Mosquitoes and other aquatic insects in fallow field biotopes and rice paddy fields

Abstract

Fallow field biotopes that develop from abandoned rice fields are man-made wetlands that provide new habitats for various aquatic animals. Although consideration of such biotopes generally focuses on their positive aspects, this study evaluated the negative aspects of establishing fallow field biotopes with regard to mosquito breeding sites. To determine whether fallow field biotopes become breeding habitats for vector mosquitoes, we evaluated mosquito fauna in fallow field biotopes and adjacent rice fields. We found larvae of Anopheles lesteri, Anopheles sinensis and Culex tritaeniorhynchus (all: Diptera: Culicidae) in the biotopes. Although abundances of mosquito larvae in the biotopes and rice fields were statistically similar, mosquito abundances in rice fields increased dramatically in August when the water level reduced after the rainy season. The abundance and variety of the mosquitoes' natural predators were greater in biotopes than in rice fields because the former are a permanent and stable aquatic environment. A generalized linear mixed model showed a negative effect of predator diversity on mosquito larvae abundance in both habitats. Although fallow field biotopes become breeding habitats for vector mosquitoes, establishing biotopes from fallow fields in order to protect various aquatic animals, including mosquito insect predators, may help to control mosquito breeding.

Observations on the pupal productivity of Culex tritaeniorhynchus in rice fields of West Bengal, India: implications for vector management (Diptera: Culicidae)

“…Under such scenario, the associated trap ponds in the landscapes play a crucial role acting as a source for the propagules. In dry conditions, dispersal of the predator and prey species between the rice fields and associated trap ponds and canals has been observed in many instances (Watanabe et al 2013;Ohba 2013Ohba , 2015. The habitat heterogeneity and the prey and predator refuge provided by the trap ponds and canals are considerably higher since no de-weeding activity is undertaken alike the rice fields proper.…”

“…As revealed through the relative density of the mosquito immature in the different weeks the stability in the relative abundance is lacking. This has been observed in rice fields in Japan and Kenya though the practice of paddy cultivation differs tremendously in these areas (Wada et al 1967;Chandlar & Highton 1975;Muturi et al 2008;Ohba et al 2013Ohba et al , 2015.…”

“…Empirical observations on the rice field mosquitoes in India and countries where paddy rice cultivation is a normal practice, the abundance of Anopheline and Culicine mosquitoes are guided by the environmental factors and the habitat permanence of the cultivable lands (Kant et al 1992(Kant et al , 1998Sunish & Reuben 2002;Banerjee & Chandra 2004;Keiser & al. 2005;Sunish et al 2006;Ohba et al 2013Ohba et al , 2015Lytra & Emmanouel 2014) cial determinant for the future abundance and dominance. Earlier studies have noted that the colonization of different species of mosquitoes occurs in sequence and the dominance pattern changes as a function of time (Chandlar & Highton 1975;Bang & Pant 1984;Begum et al 1986).…”

“…Entomological surveillance is a pre-requisite for estimating the variations in the mosquito immatures in the rice fields and allied habitats (Chase and Knight 2003;Derraik 2004;Keiser et al 2005;Dale & Knight 2008;Hassan et al 2010;Li et al 2011;Ohba et al 2013Ohba et al , 2015Amarasinghe and Weerakkodi 2014;Amarasinghe & Dalpadado 2014;Lytra & Emmanouel 2014). Random sampling of the selected sites in the rice fields are carried out to infer about the relative abundance of different mosquito species in space and time Ohba et al 2013Ohba et al , 2015Lytra & Emmanouel 2014).…”

“…Random sampling of the selected sites in the rice fields are carried out to infer about the relative abundance of different mosquito species in space and time Ohba et al 2013Ohba et al , 2015Lytra & Emmanouel 2014). Rice fields are heterogeneous habitats with changing community composition with time coinciding with the cultivation period and the harvest periods (Kant et al 1992;Sunish et al 2006;Yasuoka & Levins 2007;Muturi et al 2008;Watanabe et al 2013;Ohba et al 2013Ohba et al , 2015Lytra & Emmanouel 2014). During the wet conditions, the rice fields and allied habitats provide congenial conditions for the breeding of different species of vector and pest mosquito species Sunish et al 2006;Yasuoka & Levins 2007).…”