Sterile Insect Technique Programs Research Articles

Evaluation of Larval Diets for Mass Rearing of Aedes aegypti L. (Diptera: Culicidae)

The ability to mass-produce quality insects in the laboratory is vital in any sterile insect technique (SIT) program. In mass-rearing Aedes aegypti, optimizing larval diet and conditions is essential as they directly affect adult traits that are important in future sterile male releases. This study aimed to evaluate different mosquito diets and determine the effects of changing parameters in the diet on the growth and development of Ae. aegypti (Old Balara strain). Different diets, densities, diet concentrations and the addition of brewer’s yeast (BY) were evaluated in rearing mosquito larvae. The cat food (CF) diet showed a more synchronized day of pupation at five days, where 80% of males already pupated regardless of larval density. In all three diets, a larval density at 2 larvae/mL of water was comparable to 1 larva/mL, saving more space and reducing the water requirement of Ae. aegypti without affecting its quality. The addition of BY resulted in significantly reduced time to pupation, increased pupation and adult emergence percentages. Among the diet concentrations, 0.2 mg/larva was the ideal concentration for CF and International Atomic Energy Agency diets and 0.3 mg/larva for the commercial fish meal due to shorter larval durations, longer adult longevity and longer adult wing lengths. In rearing Ae. aegypti, it is best to use CF with BY at 0.2 mg/larva/day at 2 larvae/mL.

Dynamics of the Queensland Fruit Fly Microbiome through the Transition from Nature to an Established Laboratory Colony.

The transition from nature to laboratory or mass rearing can impose significant physiological and evolutionary impact on insects. The Queensland fruit fly (also known as ‘Qfly’), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is a serious economic pest that presents major challenges for horticulture industries in Australia. The sterile insect technique (SIT) is being developed to manage outbreaks in regions that remain free of Qfly and to suppress populations in regions where this species is endemic. The biology of Qfly is intimately connected to its microbiome. Therefore, changes in the microbiome that occur through domestication have implications for SIT. There are numerous studies of the microbiome in Qfly larvae and adults, but there is little information on how the microbiome changes as Qfly laboratory colonies are established. In this study, high-throughput Illumina sequencing was used to assess the Qfly microbiome in colonies reared from wild larvae, collected from fruit, for five generations, on a gel-based larval diet. Beta diversity analysis showed that the bacterial communities from Generation 5 (G5) clustered separately from earlier generations. At the genus level, bacterial communities were significantly different between the generations and mostly altered at G5. However, communities were found similar at phyla to family taxonomic levels. We observed high abundance of Morganella and Burkholderia at the genus level in the larval and pupal stages respectively at G5, but these were not detected in earlier generations. Overall, our findings demonstrate that the domestication process strongly affects the Qfly microbiome and prompts questions about the functional relationship between the Qfly and its microbiome, as well as implications for the performance of insects that have been domesticated and mass-reared for SIT programs.

The microbiome of wild and mass-reared new world screwworm, Cochliomyia hominivorax

Insect population control through continual releases of large numbers of sterile insects, called sterile insect technique (SIT), is only possible if one can mass-rear large quantities of healthy insects. Adaptation of insect stocks to rearing conditions and artificial feeding systems can have a multitude of negative effects such as inbreeding depression, reduced compatibility with wild strains, unintentional selection for traits that lower fitness after release, and an altered microbiome. Changes to insect microbiomes can have many effects on insects ranging from a reduction in sex pheromones or reduced fitness. Thus understanding these systems is important for mass rearing and the performance of the sterile insect control programs. In this study we explored the microbiome of the New World screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) an economically important parasite of warm-blooded animals. Samples from myiases in cows and wild adults were compared to and mass-reared flies used by the SIT program. Significant differences were observed between these treatments, with wild captured flies having a significantly more diverse microbial composition. Bacteria known to stimulate oviposition were found in both wild and mass-reared flies. Two bacteria of veterinary importance were abundant in wild flies, suggesting screwworm is a potential vector of these diseases. Overall, this study provides the screwworm eradication program a platform to continue exploring the effects associated bacteria have on screwworm fitness.

