Assessment of Compaction, Temperature, and Duration Factors for Packaging and Transporting of Sterile Male Aedes aegypti (Diptera: Culicidae) under Laboratory Conditions

Optimized conditions for the packaging and transportation of sterile males are crucial factors in successful SIT programs against mosquito vector-borne diseases. The factors influencing the quality of sterile males in packages during transportation need to be assessed to develop standard protocols. This study was aimed to investigate the impact of compaction, temperature, and duration factors during packaging and transportation on the quality of gamma-sterilized male Ae. aegypti. Aedes aegypti males were sterilized at a dose of 70 Gy, compacted into Falcon tubes with densities of 40, 80, and 120 males/2 mL; and then exposed to temperatures of 7, 14, 21, and 28 °C. Each temperature setup was held for a duration of 3, 6, 12, 24, and 48 h at a 60 rpm constant vibration to simulate transportation. The parameters of mortality, flight ability, induced sterility, and longevity were investigated. Results showed that increases in density, temperature, and duration significantly increased mortality and reduced flight ability and longevity, but none of the factors significantly affected induced sterility. With a mortality rate of less than 20%, an escaping rate of more than 70%, considerable longevity, and the most negligible effect on induced sterility (approximately 98%), a temperature of 7 °C and a compaction density of 80 males/2 mL were shown to be optimized conditions for short-term transportation (no more than 24 h) with the minimum adverse effects compared with other condition setups.

Investigation of Developmental Stage/Age, Gamma Irradiation Dose, and Temperature in Sterilization of Male Aedes aegypti (Diptera: Culicidae) in a Sterile Insect Technique Program

The sterilization process using gamma irradiation is a crucial component in a program using sterile insect technique (SIT) to control Aedes aegypti. Unfortunately, there is no efficient standard protocol for sterilizing mosquitoes that can produce a high level of sterility while maintaining mating ability and longevity. Therefore, we conducted a study of the critical factors necessary to develop such a standard protocol. In this study, male Ae. aegypti pupae, as well as adults aged 1 d and 3 d, were irradiated using a Gamma-cell 220 irradiator doses of 0, 20, 40, 60, 70, 80, and 100 Gray (Gy). In addition, male Ae. aegypti in the pupal and adult stage aged 1 d were irradiated at a dose of 70 Gy at various temperatures. Changes in emergence rates, longevity, sterility, and mating competitiveness were recorded for each combination of parameters. Results showed that an increase of irradiation dose leads to a rise of induced sterility at all developmental stages, while simultaneously reducing emergence rate, survival, and mating competitiveness. Higher temperatures resulted in increased levels of sterility, reduced longevity, and did not affect the ability to mate. This study found that an irradiation dose of 70 Gy at a temperature between 20.00 and 22.30°C administered in the pupal stage induced a high level of sterility (around 98%), while maintaining mating competitiveness and longevity.

Ovitrap surveillance of dengue vector mosquitoes in Bandung City, West Java Province, Indonesia

Larval surveillance is the central approach for monitoring dengue vector populations in Indonesia. However, traditional larval indices are ineffective for measuring mosquito population dynamics and predicting the dengue transmission risk. We conducted a 14-month ovitrap surveillance. Eggs and immature mosquitoes were collected on a weekly basis from an urban village of Bandung, namely Sekejati. Ovitrap-related indices, namely positive house index (PHI), ovitrap index (OI), and ovitrap density index (ODI), were generated and correlated with environmental variables, housing type (terraced or high-density housing), ovitrap placement location (indoor or outdoor; household or public place), and local dengue cases. Our results demonstrated that Aedes aegypti was significantly predominant compared with Aedes albopictus at each housing type and ovitrap placement location. Ovitrap placement locations and rainfall were the major factors contributing to variations in PHI, OI, and ODI, whereas the influences of housing type and temperature were subtle. Indoor site values were significantly positively correlated to outdoor sites’ values for both OI and ODI. OI and ODI values from households were best predicted with those from public places at 1- and 0-week lags, respectively. Weekly rainfall values at 4- and 3-week lags were the best predictors of OI and ODI for households and public places, respectively. Monthly mean PHI, OI, and ODI were significantly associated with local dengue cases. In conclusion, ovitrap may be an effective tool for monitoring the population dynamics of Aedes mosquitoes, predicting dengue outbreaks, and serving as an early indicator to initiate environmental clean-up. Ovitrap surveillance is easy for surveyors if they are tasked with a certain number of ovitraps at a designated area, unlike the existing larval surveillance methodology, which entails identifying potential breeding sites largely at the surveyors’ discretion. Ovitrap surveillance may reduce the influence of individual effort in larval surveillance that likely causes inconsistency in results.

