Biological mosquito control is affected by alternative prey

Abstract

Background: Mosquitofish were introduced to several countries of the tropics and subtropics as biological agents for the control of mosquito larvae. Meanwhile, they became a threat to native communities and fish worldwide, similar to other invasive species through resource competition, overexploitation, or habitat alteration. We investigated prey selectivity patterns of Gambusia affinis (mosquitofish) preying on larvae of the two Indian major carps (Catla catla and Labeo rohita) in the presence of varied proportions of alternative prey (rotifers, cladocerans, chironomid and mosquito larvae) under laboratory conditions. Results: The patterns of prey selectivity in mosquitofish were influenced by the presence of alternative prey and their relative abundance in the environment. Carp larvae, when present in equal proportions, were randomly selected by mosquitofish, however, positively selected when present in higher proportions. In the presence of Hexarthra mira, Daphnia similoides or the mosquito larval instar-IV as an alternative prey, the mosquitofish preferred fish larvae regardless of prey proportions. In the medium where either mosquito larval instar-I or chironomid larvae were given as alternative prey, the mosquitofish either rejected or randomly selected the carp larvae. Given a multispecies prey combination, mosquitofish primarily selected the larvae of L. rohita and mosquito larval instar-I. We also found a prey switching ability of mosquitofish in relation to varying abundances of prey species in the environment. Conclusions: The present results suggest that mosquito immatures are not the preferred food of mosquitofish when fish larvae are present in their natural habitats. Since mosquitofish and carp larvae have overlapping natural habitats and prey preferences are the invasive mosquitofish may have a substantial impact on native communities of invertebrates and fish. This way, they are equally important for extensive fisheries and conservation management.

Stable isotope analyses reveal predation on amphibians by a globally invasive fish (Gambusia holbrooki)

“…Goodsell and Kats () found that even when mosquito larvae are present, G. holbrooki prey on amphibian larvae to the same extent as when mosquito larvae are absent. This suggests that G. holbrooki follow, to some extent, the optimal foraging model (Werner and Hall, ; Kumar et al , ) which predicts that predators choose prey that minimize the energy used in foraging and optimize energy intake. Combining a stable isotope study with an estimation of abundance of each prey item in ponds would help to address this question.…”

Protistan epibionts affect prey selectivity patterns and vulnerability to predation in a cyclopoid copepod

“…All experiments, including 5 replicates for each treatment, were conducted in 30 × 20 cm glass troughs containing 2 L autoclaved tap water. A series of short-term experiments was conducted to investigate the feeding rates of the mosquito fish following the protocol used by Kumar et al 57 . The initial density (Table 2 ) for each prey type and test duration was chosen based on preliminary feeding experiments such that at experimental termination a substantial number of prey remained unconsumed.…”

Nutritional Dimensions of Invasive Success

“…Complementary food switching in response to food scarcity has been observed in the zebra mussel (Dreissena polymorpha) that alternates between seston and detritus when access to phytoplankton is limited [91], as well as in Nile perch in Lake Victoria that switched from increasingly rare cichlids to aquatic invertebrates and other fish taxa [92]. Dramatic relaxation of food selectivity during periods of scarcity has also been observed in the rat (Rattus rattus) [12], macaque (Macaca fascicularis) [93,94], fox (Vulpes vulpes) [95], and mosquitofish (Gambusia affinis) [96].…”