Publications by authors named "Hanano Yamada"

The key to success in the application of the sterile insect technique (SIT) relies on the ability of released, sterile males to outcompete their fertile wild male counterparts to mate with wild females. However, many insect species exhibit multiple-mating behavior, which can be a way for females to select paternity for their progeny. This study aims to recognize the consequences of potential double-matings during an SIT program and to detect any evidence of sperm selection favoring sperm from fertile mates.

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The implementation of the sterile insect technique against Aedes albopictus relies on many parameters, in particular on the success of the sterilization of males to be released into the target area in overflooding numbers to mate with wild females. Achieving consistent sterility levels requires efficient and standardized irradiation protocols. Here, we assessed the effects of exposure environment, density of pupae, irradiation dose, quantity of water and location in the canister on the induced sterility of male pupae.

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Article Synopsis
  • - The sterile insect technique involves releasing sterile male insects to mate with wild females, effectively reducing the population by inducing sterility in females and is being developed for Aedes mosquitoes.
  • - High ratios of sterile males to wild females can lead to decreased longevity and feeding success in female Aedes mosquitoes due to mating harassment and reduced blood uptake.
  • - A field trial in China showed an 80% reduction in female biting rates and a 40% decrease in female mosquito density, indicating this technique can also lower disease transmission by increasing female mortality and reducing contact with hosts.
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Background: The sterile insect technique (SIT) is a green and species-specific insect pest control technique that suppresses target populations by releasing factory-reared, radiosterilized males into the wild. Once released, it is important to be able to distinguish the released males from the wild males for monitoring purposes. Several methods to mark the sterile males exist.

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  • - The study focuses on developing a new method for safely transporting sterile male mosquitoes over long distances for pilot programs using the sterile insect technique (SIT).
  • - Different types of mosquito transport boxes were tested to evaluate how well the mosquitoes survived, flew, and sustained any physical damage during transit, aiming for high-quality delivery from the lab to field sites.
  • - The results showed that the new transport method allows for successful shipment of sterile males for up to four days, achieving over 90% survival after 48 hours and improving their escape ability by over 20% with a recovery period post-transport.
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Article Synopsis
  • Balancing process efficiency while ensuring high biological quality of sterile male insects is crucial for the success of the sterile insect technique (SIT) in controlling mosquito populations.
  • The production and release of sterile males are affected by several stress factors, including mass rearing, irradiation treatments, and handling procedures, which can impact their competitiveness after release.
  • Research into dose fractionation of irradiation, where the sterilizing dose is split into two lower doses, has shown improved male longevity and mating success, though the increased labor involved in applying this technique may not justify the benefits.
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The sterile insect technique (SIT) is based on the inundatory field release of a target pest following their reproductive sterilization via exposure to radiation. Until recently, gamma irradiation from isotopic sources has been the most widely used in SIT programs. As isotopic sources are becoming increasingly expensive, especially for small programs, and regulations surrounding their procurement and shipment increasingly strict, irradiation capacity is one of the limiting factors in smaller or newly developing SIT projects.

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Article Synopsis
  • The study examines how the developmental stage of mosquitoes influences their reaction to ionizing radiation, focusing on adult males and the challenge of effective irradiation without compromising quality.
  • It compares the effects of irradiating mosquitoes in nitrogen (N), in air after nitrogen treatment (PreN), and in air, revealing that higher doses of radiation lead to lower egg hatch rates, particularly in nitrogen environments.
  • The findings suggest that nitrogen treatments can enhance the longevity of irradiated males and are effective for immobilization, with PreN emerging as the most efficient method for achieving sterility with minimal impact on male quality and shorter immobilization times.
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Background: South Africa has set a mandate to eliminate local malaria transmission by 2023. In pursuit of this objective a Sterile Insect Technique programme targeting the main vector Anopheles arabiensis is currently under development. Significant progress has been made towards operationalizing the technology.

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  • The study focuses on enhancing the sterile insect technique (SIT) by standardizing the quality control flight test device (FTD) to ensure a reliable release of high-quality sterile male mosquitoes.
  • Key factors that affect mosquito escape rates were identified as tube color, the use of lures and fans, mosquito species, age, and density, while factors like test duration and fan speed were found to be less significant.
  • A new, more affordable version of the FTD (version 2.0) was developed and successfully tested, proving effective for evaluating mosquito flight ability for SIT and similar programs.
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Reproductive sterility is the basis of the sterile insect technique (SIT) and essential for its success in the field. Numerous factors that influence dose-response in insects have been identified. However, historically the radiation dose administered has been considered a constant.

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Article Synopsis
  • The sterile insect technique is a sustainable approach for mosquito control, involving the release of sterile males into the wild.
  • The study explored how different mantis and gecko species prey on various mosquito species while considering the impact of specific treatments like chilling, marking, and irradiation on predation rates.
  • Results indicated that predation was consistent across treatments, with minimal effect on predation risk unless mosquitoes were exposed to excessive irradiation; suggesting further standardized trials could enhance quality control for the method.
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Self-contained gamma irradiators have been extensively used to reproductively sterilize insects for the sterile insect technique (SIT). More recently, the use of X-ray generators has gained attention due to the reduced investment, logistic, regulatory and safety requirements involved in the procurement, transport and operation of these machines compared with gamma irradiators. In this study, we evaluated a commercially available, "off-the-shelf" X-ray blood irradiator and found it suitable for insect irradiation in the frame of the SIT.

