Locusts: A Prevalant Issue and Newer Solutions
Locusts are historically known for their catastrophic damage to farms, and the first recorded instances of locust swarms was recorded in 3200 B.C.E in Egypt. Locusts can create swarms of billions of locusts, and are a major detriment to communities in Somalia, Ethiopia, Egypt, Iraq, and India. In 2020, the species Locusta Migratoria or “Migratory Locust,” has devastated farms, moving from East Africa to India. It is labeled as the highest priority threat according to the United Nations Food and Agriculture Organization. Worse, is that these swarms are congregating more often, and many of the world’s leading pesticides are being outlawed from usage.
Recently the Indian government decided to outlaw the use of organopesticides; pesticides that interfere with the production of a vital hormone called cholinterase in animals and humans, and the pesticide is absorbed through the skin. Common pesticides include Dychlovros, Fipronil, and Timoril, each of which are toxic for consumption. All of these pesticides if consumed can cause death by suffocation, and many of these pesticides are unaffordable to communities in East Africa. So what is an alternative solution?
A New Pesticide
To provide context, Locusts have two different phases, the solitary and the gregarious phase. The majority of a locust’s life is in the solitary phase, where locusts are completely harmless and contribute to the ecosystem. The gregarious phase allows locusts to reproduce, congregate, intake more nutrients, and grow wings. It is a metamorphic response to two factors: moisture, followed by increased population density. This phase allows locusts to adapt to areas that don’t rain for years.
With the increasing intensity of the humidity due to climate change, this response can be repeated.
Recently, Scientists have made a breakthrough in locust research for the species. The gregarious phase is activated by the movement of the hind legs, which helps attract locusts. Scientists have learned that this stimulates the production of a hormone called 4-vinalysine or 4-VA ,in turn stimulates the production of dopamine, and then produces a protein called OR35 to detect the same hormone from other locusts in order to congregate and multiply. Then as the population multiplies, swarms begin to form and become attracted to each other.
A possible use for the discovery of 4-vinalysine would be to divert the swarm to an area without damaging the population. Scientists have experimented with this hormone to possibly use the hormone as a way to divert the locusts swarms away from a particular area, and has been relatively effective. However, it may not be the most effective pesticide; While the Migratory Locust may use 4-vinalysine, The Australian Plague Locust may utilize another hormone to detect other locusts during its gregarious phase . It would be incredibly risky if the pesticides that farms used were only effective against one species of locust.
An Older Hypothesis
Since 1999, the scientific community has believed that using Juvenile Hormones, or a class of hormones that develop the adult form of insects, is ineffective on the species Locusta Migratoria. According to studies done at the Academy of Sciences in Xinhua, The juvenile hormone Neotenin can be utilized to revert the gregarious form to the solitary phase, and relatively more effective at suppressing gene expression.
During this study, contained groups of gregarious locusts were exposed to different juvenile hormones. Many of these hormones could revert only a fraction of the tested population, some of which died. Others had a higher death rates, and some could effectively revert the majority of the population. After the locusts were exposed many of them reentered their solitary phase, indicated by the behavioral response of trying to separate themselves from other locusts. Juvenile Hormone was concluded to be the most effective, in terms of gene suppression
Neotenin is an essential hormone in the development and plasticity of Locusts as well as several other insect species. Produced in the corpora allata as part of the endocrine system, Neotenin influences the process of molting, and is necessary for females to produce eggs. Juvenile Hormone is primarily known for inhibiting insect metamorphosis, and its most common form is JH III.
Juvenile Hormone suppresses aggregation behavior by depressing antennal gene receptors that detect 4-vinalysine.
While Juvenile Hormone may be an effective substance, it could produce unintended consequences. Juvenile Hormone is an essential hormone that may affect the reproduction of the species.
Genetic Engineering
Scientists at Yale have been consistently experimenting with genetic engineering on insects since 1999, discovering the first olfactory gene receptors in insects. The gene receptors activate an insect’s sense of color, smell, and perception. Since locusts possess the gene that creates the protein OR35, it is possible to suppress this gene to create a grasshopper that remains with its solitary phase. However, there is no way to preserve an entire population of locusts that depend on the gregarious phase for reproduction.
Conclusion
While there are some potential solutions that do not necessarily require the destruction of the locust population, many of these solutions may have unintended consequences that may be destructive. The primary goal of this research is to find ways for humans and locusts to coexist; eventually, there will be no need to utilize pesticide.
