to examine effects of long-term acetamiprid exposure on the development and survival of honey bees, and further present the expression profile in larvae, 1-day-old, and 7-day-old adult worker bees that related to immune, detoxification, acetylcholinesterase (AChE) and memory. Honey bees from 2-day-old larvae to 14-day-old adults except the pupal stage were continuously fed with different acetamiprid solutions (0, 5, and 25 mg/L). We found that acetamiprid over 5 mg/L disturbed the development involving birth weight and emergence rate of newly emerged bees, and reduced the proportion of capped cells of larvae at 25 mg/L; gene expression related to immune and detoxification of worker bees exposed to acetamiprid was roughly activated, returned and then inhibited from larval to emerged and to the late adult stage, respectively. Moreover, lifespans of bees treated with acetamiprid at 25 mg/L were significantly reduced. The present study reflects the potential risk for honey bees continuously exposed to acetamiprid in the development stage.

Jingliang Shi, Ruonan Zhang, Yalin Pei, Chunhua Liao, Xiaobo Wu, Exposure to acetamiprid influences the development and survival ability of worker bees (Apis mellifera L.) from larvae to adults, Environmental Pollution, Available online 12 August 2020, 115345, https://doi.org/10.1016/j.envpol.2020.115345
https://www.sciencedirect.com/science/article/abs/pii/S0269749120360334
 

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Toxicology of commercial insecticide formulations for the bees Scaptotrigona aff. depilis and Apis mellifera L.

Résumé
Pesticides are believed to be responsible for the death of farmed and wild bees. Despite some studies on the active ingredients, little has been researched into the effects of commercial formulations, although there is evidence that inert materials potentiate the toxic effects of insecticides on bees. The present work aimed to assess the toxicity of three commercial products for bees
used in Brazil as a pesticide; Verismo® (Metaflumizon) and Actara® (Thiametoxam) in Apis mellifera and Evidence® (Imidacloprid) in Scaptotrigona aff. depilis should be examined comprehensively. The studies were carried out between 2016 and 2018 in the bee laboratory of the zootechnical department of the Federal University of Ceará and are based on the international protocols of the OECD (Organization for Economic Cooperation and Development).

Insecticide toxicity was assessed by different exposure routes using the topical average lethal dose (LD50) and the average lethal concentration per ingestion (LC50) for A. mellifera and the average lethal time (TL50), topically and orally for Scaptotrigona aff. depilis. Mortality data were recorded for Apis after 1, 6, 12, 24 and 48 hours and for 300 hours at intervals of 1, 6, 12 and 24 hours on the first day and every 24 hours from the second for Scaptotrigona due to insect exposure, with different Dosages of insecticides. For Apis the data were subjected to a log-logistic model or a Gompertz model with the help of the statistical environment R and for Scaptotrigona the data were subjected to a statistical analysis of the dose-response type using the Bioestat® program - version 5.3 . Actara® produced the DL50 topically 0.055 (24 h) and 0.052 (48 h) ng p.c./μL/abelha and the LC50 of uptake was 1.467 (24 h) and 0.095 (48 h) ng p.c./μL diet. Verismo® had a topical LD50 of 97.223 (24 h) and 1.157 (48 h) nL p.c./μL/abelha and the uptake LC50 was 2.493 (24 h) and 0.334 (48 h) nL p.c./μL diet. The topical TL50 Evidence® for Scaptotrigona aff. The depilis was 22.1 hours and 29.4 hours per intake.

The results showed that Actara is much more toxic than Verismo to A. mellifera regardless of the route of exposure. Evidence® is toxic to Scaptorigona aff. With depilis, however, the fatal effects of the product are more apparent when contamination occurs topically than when it is taken orally.

http://repositorio.ufc.br/bitstream/riufc/53300/3/2020_tese_lsgurgel.pdf
 

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Thiamethoxam exposure deregulates short ORF gene expression in the honey bee and compromises immune response to bacteria

Abstract
Maximizing crop yields relies on the use of agrochemicals to control insect pests. One of the most widely used classes of insecticides are neonicotinoids that interfere with signalling of the neurotransmitter acetylcholine, but these can also disrupt crop-pollination services provided by bees. Here, we analysed whether chronic low dose long-term exposure to the neonicotinoid thiamethoxam alters gene expression and alternative splicing in brains of Africanized honey bees, Apis mellifera, as adaptation to altered neuronal signalling. We find differentially regulated genes that show concentration-dependent responses to thiamethoxam, but no changes in alternative splicing.

Most differentially expressed genes have no annotated function but encode short Open Reading Frames (sORFs), a characteristic feature of anti-microbial peptides. As this suggested that immune responses may be compromised by thiamethoxam exposure, we tested the impact of thiamethoxam on bee immunity by injecting bacteria. We show that intrinsically sub-lethal thiamethoxam exposure makes bees more vulnerable to normally non-pathogenic bacteria. Our findings imply a synergistic mechanism for the observed bee population declines that concern agriculturists, conservation ecologists and the public.

