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Geldrop, Netherlands

Weterings R.,Cat Drop Foundation | Weterings R.,Naresuan University | Umponstira C.,Naresuan University | Buckley H.L.,Lincoln University at Christchurch
Ecological Modelling | Year: 2015

Functional response models describe the relationship between predators and the rate at which prey are consumed. Traditional models are based on the density of prey and predators. More recently, the role of variables such as predator and prey size have received increased attention. This study presents several new modifications of existing functional response equations that incorporate predator size as a factor affecting capture rate and/or handling time. These models were tested on an experimental system in which we used several aquatic nepomorphan (Hemiptera: Heteroptera) predators of mosquito larvae. The models that best fitted our data were modified Beddington-DeAngelis and Hassell-Varley models in which predator size affected the handling time. Models in which predator size affected capture rates performed better than models without a predator size effect. This suggests that capture rates are also affected by predator size. This study shows that predator size is an important variable in functional response models, particularly when the size variation among predators is relatively large. © 2015 Elsevier B.V.

Weterings R.,Cat Drop Foundation | Weterings R.,Naresuan University | Umponstira C.,Naresuan University | Buckley H.L.,Lincoln University at Christchurch
Arachnology | Year: 2013

We investigated the predation rates of three common jumping spiders (Salticidae) on mosquitoes (Culicidae) in Southeast Asia. We released mosquitoes from the genus Armigeres in a terrarium together with single predatory spiders for a period of approximately 24 hours. Predation rates differed among spider species and among sexes: mean predation rates (± SE) for Plexippus petersi were 6.0 (=0.8) mosquitoes per day for male spiders and 9.2 (±0.85) for female spiders. Male spiders of the species Plexippus paykulli consumed 4.3 (±1.2) mosquitoes per day and female spiders fed on 10.8 (±1.6) mosquitoes per day. For Menemerus bivittatus the predation rates were 2.7 (±1.3) and 4.7 (±2.3) mosquitoes per day for male and female spiders respectively. For all species, female spiders fed on significantly more mosquitoes than male spiders. Mosquito density positively affected predation rates, but this effect was small. The observed predation rates are high relative to estimates for other mosquito predators, leading to the conclusion that salticids, particularly Plexippus spp, have the potential to be valuable biological control agents for mosquitoes.

Weterings R.,Cat Drop Foundation
Journal of Vector Ecology | Year: 2015

Tadpoles are often considered to be predators of mosquito larvae and are therefore beneficial for the control of certain disease vectors. Nevertheless, only a few species have actually been recorded to prey on mosquito larvae. The mosquito larvae predation rates of tadpoles of three common Thai anuran species (Bufo melanostictus, Kaloula pulchra and Hylarana raniceps) were experimentally tested. Tadpoles in varying developmental stages were used to assess a size/age effect on the predation rate. In addition, different instars of Culex quinquefasciatus were used in order to assess a prey size effect on the predation rates. All three species failed to show any evidence of mosquito larvae predation. Neither small nor large tadpoles fed on mosquito larvae. Prey size also did not affect predation. Although tadpoles do not feed on mosquito larvae, there may be other direct or indirect inter-specific interactions that adversely impact the development of larvae in shared habitats with tadpoles. © 2015 The Society for Vector Ecology.

Weterings R.,Cat Drop Foundation | Weterings R.,Naresuan University | Umponstira C.,Naresuan University | Buckley H.L.,Lincoln University at Christchurch
Basic and Applied Ecology | Year: 2014

Environmental disturbances such as deforestation, urbanization or pollution have been widely acknowledged to play a key role in the emergence of many infectious diseases, including mosquito-borne viruses. However, we have little understanding of how habitat isolation affects the communities containing disease vectors. Here, we test the effects of habitat type and isolation on the colonization rates, species richness and abundances of mosquitoes and their aquatic predators in water-filled containers in northwestern Thailand. For eight weeks water-filled containers were monitored in areas containing forest, urban and agricultural habitats and mixtures of these three. Mosquito larvae of the genera Aedes and Culex appeared to be differentially affected by the presence of the dominant predator; Toxorhynchites splendens (Culicidae). Therefore, a predation experiment was conducted to determine predator response to prey density and its relative effects on different mosquito prey populations. Colonization rates, species richness and abundances of mosquito predators were strongly related to forest habitat and to the distance from other aquatic habitats. Areas with more tree cover had higher predator species richness and abundance in containers. Containers that were close to surface water were more rapidly colonized than those further away. In all habitat types, including urban areas, when predators were present, the number of mosquito larvae was much lower. Containers in urban areas closer to water-bodies, or with more canopy cover, had higher predator colonization rates and species richness. T. splendens (Culicidae) preyed on the larvae of two mosquito genera at different rates, which appeared to be related to prey behaviour. This study shows that anthropogenic landscape modification has an important effect on the natural biological control of mosquitoes. Vector control programmes and urban planning should attempt to integrate ecological theory when developing strategies to reduce mosquito populations. This would result in management strategies that are beneficial for both public health and biodiversity. © 2014.

Weterings R.,Cat Drop Foundation | Weterings R.,Naresuan University | Umponstira C.,Naresuan University | Buckley H.L.,Lincoln University at Christchurch
Journal of Asia-Pacific Entomology | Year: 2015

In Thailand, several important diseases are transmitted by mosquitoes. Many vector control programs focus on the reduction of these medically important mosquitoes through the application of pesticides, bed-nets and the introduction of biological control agents. Odonates naiads are important, naturally occurring predators of vector mosquitoes. To estimate the predation rates of odonate species in Thailand, we conducted an experiment in which the predation rates were compared across a range of predator and prey densities. We used seven different predator species from different instars that represented the composition of naiads in our study area. Body sizes ranged between 2.6. mm and 15.9. mm. Two different prey species were used, larvae of the mosquito Armigeres moultoni Edwards, 1914 and Aedes aegypti L. 1762. Predation rates showed a positive non-linear relationship with prey densities and a negative non-linear relationship with predator densities. The mean ± SE predation rates per predator were 6.2 ± 0.8 individuals per 24. h for dragonfly naiads and 5.1 ± 0.7 for damselfly naiads. Predation rates were very low compared to previously recorded rates. However, unlike previous research, we did not focus on single species in a late stage of development but on multiple species in all stages that resembled the natural odonata community composition. © 2014 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.

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