Gut fungal community and its probiotic effect on Bactrocera dorsalis.

The oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) is a destructive horticultural pest which causes considerable economic losses every year. A collection of microorganisms live within the B. dorsalis gut, and they are involved in its development, physiology, and behavior. However, knowledge regarding the composition and function of the gut mycobiota in B. dorsalis are still limited. Here, we comprehensively characterized the gut mycobiota in B. dorsalis across different developmental stages. High-throughput sequencing results showed a significant difference in fungal species abundance and diversity among different developmental stages of B. dorsalis. Quantitative polymerase chain reaction and culture-dependent methods showed that yeast species was the dominant group in the larval stage. We isolated 13 strains of yeast from the larval gut, and found that GF (germ-free) larvae mono-associated with strain Hanseniaspora uvarum developed faster than those mono-associated with other tested fungal strains. Supplementing the larval diet with H. uvarum fully rescued B. dorsalis development, shortened the larval developmental time, and increased adult wing lengths, as well as the body sizes and weights of both pupae and adults. Thus, our study highlights the close interactions between gut fungi, especially H. uvarum, and B. dorsalis. These findings can be applied to the sterile insect technique program to promote host development during mass insect rearing.

Temporal Viability of Aedes aegypti and Aedes albopictus Eggs Using Two Hygroscopic Substances as Preservatives under a Sterile Insect Technique (SIT) Program in Southern Mexico

Simple SummaryDiseases transmitted by Aedes mosquitoes, such as dengue, Zika, and chikungunya, are a public health problem of growing global concern. There are several strategies for mosquito control. One of them is the Sterile Insect Technique, which is a method of breeding millions of mosquitoes, where radiation is used in males to sterilize them. Then, the males are released into the wild. These sterile males mate with wild females without having offspring, thus decreasing field populations. However, one of the problems is being able to have a large number of viable eggs for these field operations. Therefore, this study evaluates the temporal viability of Aedes mosquito eggs employing two substances, such as hydrolyzed collagen and Hyalurosmooth®. These two moisturizing substances maintained viable Aedes. aegypti eggs for up to eight weeks.Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictus. Results showed that 85–95% of Ae. aegypti eggs were able to hatch up to week 8 after being treated with both hydrophilic compounds, compared with the control 66.3%. These two substances showed promising effects for keeping Ae. aegypti eggs viable during prolonged storage in mass rearing insect production focused on vector control SIT programs.

Methoprene treatment increases activity, starvation and desiccation risk of Queensland fruit fly

Juvenile hormone is an important regulator of sexual development in insects, and application of methoprene, a juvenile hormone analogue, together with access to a protein-rich diet, has been found to accelerate sexual maturation of several tephritid fruit fly species including Queensland fruit fly Bactrocera tryoni (‘Q-fly’). Such accelerated development is a potentially valuable means to increase participation of released males in sterile insect technique programs. However, there is a risk that benefits of accelerated maturation might be countered by increased vulnerability to starvation and desiccation. The present study investigates this possibility. After emergence, flies were treated with three levels of methoprene (0, 0.05%, and 0.5%) incorporated into a diet of sugar and yeast hydrolysate for two days after emergence. Survival of groups and individual flies was assessed under conditions of food stress, food and water stress, and ad libitum access to diet, and survival of individual flies was also assessed under desiccation stress. Most flies provided ad libitum access to diet were still alive at 7 days, whereas all stressed flies died within 4 days. Desiccation stressed flies had the shortest survival followed by food and water stress, and then food stress. Methoprene supplements increased susceptibility of flies to each stress. Flies subjected to food and water stress had the least lipid reserves at death, whereas flies subjected to desiccation stress retained the least water reserves. To investigate mechanisms that might underlie reduced survival under stress; we also quantified activity level of flies that were subjected to food and water stress and desiccation stress. Activity level was greater for flies provided methoprene, but did not vary with stress type or sex, suggesting that increased vulnerability of flies to stress is related to elevated metabolism associated with elevated activity. Deleterious effects of methoprene supplements on stress tolerance indicate a need for careful consideration of the conditions that will be encountered by flies in the field before deploying methoprene as a pre-release treatment in Q-fly sterile insect technique programs.