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The Joint FAO/IAEA Centre (formerly called Division) of Nuclear Techniques in Food and Agriculture was established in 1964 and its accompanying laboratories in 1961. One of its subprograms deals with insect pest control, and has the mandate to develop and implement the sterile insect technique (SIT) for selected key insect pests, with the goal of reducing the use of insecticides, reducing animal and crop losses, protecting the environment, facilitating international trade in agricultural commodities and improving human health. Since its inception, the Insect Pest Control Laboratory (IPCL) (formerly named Entomology Unit) has been implementing research in relation to the development of the SIT package for insect pests of crops, livestock and human health.

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  • The study examines how water quality, specifically hardness and electrical conductivity, affects the life cycle of mosquitoes, focusing on their development and productivity in different water types.
  • It compares the responses of two species of mosquitoes to various water mixtures, including purified water and tap water with varying hardness and conductivity levels.
  • Results show that higher water hardness and conductivity lead to longer pupation times, reduced productivity, and larger female sizes in one species, indicating that water with hardness over 140 mg/l CaCO3 or conductivity above 368 µS/cm is not suitable for optimal mosquito rearing.
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Cold storage and heat exposure are crucial components of tephritid fruit fly mass-rearing programs, as they influence the development and fitness traits of produced flies. This work investigated the effects of cold storage on the pupal developmental parameters and quality of (Hendel) genetic sexing strain (GSS) adults. Furthermore, the impact of short-term thermal exposure on the fecundity of (GSS) that also underwent pupal cold storage was examined.

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Article Synopsis
  • * The new MRC produced over a million eggs with minimal loss and demonstrated good measures for tracking adult survival rates.
  • * Results indicate that the new MRC is effective for mass-rearing in SIT programs, although further adjustments are needed to reduce egg collection escape issues. *
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Background: Mosquitoes are the deadliest animals in the world. Their ability to carry and spread diseases to humans causes millions of deaths every year. Due to the lack of efficient vaccines, the control of mosquito-borne diseases primarily relies on the management of the vector.

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Combined incompatible and sterile insect technique (IIT-SIT) has been considered to be an effective and safe approach to control mosquito populations. Immobilization of male adults by chilling is a crucial process required for the packing, transportation and release of the mosquitoes during the implementation of IIT-SIT for mosquito control. In this study, effects of chilling on the Aedes albopictus males with triple Wolbachia infections (HC line), a powerful weapon to fight against the wild type Ae.

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The production of a large number of mosquitoes of high biological qualities and reliable sex sorting before release are key challenges when applying the sterile insect technique as part of an area-wide integrated pest management approach. There is a need to fully evaluate the production capacity of the equipment developed in order to plan and maintain a daily production level for large-scale operational release activities. This study aimed to evaluate the potential use of the FAO/IAEA larval rearing unit for Aedes aegypti and the subsequent female contamination rate after sex sorting with a Fay-Morlan glass separator.

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Article Synopsis
  • The Sterile Insect Technique uses radiation-induced sterile males to control pest populations, and effective irradiation protocols are necessary for high-quality sterile insects.
  • A study was conducted on Aedes aegypti, Ae. albopictus, and Anopheles arabiensis to evaluate their oxygen consumption in water and examine the effects of radiation in hypoxic versus normoxic conditions.
  • Results showed that all species quickly depleted dissolved oxygen in water, with An. arabiensis being the fastest, and that hypoxic conditions provided a protective effect during irradiation, notably more significant in An. arabiensis.
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Aedes aegypti and Aedes albopictus are competent vectors of arboviruses such as dengue and chikungunya viruses which co-exist in some areas, including La Réunion island, Indian Ocean. A type of reproductive interference called satyrization has been described in sympatric species where dominant species mating fails to produce hybrids and thus reduces the fitness and tends to control the spread of the other species. Here, we investigated satyrization in laboratory experiments to provide insights on the potential impact on Ae.

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Mosquito-borne diseases represent a major threat to humankind. Recently, the incidence of malaria has stopped decreasing while that of dengue is increasing exponentially. Alternative mosquito-control methods are urgently needed.

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Article Synopsis
  • The text discusses the need for new solutions in the fight against malaria, highlighting the sterile insect technique (SIT) as a promising approach for mosquito control.
  • It presents a modified flight test device designed to assess the flight ability, and thereby the quality, of male Anopheles arabiensis mosquitoes by using various stress factors like irradiation and chilling.
  • Results showed that flight ability effectively predicted male quality post-irradiation, with significant impacts on survival and mating success beginning at specific irradiation doses and weight, indicating the importance of these factors in the control measures.
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  • The sterile insect technique relies on producing large quantities of high-quality mosquito eggs for effective biological control, making production efficiency crucial.
  • Psocids of the genus Liposcelis, particularly Liposcelis bostrychophila, are identified as pests that feed on stored mosquito eggs in insectaries, where conditions are favorable for their survival.
  • The report explores the feeding habits of these scavengers and offers strategies to prevent infestations, ensuring the integrity of mosquito egg stockpiles.
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