In nature, grasshoppers face unseen threats from an array of parasites. In this article, we’ll explore these hidden foes, ranging from mind-controlling fungi to body-hijacking nematodes, revealing a detailed list of 5 grasshopper parasites.
Worms
Like the praying mantis, grasshoppers are also parasitized by worms. However, they are not affected by the horsehair worm Chordodes formosanus. These species are affected by hairworm Spinochordodes tellinii and roundworm Nematodes.
Spinochordodes tellinii is a kind of parasite hairworm that infects grasshoppers and crickets. Its larvae get into water creatures, which are later eaten by grasshoppers and crickets. Inside the insect, they grow, sometimes becoming much longer than the insect itself. When they’re grown up, the worm makes the insect jump into water, so it can extract from the host body and find another worm to mate with, starting a whole new life cycle again.
Scientists found that the parasite makes proteins that mess with the host’s central nervous system. When grasshoppers and crickets get infected, their brains start making different proteins than usual. These proteins mess with stuff like how their nerves work and how they react to gravity, making them act weird and jump into the water, which is opposite to their instinct.
On the other hand, the nematode parasite, specifically Mermis nigrescens, is a type of roundworm. These grasshopper parasites can grow up to 20 cm long and are mostly pale brown with reddish-brown heads in females.
Grasshoppers get infected by Mermis nigrescens when they eat the nematodes’ eggs on plants. Once inside the grasshopper, the young worm burrows into its body, feeds on its blood, and grows. The bigger the grasshopper, the faster these worms grow inside it. And interestingly, smaller grasshoppers tend to have more male worms compared to bigger ones.
This type of roundworm doesn’t control grasshoppers and makes them commit suicide. But it makes the grasshopper very sick and can even cause it to die early or become unable to lay eggs. When the host dies, the nematodes leave it and go into the soil. There, they grow into adults and come out to lay eggs on leaves. This process keeps repeating. Mermis nigrescens likes moist places, especially wet grassy areas.
Parasitic flies and wasps
Small wasps attack these insects at various points in their lives. For instance, Scelio wasps lay their eggs inside grasshopper eggs, and when the eggs hatch, the larvae feed on these eggs from within, reducing their numbers. Similarly, other types of flies, like flesh flies and tachinid flies, also prey on grasshoppers.
Anisia serotina is a type of fly that attacks the eastern lubber grasshopper, Romalea microptera. It lays its eggs on or near the insect, and when the eggs hatch, the larvae enter the grasshopper’s body and eat its insides, which eventually kills it. These flies can be really effective, with up to 60-90% of grasshoppers getting infected.
There are other parasitic flies like Blaesoxipha opifera and Blaesoxipha hunter that also target these grasshoppers. Together, these lubber grasshopper parasites help control the grasshopper population and stop them from causing too much damage to plants and crops. So, they’re like natural pest controllers, which is good for farmers and the environment.
Mites
Grasshoppers are also parasitized by mites. The mite parasite in grasshoppers Eutrombidium locustorum attaches to grasshoppers by piercing their integument or wing veins, feeding on hemolymph, and remaining attached for 5-14 days. Another grasshopper parasite mite species is the grasshopper mite larvae (Arachnida: Trombiidae), which are observed as small red spots on the bodies of grasshoppers and can reduce the grasshoppers’ reproductive ability and interfere with their mobility, making them more vulnerable to predators.
Fungi
Last but not least – fungi, are one of the worst grasshopper parasites. There are several species of fungi that attack grasshoppers, including Entomophaga fungus (Entomophaga grylli, Entomophaga macleodii, Entomophaga calopteni), Verticillium lecanii, Nomuraea rileyi, and Paecilomyces sp, and Cordiceps fungus.
When a grasshopper comes into contact with the spores released by these fungi, typically from a fruiting body, the spores infect the insect. Inside the grasshopper’s body, the fungus grows thread-like structures called mycelium, which eventually lead to the death of the grasshopper. After killing the host, the fungus emerges from the grasshopper’s body to release more spores.
For example, Cordyceps locustiphila and Ophiocordyceps unilateralis are fungi that infect insects like grasshoppers. They take over the insect’s body, using it for food and shelter. Eventually, they cause the insect’s death and release spores to spread and infect other insects. These fungi change the behavior of the insects they infect, making them climb to high places before they die, which helps the fungi spread their spores better. This happens when fungi interact with the host’s nervous system, showing how parasites can control their hosts to help themselves.
Fungi from the Entomophaga genus infect grasshoppers and change how they act. They’re the most common grasshopper pathogens in North America and cause disease in grasshoppers known as “summit disease.” Infected grasshoppers climb to high spots like plant tops or fenceposts, where they die with their legs wrapped around the plant and heads up. This strange behavior helps spread fungal spores far and wide.
The E. grylli complex includes at least 3 types that infect different grasshopper species. These fungi have a complicated life cycle. They produce resting spores and asexual conidia. They infect grasshoppers when it’s wet and humid, causing several infections in one season.
Those are 5 grasshopper parasites, from wasps, flies, worms, fungi, to microsporidian parasites like Nosema locustae. They transmit infection to insects either through direct contact or via contaminated vegetation, resulting in a reduction of grasshopper populations by as much as 60%, thereby inhibiting their reproduction and mobility.