Extended pre‐release holding with raspberry ketone and methoprene as supplements: Field performance of Bactrocera tryoni males

AbstractIn Sterile Insect Technique (SIT) programs, the released sterile insects must attain sexual maturity at an early adult age so that a large proportion survive to mature and contribute to reducing reproduction of pest populations. Previous field studies based on release of adult Queensland fruit fly, Bactrocera tryoni (Froggatt) (‘Q‐fly’), at 2 days of age found a significant increase in the recapture of mature male Q‐flies when they were provided methoprene or raspberry ketone (RK) before release. SIT for Q‐flies has subsequently adopted release at 5 days of age; there is now a contextual need to re‐assess the merit of methoprene and RK supplements. We assessed field abundance and dispersal of mature sterile male Q‐flies that had been held for 5 days on pre‐release standard diets of sugar and yeast hydrolysate (3:1) (control) with and without methoprene or RK supplements. Overall, the proportion of control‐ and RK‐treated flies recaptured was higher than the proportion of methoprene‐treated flies recaptured. We found no evidence that either methoprene or RK supplements yielded improvements over the control diet alone concerning abundance and dispersal of the male Q‐flies. Laboratory studies indicate that while the doses of methoprene (control + methoprene at 0.05% or 0.5%) and RK (control + RK at 1.25% or 5%) used in field releases at 2 days of age did not affect male longevity when sustenance was provided, these doses resulted in reduced longevity when no sustenance was provided. Furthermore, all doses of methoprene and RK used in field releases at 5 days of age reduced male longevity regardless of sustenance. At 5 days of age, the flies are already in an advanced state of maturity when released and in this context, it appears that additional pre‐release treatments of methoprene and RK provide no further improvement and may even be detrimental when nutrition is scarce.

Mitochondrial superoxide dismutase overexpression and low oxygen conditioning hormesis improve the performance of irradiated sterile males

The Sterile Insect Technique (SIT) is a successful autocidal control method that uses ionizing radiation to sterilize insects. However, irradiation in normal atmospheric conditions can be damaging for males, because irradiation generates substantial biological oxidative stress that, combined with domestication and mass-rearing conditions, may reduce sterile male sexual competitiveness and quality. In this study, biological oxidative stress and antioxidant capacity were experimentally manipulated in Anastrepha suspensa using a combination of low-oxygen conditions and transgenic overexpression of mitochondrial superoxide dismutase (SOD2) to evaluate their role in the sexual behavior and quality of irradiated males. Our results showed that SOD2 overexpression enhances irradiated insect quality and improves male competitiveness in leks. However, the improvements in mating performance were modest, as normoxia-irradiated SOD2 males exhibited only a 22% improvement in mating success compared to normoxia-irradiated wild type males. Additionally, SOD2 overexpression did not synergistically improve the mating success of males irradiated in either hypoxia or severe hypoxia. Short-term hypoxic and severe-hypoxic conditioning hormesis, per se, increased antioxidant capacity and enhanced sexual competitiveness of irradiated males relative to non-irradiated males in leks. Our study provides valuable new information that antioxidant enzymes, particularly SOD2, have potential to improve the quality and lekking performance of sterile males used in SIT programs.

Toxics or Lures? Biological and Behavioral Effects of Plant Essential Oils on Tephritidae Fruit Flies.