The dengue virus, transmitted by Aedes vectors, has been continuously spreading in tropical and subtropical countries, causing illness and fatality. Given the lack of a cost-effective dengue vaccine, the vector control approach for reducing the Aedes population remains the key method for mitigating dengue transmission. For a successful vector control program, an effective vector surveillance system is crucial for precisely predicting the spatial and temporal risk of a dengue outbreak. The ovitrap system improves data collection efficiency, aiding long-term dengue vector monitoring activities. This study is one of the few long-term dengue vector surveillance programs in Indonesia and provides compelling evidence of the need to improve the existing conventional larval surveillance system. The results demonstrated that two dengue vector mosquitoes, A. aegypti and A. albopictus, were present in the study area, and A. aegypti was more prevalent than A. albopictus. We observed an interactive relationship between ovitrap placement and rainfall in the dynamics of ovitrap-related indices; understanding this relationship allows for timely initiation of vector control and intervention strategies. We conclude that the ovitrap surveillance system is a sensitive tool for monitoring the population dynamics of Aedes vectors, predicting dengue outbreaks, and potentially improving community-based conventional larval surveillance.

Propolis Can Improve Caudal Fin Regeneration in Zebrafish (Danio rerio) Induced by The Combined Administration of Alloxan and Glucose

Hyperglycemia, a primary symptom in diabetes mellitus, is associated with difficulties in wound healing and regeneration. This condition is due to the length of the inflammatory phase and free radicals. Furthermore, there is evidence that molecular pathogenesis is involved in impaired wound healing in diabetics. As an animal model, zebrafish have many shared orthologous genes with human that are involved in protein regulation of wound healing and regeneration. Little is known about natural drugs that may be used to treat complications of wound healing in diabetes. Propolis, however, is known to consist of various organic compounds such as phenols and flavonoids with antioxidant and anti-inflammatory activities. This research aims to study propolis' effect on caudal fin regeneration and relative expression of several genes belonging to Hedgehog, bone morphogenetic protein (BMP), and Wnt signaling hyperglycemic (HG) zebrafish. GC-MS analysis and antioxidant activity testing were performed on ethanolic extract of propolis (EEP). Caudal fin regeneration was analyzed using ImageJ; blood glucose levels were measured; and relative gene expression analysis of shha, igf2a, bmp2b, and col1a2 was performed by the real-time polymerase chain reaction method with the β-actin housekeeping gene. Impairment of caudal fin regeneration in zebrafish hyperglycemia was characterized by a low percentage of regeneration and decreased relative gene expression. EEP at 15 ppm could increase the percentage of caudal fin regeneration and the expression of shha, igf2a, bmp2b, and col1a2. Based on the results, it appears that phenols and flavonoids from the EEP can improve the caudal fin regeneration of HG zebrafish.

Larval development of nypa palm worm Namalycastis rhodochorde (Polychaeta: Nereididae)

Abstract. Junardi, Anggraeni T, Ridwan A, Yowono E. 2020. Larval development of nypa palm worm Namalycastis rhodochorde (Polychaeta: Nereididae). Nusantara Bioscience 12: 148-153. Namalycastis intensive culture is still facing problems in mass production due to limited information on reproduction, especially in fertilization and production of larvae. The present research was designated to find out optimum salinity for fertilization and the production of nypa palm worm larvae (Namalycastis rhodochorde). Gamete samples were collected using a capillary glass tube inserted into ventro-lateral part of a body segment of a mature worm. Artificial fertilization was done by mixing the sperms and oocytes in a fertilization dish containing sterilized seawater as the medium. The larval development was observed until the benthic phase larvae (3-setigers). Fertilization was performed in medium salinity of 7-21‰ and water temperature of 25-29°C. The cleavage and larva stage occurred respectively within 28.20 to 58.67 minutes and within 72 to 80 hours after fertilization. The fertilization and larval development of N. rhodochorde were highly influenced by the medium salinity and temperature.

Banana Flower-Insect Interaction: Alpha-Pinene as Potential Attractant for the Insect Vector of Banana Blood Disease

Volatile metabolites are produced by plants for self-defense and as communication mediators with the environment. Terpenes are volatiles emitted as odorant cues for herbivores and microorganisms. This study was aimed to investigate volatile metabolites produced by banana flowers that attract insect vectors of BBD. The volatile metabolites from banana flowers were extracted by headspace-solid phase microextraction (HS-SPME) and identified by gas chromatography–mass spectrometry (GC-MS). It was apparent that the concentrations of the metabolite alpha-pinene gradually increased from the first to the the third stage. Comparison of metabolites produced by symptomatic banana male flowers for BBD infection with non-symptomatic ones showed that the concentration of alpha-pinene was higher in symptomatic male flowers. In addition, preference for alpha-pinene was tested on three insect vector species (Rhodesiella bhutanensis, Drosophila sp., and Musca sp.), analyzed by M. Anova p<0.001, F(1.5) =12.539 and Duncan test. Results showed that the insect vectors were mostly attracted to 20 µl volume of alpha-pinene compared to the other volumes and that alpha-pinene functioned as an attractant to these insects. This research is important for the formulation of attractants for insect vectors of BBD to control transmission of banana blood disease.