Vertical and seasonal distributions of flying beetles were investigated in a suburban temperate deciduous forest in Kanazawa, Japan using water pan traps to determine the abundance and composition among vertical strata, change in the abundance and composition through seasons and determinant factors in generating the distributions. Traps were placed at three levels (0.5 m, 10 m, and 20 m above ground) on a tower. Samplings were carried out seasonally from May to November in 1999 and 2000. Variations in the abundance of flying beetles were observed from different layers. The results showed that the abundance and composition of flying beetles varied among strata and seasons. In both 1999 and 2000, Elateridae was consistently most abundant in the bottom layer, while Attelabidae and Cantharidae were most abundant in the upper layer. In 1999, Eucnemidae and overall scavengers were most abundance in the bottom layer, but results were not consistent with those in 2000. In general, the abundance of herbivores reaches a peak in the early season (May/June) and decreases in the following months. Peaks of abundance in predators vary vertically. In the bottom layer a peak was observed in the early season (May/June), while in the upper layer this was observed in July. Scavengers had two peaks, in May/June and September. These patterns indicated that vertical distributions in the abundance of different feeding guilds varied through seasons.
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 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.
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