The family Tephritidae (Diptera) includes species that are highly invasive and harmful to crops. Due to globalization, international trade, and human displacement, their spread is continuously increasing. Unfortunately, the control of tephritid flies is still closely linked to the use of synthetic insecticides, which are responsible for detrimental effects on the environment and human health. Recently, research is looking for alternative and more eco-friendly tools to be adopted in Integrated Pest Management (IPM) programs. In this regard, essential oils (EOs) and their main compounds represent a promising alternative to chemical insecticides. EOs are made up of phytoconstituents formed from the secondary metabolism of many plants and can act as attractants or toxics, depending on the dose. Because of this unique characteristic, EOs and their main constituents are promising tools that can be used both in Sterile Insect Technique (SIT) programs and in the “lure and kill” technique, exploiting the attractiveness of the product in the former case and its toxicity in the latter. In this article, current knowledge on the biological and behavioral effects of EOs and their main constituents on tephritid fruit flies is reviewed, mainly focusing on species belonging to the Anastrepha, Bactrocera, Ceratitis, and Zeugodacus genera. The mechanisms of action of EOs, their real-world applications, and challenges related to their use in IPM are critically discussed.

Life Table of Bactrocera zonata (Saunders) (Diptera: Tephritidae) for Sterile Insect Technique (SIT) in Mauritius

Fruit flies (Tephritidae) have been reported to be a serious pest worldwide. In Mauritius, the major fruit fly species of economic and quarantine importance in agricultural production are Bactrocera zonata (Saunders), Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel). In line with the government's policy for sustainable and organic agriculture under the challenge of climate change, the Sterile Insect Technique (SIT) is being investigated as an alternative to chemical control. For successful cost-effective SIT programme island-wide, the production of competitive and sterile individuals for release is a key requirement. The aim of this study was to investigate the life cycle parameters of B. zonata to evaluate the feasibility of optimum mass rearing of this species. It was observed that B. zonata has a pre-oviposition period of 8 days, an oviposition duration of 51 days, the number of eggs per female along the complete oviposition period was 705 eggs and the peak egg hatchability varied from 88.5 to 91.5 %. The study showed that egg collection could be started as from day 13. The findings demonstrated that 5 weeks of egg collection is optimal for a rearing facility of B. zonata and production cages should be discarded on day 41. It was found that B. zonata has a net reproductive rate of 300.04 females and a mean generation time of 28.73 days. Given a positive Ro and a short T, it can be concluded that mass rearing of B. zonata is economically viable. Within a short period a laboratory population of this species for mass rearing can be established.

Transport from production facility to release locations caused a decline in quality of sterile Queensland fruit fly received for SIT application

AbstractFruit flies are among the most destructive horticultural pests. For Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), the sterile insect technique (SIT) is the main control method used in southeastern Australia. SIT involves the mass rearing of Qfly, sterilisation of pupae by irradiation, transport to release centres, and release of sterile Qfly to disperse into the environment. Mating of sterile and wild flies results in no offspring; thus, the wild population rapidly decreases. Previously, research has mainly focused on improvements within the production facility. However, transport from production facility to release sites is also an essential component in all SIT programs. Here, we examined historical records from the Victorian SIT program between 2002 and 2013 in three seasons (spring, summer, and autumn). We compared quality control (QC) data of irradiated fly pupae at the mass‐rearing facility in New South Wales (limited transport) to those of pupae transported to a release centre in Victoria (extensive transport). After extensive transport, pupal weight (−0.3 mg, or −3%) and flight ability (an overall 26% decline) were lower across all seasons, but particularly in spring. Adult emergence was lower across all seasons (an overall 23% decline), but particularly in summer. All three QC parameters were more variable after extensive transport. We discuss potential causes of the observed decreased pupal quality and avenues of future research to mitigate transport losses.

Probiotic based-diet effect on the immune response and induced stress in irradiated mass reared Ceratitis capitata males (Diptera: Tephritidae) destined for the release in the sterile insect technique programs.

