Feeding and parasitism of adultStenoperlaspp. (Plecoptera: Eustheniidae) in New Zealand

Abstract

The adult diets of two species of stonefly, Stenoperla prasina (Newman, 1845) and Stenoperla maclellani Zwick, 1979 were investigated by gut content analysis. Adults were collected throughout New Zealand by light-trapping at 77 streamside sites most of which were located in native forest. S. prasina was widely distributed and collected at 43 sites, whereas S. maclellani was sampled at 10 sites in the South Island only. Of 200 S. prasina and 42 S. maclellani dissected, 36% and 69% respectively, contained food. Microscopic examination of a subset of individuals indicated that the gut contents of both species were dominated by sooty mould fungi with lesser contributions made by plant tissue, pollen grains and the spores of tree ferns. These findings suggest that stoneflies had been feeding on the trunks, branches and foliage of trees and perhaps on fronds of tree ferns. As the abdomens of most females were packed with eggs, which mature in late-instar nymphs it is likely that feeding provides adults with a source of immediately available energy for mating and flight. Encysted larval stages of hairworms (Nematomorpha) and a trematode were also found in both stonefly species. Metacercarial cysts of the trematode are the first records of larval flukes parasitising New Zealand stoneflies. They were found in about 43% of dissected adults of each species with up to 40 cysts present in some individuals. It is possible that the parasite's definitive host is one of New Zealand's native bats (Chiroptera), which are known to eat Stenoperla and inhabit streamside forests at some of the localities where parasitised stoneflies were taken. Overall, our results provide further evidence for the importance of sooty mould fungi as a food source for New Zealand insects and highlight the role of Stenoperla as a vector of larval parasites from aquatic to terrestrial hosts.

Intra- and interspecific genetic diversity of New Zealand hairworms (Nematomorpha)

“…While no intermediate hosts of New Zealand hairworms have been experimentally confirmed, Winterbourn (2005) found that adult stoneflies of the species Spaniocerca zelandica and Cristaperla fimbria exhibit a high prevalence of infection (69-90%) by nematomorph larvae. Winterbourn and Pohe (2016) subsequently found nematomorph larvae in two species of another New Zealand stonefly genus, Stenoperla. Previous studies of stonefly dispersal have demonstrated that adult stoneflies can travel hundreds or even thousands of metres along and between stream corridors (Briers et al 2004;MacNeale et al 2005).…”

Trophic ecology of Plecoptera (Insecta): a review

“…Hynes 1942;Brinck 1949;Harper & Hynes 1972). Among other studies in captivity, that of Collier and Scarsbrook (2000) is highly significant, since they reported that when Zelandoperla decorata is fed sugar solution and fungi, the females develop eggs, and both males and females gain weight (in Winterbourn & Pohe 2017). Smith and Collier (2000), in their study on Gripopterygidae, found some incongruences between results obtained by means of gut content analyses and those from stable isotope analyses (coming from both the animals and the potential food resources), indicating that a combined investigation of the diet and the movements during the adult life is needed to resolve these issues.…”

“…This also occurs in some Antarctoperlaria. For instance, Stenoperla species (Eustheniidae) from New Zealand mature a large quantity of eggs during their last nymphal stage, but they actively feed when adults (Winterbourn & Pohe 2017). Obviously, this does not mean that adult feeding in most stoneflies does not play an important role in the adult stage for egg maturation and/or other biological aspects, as demonstrated by some authors (e.g.…”

“…Obviously, this does not mean that adult feeding in most stoneflies does not play an important role in the adult stage for egg maturation and/or other biological aspects, as demonstrated by some authors (e.g. Hynes 1942Hynes , 1974Brinck 1949;Benedetto 1970;Rupprecht 1990;Zwick 1990;Winterbourn & Pohe 2017), a topic that will be addressed more in depth below.…”

“…It must be noted that Stenoperla is currently considered an endemic genus of New Zealand, while the former Australian Stenoperla australis Tillyard, 1921 was transferred to a different genus (Cosmioperla) (McLellan 1996). In fact, Winterbourn and Pohe (2017) showed, from gut content analyses, that Stenoperla prasina (Newman, 1845) and Stenoperla maclellani Zwick, 1979 (Eustheniidae) from New Zealand feed mainly on sooty mould fungi and, to a lesser extent, on plant tissue, pollen and the tree fern spores that they probably obtain by feeding on the trees. These authors pointed out that, as mature nymphs of these Stenoperla species have a great quantity of developed eggs, adult feeding provides energy mainly for mating and flight.…”