Minor pollinator–prey conflict in the carnivorous plant, Drosera anglica

Abstract

We studied the physical and temporal isolation of two arthropod guilds interacting with Drosera anglica Huds., a terrestrial carnivorous plant. Flowers are separated from basal trap leaves by a leafless stalk. Since arthropods are potentially employed both as prey and pollinators, we asked whether separation of traps from flowers reduces the frequency with which flower visitors are captured by the leaves. Plants captured prey throughout the season, with peak trapping activity occurring before flowering began. The diverse prey spectrum included at least 109 species in 94 genera in 26 of 37 identified families representing 11 arthropod orders. The most common prey were adult flies of Nematocera, particularly Ceratopogonidae (50%) and Chironomidae (42%). The following taxa were periodically abundant: Acarina, Diptera -Cecidomyiidae, Chloropidae, Sciaridae, Hemiptera nymphs and Thysanoptera -Thripidae. Flies (Diptera) were chief flower visitors (95%), dominated by Syrphidae (66%), Bombyliidae and Muscidae (10% each), Calliphoridae (7%), Tachinidae and Dolichopodidae (3% each). Additionally, visitors were a bee (Hymenoptera -Halictidae) and thrips (Thysanoptera -Thripidae). Four families were common to both guilds: Diptera -Dolichopodidae, Muscidae, Tachinidae; and Thysanoptera -Thripidae. However, direct comparisons of identified taxa within these families showed that overlap between flower visitors and prey occurred for Thrips sp. larvae alone, which comprised only 3% of all flower visitors and 0.5% of prey. Drosera anglica exploits distinct guilds of insects for pollinators and prey.

Toward an Evolutionary Definition of Cheating

“…However, if they were just mimicking a cue of a food source, to attract in a range of insects, including nonpollinators, then they would not be exploiting a cooperative interaction, and so would not be cheats. Empirical data supports the latter (Ellison and Gotelli 2001;Murza et al 2006;Ellison and Gotelli 2009;Gibson and Waller 2009 kind of cooperation is being cheated, and how it is being cheated. Cooperators could respond to cheats in at least four ways.…”

Pollinator‐prey conflict in carnivorous plants

“…By contrast, Drosera flowers and adhesive leaf traps are active at the same time (see e.g. Murza et al , 2006; Sciligo, 2009) so a PPO might arise if not prevented by other mechanisms.…”

Revisão taxonômica do clado tetraploide-brasileiro de Drosera L. (Droseraceae).

“…Os estudos sobre polinização de Drosera restringem-se a poucas espécies do hemisfério Norte (Juniper et al, 1989;Wilson, 1995;Murza & Davis, 2003Murza et al, 2006) e África do Sul (Anderson, 2010). Em geral, esses estudos focam no conflito polinizador-presa, o qual consiste na hipótese de que as hastes florais longas foram selecionadas em espécies de plantas carnívoras por aumentarem a distância entre as flores e as armadilhas, reduzindo, assim, as chances de os polinizadores tornarem-se presas (Juniper et al, 1989 (Murza et al, 2006;Anderson, 2010).…”

“…Em geral, esses estudos focam no conflito polinizador-presa, o qual consiste na hipótese de que as hastes florais longas foram selecionadas em espécies de plantas carnívoras por aumentarem a distância entre as flores e as armadilhas, reduzindo, assim, as chances de os polinizadores tornarem-se presas (Juniper et al, 1989 (Murza et al, 2006;Anderson, 2010). Segundo os estudos acima citados, os principais visitantes de flores de Drosera são pequenas moscas-das-flores (Diptera:…”

“…Estudos com diferentes espécies de Drosera encontraram uma sobreposição muito baixa entre os insetos capturados e os visitantes florais, o que sugere que, ao menos neste gênero, tal conflito seria minimizado pela exploração de guildas diferentes de insetos como polinizadores e presas, como resultado de ofertas divergentes presentes em flores e em armadilhas (Murza et al, 2006;Anderson, 2010). Segregação ainda mais evidente é aquela observada em Utricularia, Genlisea e Aldrovanda, cujas armadilhas ficam enterradas no solo ou dentro d`água, enquanto as flores são aéreas -mesmo assim, hastes longas são comuns nos dois primeiros gêneros.…”