Ceratitis capitata (medfly) is one of the most devastating crop pests worldwide. The Sterile Insect Technique (SIT) is a control method that is based on the mass rearing of males, their sterilization, and release in the field. However, the effectiveness of the technique depends on the quality of the released males and their fitness. We previously isolated and selected a probiotic bacteria (Enterobacter sp.), from wild-caught medflies, according to criteria that improved biological quality traits of reared medfly males.We firstly evaluated the impact of the irradiation on the expression of different immune and stress genes in the medfly sterile males. Expression was measured at differents time points ranging from 0 to 168 h after irradiation to capture the response of genes with distinct temporal expression patterns. Then, we supplemented the larval diet with previously isolated Enterobacter sp.strain, live and autoclaved at various concentrations to see whether the probiotic treatments affect, through their protective role, the gene expression level, and quality traits. The irradiation had significant effect on the genes attacin, cecropin, PGPR-LC, hsp23, and hsp70 level expression. The expression of attacin and PGPR-LC was up-regulated while that of cecropin was down-regulated. Hsp genes showed decreased levels between 0 and 18 h to peak at 72 h. However, the supplementation of the probiotic strain, either live or autoclaved, was statistically significant only for attacingene. However, significant interaction time x probiotic was noticed for attacin, cecropin, hsp23 and hsp70. The probiotic treatments also improved the quality control parameters like pupal weight. From this work we can conclude that a consortium of parabiotics (autoclaved probiotics) treatment will be recommended in insectaries considering both the beneficial effects on mass reared insects and its general safety for insectary workers and for environment.

Effect of a low cost diet on the cotton leaf worm, Spodoptera littoralis nucleopolyhedrosis virus pathogenicity and sterile insect technique

BackgroundMass rearing cost of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is one of the critical methods for the successful utilization of Baculovirus pathogenicity and sterile insect technique (SIT). Effectiveness of both SIT and S. littoralis Nucleopolyhedrosis Virus (SpliNPV) was assessed in response to plant-based diet and substitution of agar with commercial sources of gelling components as feed.ResultsPupal and adult recoveries produced by castor bean leaves were significantly high, followed by the agar-based diet. Moreover, larval durations were significantly prolonged for (starch + gelatin)-based diet than the other dietary diets. Obviously, SpliNPV pathogenicity against the larvae reared on (starch + gelatin)-based diet was 2.5 and 2 times higher than those reared on castor leaves and agar-based diet, respectively. Contrary to expectation, the sterility doses of male moths produced by castor leaves and agar-based diet were relatively similar.ConclusionThe findings suggest that the lowest cost diets (starch + gelatin)-based diet could be used effectively for increasing the SpliNPV pathogenicity, while either castor leaves or agar-based diet could be considered as a promising choice for SIT program.

Hypoxia combined with chilling maintains the quality of irradiated Drosophila flies: a simulated shipment experiment

AbstractDrosophila suzukii is an invasive fruit pest in Europe and America. Females lay eggs into mature fruit that larvae consume causing important losses. Sterile insect technique (SIT) is under development to control this pest. The efficiency of this technique relies on insect quality. However, during the process from mass production to field release, several steps may compromise insect quality and therefore SIT success. Shipment of sterile insects after irradiation is a key step of SIT programmes. Generally, insects are shipped as pupae and conditions during transport need to be adapted to prevent emergence before field release, while guaranteeing insect quality. To do so, transport is usually performed under low temperature, hypoxia or a combination of both. However, the impact of multiple stressors such as irradiation followed by chilling combined with hypoxia is poorly described and has not been studied in D. suzukii. Therefore, the aim of this study was to simulate a shipment of D. suzukii pupae (irradiated or not) under different conditions (chilling combined or not with hypoxia) for various durations, and to assess consequences on emerged adults. Irradiation followed by hypoxia and/or chilling only weakly altered emergence. However, 48 h of hypoxia without chilling altered the flight ability of flies whether or not they were irradiated. Conversely, when hypoxia was combined with chilling, flight ability remained similar to that of untreated flies. The use of chilling in combination with hypoxia for 48 h could be implemented as a transportation method for SIT programme on D. suzukii.

