Nematode Parasitism in Locusts
The desert locust, like many insects, can harbor roundworms called nematodes in its digestive tract or body cavity. These parasites are not transmissible to humans or domestic animals. This parasitism is of primary interest to acridology re...
What is it?
The desert locust, like many insects, can harbor roundworms called nematodes in its digestive tract or body cavity. These parasites are not transmissible to humans or domestic animals. This parasitism is of primary interest to acridology researchers and locust control authorities, as it can influence the survival and reproduction of locust swarms.
This is not a disease of concern in classical veterinary medicine, but it has significant ecological and agronomic interest in regions affected by desert locust invasions, such as the Maghreb and the Sahel.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Parasitized locusts often show few visible signs to the naked eye. However, general weakness of the insect, reduced activity, and slower growth in young stages (nymphs) may be observed, and sometimes abnormally swollen abdomen if the parasite burden is heavy.
In severe cases, infected locusts may show increased mortality, especially during periods of stress (food shortage, high population density).
These signs are not specific and require dissection to confirm the presence of nematodes.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Parasitism is caused by nematodes, particularly certain species of the genus Mermis or related families, which colonize the digestive tract or body cavity of the locust. The eggs of these worms are ingested by the locust while feeding on contaminated plants, or the larvae may penetrate directly through the cuticle (outer skin) of the insect in some cases.
Locusts living in humid areas or after rainfall are more exposed, as moisture promotes the development and survival of nematode eggs and larvae in soil and on vegetation.
High population densities of locusts, such as during swarms, also increase the risk of cross-contamination.
Young larval stages of the locust appear more vulnerable than adults.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
There is no standard veterinary diagnosis applicable to the desert locust. Identification of nematode parasitism is made by dissecting the insect to observe the worms directly in the digestive tract or body cavity, or by microscopic examination of faeces to detect eggs. This work falls under the expertise of entomologists and laboratories specialising in acridology, particularly the national locust control centres found in North Africa and the Sahel.
Treatment
There is no validated or practised antiparasitic treatment for wild locusts. In the context of controlled insect farming, hygiene measures and environmental management are favoured rather than direct medication.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There is no individual prevention measure for wild desert locusts. In the context of insect rearing (for animal feed for example), risks can be limited by controlling environmental humidity, preventing access to soil or vegetation potentially contaminated with nematode eggs, and maintaining good hygiene in rearing enclosures.
Possible complications
A high parasitic load can reduce the locust's flight capacity and reproductive ability, and increase mortality, particularly during periods of limited food resources. At the population level, this can play a natural role in regulating swarm numbers, though it is not sufficient to control locust plagues.
When to see a veterinarian
This section does not apply to the general public for this issue. In a research or insect farming context, unexplained weakness and abnormal mortality within a colony should prompt consultation with an entomologist or specialised laboratory.
Prognosis
The prognosis depends on the parasitic load. Light infestation is often well tolerated by the insect. Heavy infestation can reduce the locust's lifespan and reproductive capacity, though it is not necessarily fatal.
Frequently asked questions
Can grasshopper nematodes infect humans or domestic animals?
No, these nematodes are specific to insects such as the desert locust and pose no risk to humans, livestock, or pets.
Can parasitism be used to fight invasions of desert locusts?
Nematodes play a minor natural role in population regulation, but they are neither sufficiently effective nor controllable enough to constitute a large-scale locust control method.
How to tell if a cricket is parasitized? Look for these signs: - **Abnormal behavior**: The cricket may move erratically, seem disoriented, or display unusual postures (tilting its head, raised abdomen). - **Physical changes**: Look for lumps, swelling, or visible parasites on the body, particularly around the abdomen or joints. - **Weakness and lethargy**: A parasitized cricket often appears sluggish, moves slowly, or has difficulty jumping normally. - **Changes in appetite**: It may stop eating or eat less than usual. - **Visible exit holes**: Some parasites (like certain wasps) leave small holes where they've emerged from the cricket's body. - **Discharge or leakage**: Abnormal fluids from the body openings. - **Discoloration**: The cricket's coloring may appear dull or darker than normal. - **Loss of coordination**: Difficulty maintaining balance or walking in a straight line. The most reliable indicators are behavioral changes and visible physical abnormalities. If you suspect parasitism, isolate the cricket to prevent the parasite from spreading to others in your colony.
There is no reliable visible sign that can be detected by the naked eye. Only dissection or microscopic examination by a specialist can confirm the presence of nematodes.
Does this parasitism also affect other insects?
Yes, many insects, particularly other orthopterans (grasshoppers, crickets), can harbour similar nematodes, these parasites not being exclusive to the desert locust.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 31 August 2026
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