Asymmetric reproductive interference between specialist and generalist predatory ladybirds

Abstract

Summary1. Closely related species often differ greatly in the quality and breadth of resources exploited, but the actual mechanisms causing these differences are poorly understood. Because in the laboratory specialized species often survive and perform as well or better on host species that are never utilized in nature, negative ecological interactions restricting host range must exist. Here, we focused on reproductive interference, which has been theoretically predicted to drive niche separation between closely related species with overlapping mating signals. 2. We examined the interspecific sexual interactions in relation to ecological specialization and generalization in two sibling ladybird species, Harmonia yedoensis and Harmonia axyridis. Harmonia yedoensis is a specialist predator that preys only on pine aphids, which are highly elusive prey for ladybird hatchlings, whereas H. axyridis is a generalist predator with a broad prey and habitat range. 3. We experimentally showed that conspecific sperm fertilized the vast majority of eggs regardless of mating order (i.e. conspecific sperm precedence) when a female of H. yedoensis or H. axyridis mated with both a conspecific and a heterospecific male. Moreover, we demonstrated that mating opportunities of H. yedoensis females strongly decreased as heterospecific density increased relative to conspecific density. In contrast, in H. axyridis, female mating success was high regardless of conspecific or heterospecific density. 4. Our results suggest that the generalist H. axyridis should be dominant to the specialist H. yedoensis in terms of reproductive interference. Our results support the hypothesis that asymmetric reproductive interference from the dominant species may force the non-dominant species to become a specialist predator that exclusively utilizes less preferred prey in nature.

Island biogeography as a test of reproductive interference

“…Theoretical studies (Ribeiro and Spielman 1986;Kuno 1992) have opened our eyes to the ecological importance of reproductive interference. Recent empirical studies Takakura et al 2009;Crowder et al 2010;Takakura and Fujii 2010;Noriyuki et al 2012) have convinced us that reproductive interference exists broadly in many taxa at the individual level. The next advance in this theme requires more empirical studies conducted in the field at population level.…”

“…These predictive works have encouraged empirical studies. Now we have many examples of reproductive interference for a broad range of taxa: insects Kishi et al 2009;Noriyuki et al 2012), mites (Fujimoto et al 1996;Takafuji et al 1997), amphibians (Hettyey and Fig. 6 Results of nonmetric multidimensional scaling (NMDS) analysis of ISSR data from nine populations of V. p. lilacina.…”

“…Another reason is that the reproductive interference usually acts between closely related species. In many cases where reproductive interference has been empirically tested, the interacting species has been congeneric and belongs to the same trophic level (animals- Gröning et al 2007;Kishi et al 2009;Noriyuki et al 2012;plantsBrown and Mitchell 2001;Takakura et al 2009;Takakura and Fujii 2010). These tendencies and results of some empirical demonstrations of reproductive interference strongly suggest that it is a necessary mechanism that has driven the native species to extinction in interaction with closely related alien species.…”

Host specialization by reproductive interference between closely related herbivorous insects

“…When mating takes place on or near the host plant, the plant serves not only as food for the offspring but also as a mating site (e.g., Feder et al 1994). Therefore, reproductive interference may drive host partitioning among closely related species, creating spatial segregation of mating sites (Colwell 1986;Kuno 1992;Noriyuki et al 2012;Friberg et al 2013;Kishi and Tsubaki 2014;Noriyuki 2015). However, whereas some empirical studies have suggested the causal role of reproductive interference in the evolution and/or maintenance of host-plant partitioning as well as microhabitat partitioning, there is a need for modeling studies to address whether reproductive interference can indeed drive the evolution of host-plant partitioning.…”

Two-Way but Asymmetrical Reproductive Interference between an Invasive <i>Veronica</i> Species and a Native Congener

“…However, enormous numbers of alien species are known to create severe problems worldwide. Increasingly results of numerous empirical studies have also suggested that reproductive interference is biased or rather one-way [8,9,[14][15][16][17]. The extent of the bias of the reproductive interference between the alien and native species might provide a key to explaining the invasion speed of alien species.…”