A Monte Carlo study to investigate the feasibility to use the Moroccan panoramic irradiator in sterile insect technique programs.

Mediterranean fly pest (Ceratitis) is one of the most destructive pests of fruit species in Morocco. The sterile insect technique (SIT) is an environmentally friendly strategy that uses ionizing radiation to sterilize adult insects. Morocco has a panoramic gamma irradiator used to irradiate agri-food products. This irradiator is not dedicated to SIT programs due to its geometry that does not allow to obtain a dose uniformity ratio (DUR) recommended for such applications. This article presents a Monte Carlo study to investigate the feasibility of using the panoramic gamma irradiator at the National Institute for Agronomic Research (NIAR) of Tangier, Morocco, to setting up SIT methods and contributing to Ceratitis control programs. The Monte Carlo method was used to simulate the concrete bunker in which the panoramic gamma irradiator is installed. To obtain a recommended DUR required for SIT programs, two cells similar of the Gammacell-220 irradiator, which is mainly used in the SIT programs around the world, were simulated inside the concrete bunker. The simulation and calculations were performed using the MCNPX-2.7e Monte Carlo simulation code. It is demonstrated that at both investigated positions, the spatial distribution of dose rates in the two modeled irradiation cells, which were similar to a gammacell-220 irradiator cell, are uniform enough that the cells can be used for SIT programs. It is concluded that the panoramic irradiator at NIAR can be used to contribute to the control of Mediterranean fly pest and other insect pests in Morocco.

Selection for age at reproduction changes pre‐mating period and mating frequency in Zeugodacus cucurbitae: impacts on insect quality control

AbstractIn the mass‐rearing of insects for sterile insect technique (SIT), it is important to maintain the quality of mass‐reared males so that they can compete with wild males in mating with wild females. Mass‐reared insects sometimes have shorter pre‐mating periods and higher mating frequencies than their wild conspecifics. Indeed, this was the case for mass‐reared individuals of the melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), used in the SIT program to eradicate the melon fly on the Southwest Islands of Japan. Therefore, I hypothesized that divergent artificial selection for age at reproduction altered these traits in the melon fly as well. To examine the effects of eggs produced by younger parents on each generation, six artificially selected lines were established, for which eggs were collected from young (Y lines) and old (O lines) females. Then, the pre‐mating periods and mating frequencies in males and females of the selected lines were compared. The results show a decreased pre‐mating period and an increased mating frequency in younger lines compared to older lines, which was driven by males rather than females. These traits ensure efficient offspring production in mass‐rearing, and are likely advantageous to the success of SIT programs. The impact of artificially selecting for these traits, especially in males, on insect quality and the efficiency of SIT is discussed.

Sex separation ofAedesspp. mosquitoes for sterile insect technique application: a review

AbstractSeparation of the sexes is necessary for the application of the sterile insect technique (SIT) in mosquitoes due to the hematophagous habits and disease vector activity of the females. In this review we analyze the history, current status, and future perspectives for the development of genetic sexing strains (GSS) ofAedesmosquitoes (Diptera: Culicidae). Various genetic control methods for mosquitoes are reviewed, as are their need for sex‐separation methods. We focus on areas of opportunity where GSS developed with classical genetic methods can be used. Regulatory restrictions and social acceptance of various control methods are analyzed. We conclude that the development of GSS by classical methods represents the most viable option for separation of the sexes and the application of large‐scale SIT programs within an area‐wide integrated vector management (AW‐IVM) approach.

The Possible Role of Microorganisms in Mosquito Mass Rearing.