Thiamethoxam exposure deregulates short ORF gene expression in the honey bee and compromises immune response to bacteria
Pâmela Decio, Pinar Ustaoglu, Kamila Derecka, Ian C. W. Hardy, Thaisa C. Roat, Osmar Malaspina, Nigel Mongan, Reinhard Stöger, Matthias Soller
bioRxiv 853291; doi: https://doi.org/10.1101/853291
https://www.biorxiv.org/content/10.1101/853291v3.full.pdf
 

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The effect of temperature on candidate gene expression in the brain of honey bee Apis

The effect of temperature on candidate gene expression in the brain of honey bee Apis mellifera (Hymenoptera: Apidae) workers exposed to neonicotinoid imidacloprid

Highlights
• Extremely low imidacloprid neonicotinoid insecticide concentration in combination with contrasting temperatures causes gene expression changes associated to several honey bee (Apis mellifera) physiological responses.
• Greatly gene expression changes in hsp70, hsp90 and nalcn were triggered by effect of the low concentration dose in comparison with the higher concentration used.
• Cold conditions accentuate the alteration of transcription of nalcn gene in honey bees exposed to low doses of neonicotinoid.

Abstract
Neonicotinoid insecticides are potent agonists of nicotinic acetylcholine receptors and are a major factor in the decline of pollinators worldwide. Several studies show that low doses of this neurotoxin influence honey bee physiology, however, little is known about how insecticides interact with other environmental variables. We studied the effects of two neonicotinoid Imidacloprid doses (IMD, 0, 2.5, and 10 ppb), and three temperatures (20, 28, and 36°C) on gene expression in the brains of worker honey bees (Apis mellifera). Using qRT-PCR we quantified the expression of eight key genes related to the nervous system, stress response, and motor and olfactory capacities. Gene expression tended to increase with the low IMD dose, which was further intensified in individuals maintained in the cold treatment (20°C). At 20°C the octopamine receptor gene (oa1) was underexpressed in bees that were not exposed to IMD, but overexpressed in individuals exposed to 2.5 ppb IMD. Also, heat shock proteins (hsp70 and hsp90) increased their expression at high temperatures (36°C), but not with IMD doses. These results suggest that despite the low insecticide concentrations used in this study (a field-realistic dose), changes in gene expression associated with honey bee physiological responses could be induced. This study contributes to the understanding of how neonicotinoid residual doses may alter honey bee physiology.


Catalina Manzi, Jonathan Vergara-Amado, Lida Marcela Franco, Andrea X.Silva, The effect of temperature on candidate gene expression in the brain of honey bee Apis mellifera (Hymenoptera: Apidae) workers exposed to neonicotinoid imidacloprid, Journal of Thermal Biology, Available online 15 August 2020, 102696, https://doi.org/10.1016/j.jtherbio.2020.102696
https://www.sciencedirect.com/science/article/abs/pii/S030645652030468X
 

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Effects of selected insecticidal substances on mRNA transcriptome in larvae of Apis m


Effects of selected insecticidal substances on mRNA transcriptome in larvae of Apis mellifera


Highlights
• Loss of honeybee colonies in last decades.
• Insecticides are dealt as possible drivers.
• We fed different insecticides to honeybee larvae.
• Transcriptional analyses via RT-qPCR.
• Differences concerning development, energy metabolism and immune system.

Abstract
For the last decade, scientists have reported a loss of honeybee colonies. Multiple factors like parasites, pathogens and pesticides are dealt as possible drivers of honeybee losses. In particular, insecticides are considered as a major factor of pollinator poisoning. We applied sublethal concentrations of four insecticidal substances to honeybee larval food and analyzed the effects on transcriptome. The aim was to identify candidate genes indicating early negative impacts after application of insecticidal substances. Honeybee larvae were kept in-vitro under hive conditions (34–35 °C) and fed with dimethoate, fenoxycarb, chlorantraniliprole and flupyradifurone in sublethal concentrations between day 3–6 after grafting. Larvae at day 4, 6 and 8 were sampled and their transcriptome analyzed. By use of a RT-qPCR array differences in gene expression of selected gene families (immune system, development detoxification) were measured. Targets mainly involved in development, energy metabolism and the immune system were significantly affected by the insecticidal substances tested, selectively inducing genes of the detoxification system, immune response and nutritional stress.

Arne Kablau, Jakob H.Eckert, Jens Pistorius, SoroushSharbati, Ralf Einspanier, Effects of selected insecticidal substances on mRNA transcriptome in larvae of Apis mellifera, Pesticide Biochemistry and Physiology
Available online 10 September 2020, DOI: https://doi.org/10.1016/j.pestbp.2020.104703
https://www.sciencedirect.com/science/article/abs/pii/S004835752030198X

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