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. 

Salt marsh waking up in May

Finally, the temperatures are in the balmy 80s. Whereas last week the marsh looked brown and dead, with few signs of 6- or 8- legged life besides the ubiquitous Pardosa littoralis, the thin legged wolf spider, this week was very different. Planthoppers and flies happily cavorted around in the grass or on the mud flats. Water boatmen and mosquito larvae frolicked in the little pools. A rare guest visited from the woods nearby. 

Hister beetles (Histeridae) love decaying matter- carrion, dung, and rotting plants. They are not scavengers but predators searching for a snack of maggots or other arthropods found in those habitats. Perhaps this beetle was attracted by a dead animal; it also got a little hitchhiker or maybe a transitory companion, a tiny red mite running up and down the much larger beetle.

The thin legged wolf spiders (Pardosa littoralis) were as numerous as ever scattering in all directions. These spiders are semi-aquatic and run on water as if it were dry land. They can reach densities of up to several hundred per square meter, and are voracious predators of planthoppers and other invertebrates. This spider is a particularly good candidate for an indicator species of healthy salt marsh environment. 

While the spiders may snatch a mosquito larva out of the water, the salt marsh mosquitoes have evolved to avoid predation by unpredictable and irregular emergence, and to overcome any generalist predators by sheer numbers. The “balling” behavior is typical of the late instar or stages of the eastern salt marsh mosquito, Aedes sollicitans. Hundreds or thousands of larvae pack closely together to form tight larval “balls” in some potholes. The advantages of this behavior are not very clear, but it is still very impressive.

A damsel bug

Damsel bugs (family Nabidae) are slender creatures resembling miniature praying mantids in having raptorial front legs. Like praying mantids, their front legs are used to capture small prey, likely plant hoppers on the salt marsh. Damsel bugs have a long beak with which they suck out juices from insects they capture. The beak can also delivery a painful bite, if handled carelessly. These individuals are possibly nymphs, i.e immature true bugs since they don't have fully developed wings.

August - the battle of two predators 2

Praying or European mantis (Mantis religiosa) is the most common mantid on the salt marsh. As the name suggests, it is an introduced species that came to the US in the late 1800s. It is still popular for "pest control", a notion totally opposed to the non-specialized nature of the mantid hunting, in which both pests and beneficial insects are captured and consumed. Case in point is this photo, where European mantis has eaten several Seaside dragonlets, a very beneficial dragonfly.

Although Seaside dragonlets are fierce predators in their own right tirelessly patrolling the marsh for flies, mosquitoes, and other small flying insects, they are no match for the fearsome pincers of a large praying mantis female.

Parasitoids - the truely tiny

 Parasitoids, or insect consuming other insect but in moderation (usually just one) are frequently overlooked due to their small size, like a flying spec of dust. These tiny wasps search for eggs or small insects as a food source for their larvae.

End of July - The battle of two predators 1

Seaside dragonlet is among the most beautiful insects on the salt marsh. It is also among its deadliest. As an immature, which is called naiad for dragonflies, it is the top invertebrate predator in the potholes and on the mudflats, a hunter of other creatures.

   As an adult, seaside dragonlet eats whatever it can catch, mostly flies - mosquitoes, midges, syrphids and similar. But, the marsh surface is also a home to another deadly creature, the spider. Spiders are mostly generalist predators and take whatever comes their way, which usually means the most abundant insects at the moment. This year it's been dragonflies buzzing around in enormous swarms. Sadly, many ended up in the spider nets protruding from the salt marsh vegetation...