Simple SummaryOne of the most promising control methods against Aedes albopictus is the sterile insect technique, which consists of mass rearing the target species, separation of males from females, and male exposure to sterilizing ionizing radiation. Once released in the environment, the sterile males are expected to search for wild females to mate with. The quality of sterile males is a crucial aspect in SIT programs in order to optimize effectiveness and limit production costs. The integration of probiotic microorganisms in larval and adult mosquito diets could enhance the quality parameters of the released sterile males.In Europe, one of the most significant mosquitoes of public health importance is Aedes albopictus (Skuse), an allochthonous species of Asian origin. One of the most promising control methods against Aedes albopictus is the sterile insect technique (SIT), which consists of mass rearing the target species, separation of males from females, and male exposure to sterilizing ionizing radiation. Once released in the environment, the sterile males are expected to search for wild females to mate with. If mating occurs, no offspring is produced. The quality of sterile males is a crucial aspect in SIT programs in order to optimize effectiveness and limit production costs. The integration of probiotic microorganisms in larval and adult mosquito diets could enhance the quality parameters of the released sterile males. In this review, we attempt to give the most representative picture of the present knowledge on the relationships between gut microbiota of mosquitoes and the natural or artificial larval diet. Furthermore, the possible use of probiotic microorganisms for mosquito larvae rearing is explored. Based on the limited amount of data found in the literature, we hypothesize that a better understanding of the interaction between mosquitoes and their microbiota may bring significant improvements in mosquito mass rearing for SIT purposes.

Estimation of Population Size and Dispersal Pattern of Sterile Male Aedes aegypti Using Mark-Release-Recapture (MRR)

Aedes aegypti is currently emerging as a main vector of Dengue, Zika, and Chikungunya transmission. Chemical control was reported to be less effective due to the resistance of this mosquito to some types of insecticides. Therefore, another vector control is needed which is most appropriate to be used, i.e. the sterile insect technique (SIT). Information about optimum range dispersal sterile male Aedes aegypti for optimalization SIT program are needed. This study was designed to determine the dispersal pattern and population estimation of Aedes aegypti sterilized with gamma rays using mark-release-recapture (MRR) method. After the male Aedes aegypti (pupal stage) was irradiated with 70 Gy of gamma rays, the mosquitoes were then marked with Rhodamine-B and released into the study site. MRR experiments were carried out in Batan Indah residential area, and the Aedes aegypti were released in center of the site. Mosquitoes were recaptured at 28 points spread over the Batan Indah Residence for 2, 4, 6, and 8 days after release by using BG-Sentinel Traps. The result showed that the population of Aedes aegypti in the site was estimated to be 5.402 (1.347–14.636; CI 95 %) with the furthest spread distance was 119 meters from the release point. This study also showed that the MRR experiment can be used to estimate the population size and dispersal pattern of Aedes aegypti movement in a given locality. The result of present study provide better understanding for optimalization mosquito-borne disease prevention based on SIT programs.

Comparative response to post‐production process of two Anastrepha ludens strains: Application in the sterile insect technique

AbstractThe new desiccation‐resistant (DR) strain of Anastrepha ludens Loew differs in its life‐history traits from the non‐selected strain (NS). Given the innate resistance of DR flies to stressors, it is necessary to determine the packing and shipment conditions for their use in the sterile insect technique (SIT). First, we used pupae to evaluate the interaction of hypoxia period (12, 24 and 36 hr) and temperature (15.3 (±0.9), 19.5 (±1.0), 25.5 (±0.6) and 30.1 (±0.5) oC). Second, adults were exposed to densities of 1.0, 1.3 and 1.5 flies/cm2 and chilling periods of 0, 3 and 5 hr. We observed a negative relationship of emergence and flight ability with hypoxia period and temperature in both strains especially when flies were exposed to 36 hr of hypoxia and 30℃. Interestingly, knock‐down time decreased as male density increased, but when chilling time increased, recovery time also increased. Both chilling time and male density had negative effects on male weight. Chilling time reduced male survival when exposed to desiccation, while both chilling time and male density decreased male survival under starvation conditions. Negative effects on number of matings were observed only on the first day after chilling but not on the following days. We found that DR flies survive approximately twice as long as flies from the NS strain when exposed to starvation or desiccation stressors. We discuss our results on the basis of the potential use of DR flies in SIT programmes.