Aphids and their predators on marsh elder – June 23, 2014

Marsh elder aphids support one of the more diverse and easily observable salt marsh insect communities. Aphids on the marsh have no protection against predators or parasitoids. They are absolutely vulnerable. The only counter-measure available to them is high reproductive rate (by giving live births!) and overpowering by sheer numbers.

Female aphids giving birth to little nymphs

 One of the most conspicuous predators are the ladybugs, larvae and adults. They are strikingly beautiful animals. When it catches an aphid, the ladybug larva tears it apart with the powerful mandibles or jaws.

There are also some unusual creatures feeding on aphids. This is a flower fly larva (family Syrphidae). The larva looks like a greenish maggot. It actively searches for the aphid prey and when captured with a dart like mandibles, the larva sucks them dry. 

Aphids are practically sitting ducks for parasitoids, mostly tiny braconid wasps.  11 out of 33 or about 30% of the aphids on this leaf are mummies containing braconid wasp larvae. Aphid mummies look like dark inflated globules as opposed to the more normal reddish egg shape.

The taste of brine and phloem: The feast for herbivores (June 16, 2014)

Salt marsh elder, Iva frutescens, is the most common broadleaf bush in the salt marshes. This plant tolerates salinity but not frequent flooding, and is thus found at the upper edges of the marsh or along mosquito ditches. As the only “real” non-grassy plant and a relatively succulent one at that, Iva is attended by a variety of herbivores and their predators unmatched anywhere else on the salt marsh. Early in the season before predators and parasitoids catch up with them, plant eaters = herbivores have the upper hand. 

Damage by the end of the season in August

Aphids are the most obvious due to the sheer numbers. Brown ambrosia aphid (Uroleucon ambrosiae) can reach astonishing numbers very quickly. The population doubles in less than 3 days under optimal conditions. Like other aphid species, most reproduction occurs without males, i.e. through parthenogenesis. Live offsprings or nymphs are born every day.

When conditions on the plant become too crowded winged aphids are produced that can disperse to new habitat.

Another common herbivorous sojourner is the chrysomelid leaf beetle, Ophraella notulata. Unlike the brown ambrosia aphid, this little beetle is Iva specialist rarely found on other plants. The larvae look very fuzzy and are often seen in the company of aphids.

Paroxya grasshoppers also consume Iva leaves and are hard to detect. They prefer to hide by hunkering down rather than jumping. The grasshopper coloration and small size allow almost perfect blending in among Iva branchlets.  

Research by Steven Pennings group (http://www.esajournals.org/doi/abs/10.1890/10-0760.1) determined that predators and competition (i.e. “top down”) exercise much more influence on the aphids and the beetles than the plant resource (i.e. “bottom up”).

Unidentified leaf beetle (Chrysomelidae)

As usual, the marsh is full of flies, little and large. Many fly larvae feed on detritus abound in the salt marshes (which is in fact, dominated by detritivores), or are predacious on other insects. This curious fly (Taeniaptera trivittata) belongs to the stilt-legged fly family and behaves very convincingly like an ant. I’ve seen this fly species on the marsh. Is it possible that the larvae can survive in the saline environment? Not much known about the adult habits, but this is a very cool fly to watch.

Yet unidentified crane fly, a common sight early in the season. Who are you, fly?

The first week of June (02/06)

The salt mash has not gotten in the full spring mode yet. It’s been a long and (relatively) harsh winter. The marsh is a checkerboard of fresh spring greens and drab winter browns and grays. The little annual glasswart or Salicornia plant is struggling though the last year stubble. 

 Despite its small size, Salicornia is a cool plant: it is called halophyte because this glasswart grows in high salt environments. The plant is not only edible, but highly nutritious containing up to 33% salicornia oil, which is similar to safflower oil. People used to eat it in the past. Nowadays, Salicornia is grown in deserts and wastelands where freshwater is scarce but salt or brackish water is abundant, for high quality animal feed and also biofuel.

At the first glance, nothing is in common between Salicornia glasswart and the shore fly. But there is more to it that meets the eye. Shore flies (Ephydra spp.) are also halophytes well adapted to saline environments, and are among the most common insects on the salt marshes. 

The larvae of one species, Ephydra riparia, inhabiting the Great Salt Lake in Utah were consumed as food by local Native Americans. Since shore flies are so adapted to live in marginal habitats (one species thrives in pure petroleum pools), there is a tremendous potential to utilize these species for human consumption – enthomophagy, or as protein rich animal food, similarly to the lowly glasswart.