International Archives of Health Sciences (Aug 2024)
Lizards: Poisonous animals or biological pest control agents?
Abstract
The lack of accurate understanding of the environment and its surrounding fauna has led to the spread of misconceptions about the behaviors of certain animals, such as lizards. This is evident even in articles that lack scientific rigor. For instance, one article claims that the painful bites of lizards can cause fear and infection.[1]Additionally, many people believe that lizards possess poisonous tails, leading to the erroneous assumption that if they were to fall into cooking pots and be consumed, it could result in death due to cyanide poisoning. Such beliefs, particularly regarding Iranian lizards, are unfounded. This fear is largely rooted in superstition; it is important to note that lizards do not pose a threat to human life. They are completely harmless creatures, and even when captured or trapped, they do not endanger humans. Over the past 35 years, various species of Iranian lizards-ranging from 2 to 80 centimeters in size-have coexisted in both natural environments and traditional and modern homes without causing any harm [Figure 1].This fear is entirely baseless and primarily stems from cultural misconceptions that should be addressed through public awareness initiatives. Lizards are not merely pests; they are also among the best biological pest control agents.[2,3] They can effectively hunt mosquitoes for hours behind window screens in homes. As some of the most efficient insectivores, lizards have adapted well to a variety of habitats, including deserts, mountains, forests, and both urban and rural residential areas, without causing any harm or damage. They play a vital role in controlling pests such as cockroaches and mosquitoes.[4] However, awareness of the benefits of these creatures in Iran remains low.Having a lizard in the house is akin to hiring someone to tirelessly combat household pests day and night-without incurring any expenses, chemical pollution, or the need for management and supervision.[5]While some lizards are venomous, they belong to specific families. The Iguanidae family includes the green iguana (Iguana iguana), which has a weak venom and is found from Mexico to Brazil. The Helodermatidae family features well-known venomous species such as the Gila monster (Heloderma suspectum), which inhabits areas in the southern United States-including Arizona, California, Nevada, Utah, New Mexico-and parts of Mexico such as Sonora and Sinaloa, as well as Guatemala's borders. Human bites from these lizards are rare, with the last reported death occurring in 1939.[6,7]A significant number of venomous species have been reported within the Varanidae family. Among them is the West African Nile monitor, Varanus niloticus stellatus, which possesses mild and harmless venom. The Crocodile monitor, Varanus salvadorii, native to the islands of New Guinea, is known for its invasive nature. Another notable species is the Malayan water monitor, Varanus salvator, which has been reported in regions such as Bengal, Sri Lanka, and China. The Komodo dragon, Varanus komodoensis, is one of the largest lizards in the world and inhabits the Komodo Islands of Indonesia.[8,9] Recent studies have identified 171 lizard species in Iran, three of which belong to the Varanidae family. While many of the world's venomous lizard species are part of this family, no venomous species have been documented in Iran to date.[10,11To date, there has been no documented evidence indicating that Iranian lizards are poisonous or venomous. Many individuals mistakenly believe that lizards shed their tails to distract predators, leading to the predator's demise due to toxins such as cyanide or other harmful substances. Occasionally, we hear unfounded claims that people have died after a lizard fell into a pot of food or a milk churn.Some researchers have demonstrated that ingesting domestic lizards in Iran does not result in any poisonous effects, such as nausea, diarrhea, stomach pain, drowsiness, dizziness, weakness, high fever, chills, loss of appetite, headaches, irritability, difficulty swallowing (dysphagia), breathing difficulties, excessive salivation, skin rashes, cyanosis (blue lips and skin), burns around the nose or mouth, double vision or blurred vision, mental confusion, seizures or convulsions, loss of consciousness, or coma.[12]The fear or phobia of lizards, similar to apprehensions regarding other phenomena, is widespread globally and manifests in hundreds of phobia types across various cultures and geographical regions. The role of researchers is not to endorse or validate these unfounded fears stemming from ignorance but rather to educate the public about the true nature of these creatures. Education should begin at the earliest stages of life. It is notable that while most members of society may enjoy seeing a sheep's head in a pot, they often express concern about having a lizard in their home. This reaction is not inherent but rather a set of cultural behaviors passed down through generations. If this fear and discomfort regarding lizards become widespread, it could exacerbate the situation. Certainly, we know individuals who may have sensitivities or aversions to certain foods or fruits; however, these sensitivities often diminish over time with increased experience or knowledge.Lizards play a crucial role in ecosystems, particularly in controlling rodent populations. By preying on rodents, they help maintain balance within the food web and contribute to the overall health of their environments. This ecological function is especially important in agricultural settings, where rodent infestations can cause significant crop damage and economic losses.The reliance on chemical pesticides for pest control has raised numerous environmental concerns. Pesticides can have detrimental effects on non-target species, including beneficial insects, birds, and aquatic life. Additionally, the need to change pesticide formulations over time often leads to the use of more potent chemicals, further harming ecosystems and potentially impacting human health.In contrast, biological control methods-such as using natural predators like lizards, rodents, and predatory birds-offer a more sustainable approach to pest management. This method not only reduces reliance on chemical pesticides but also promotes biodiversity and enhances ecosystem resilience. By integrating lizards into pest management strategies, farmers can harness their natural predation abilities, resulting in healthier crops and improved public health outcomes.Furthermore, fostering lizard populations in agricultural areas can decrease the prevalence of pests that transmit diseases to humans and livestock, underscoring their importance in maintaining ecological balance. As awareness of these benefits grows, more agricultural practices are likely to incorporate biological control methods, recognizing the invaluable contributions of lizards and other natural predators to sustainable farming and environmental health.Lizards primarily feed on rodents, making them a vital natural control factor for rodent populations.[9] Consequently, they hold significant ecological value within the energy pyramid. By removing lizards from the natural ecosystem, humans would eliminate one of the key players in maintaining population balance.Experts in agricultural and environmental sciences have concluded that the use of pesticides for pest control should be minimized due to their harmful effects on the environment. Furthermore, every few years, the types of pesticides used must be changed to maintain their effectiveness against pests, often resulting in the application of stronger chemicals that exacerbate environmental damage.In response to these challenges, humans have increasingly turned to breeding and utilizing various natural predators, such as lizards, rodents, and predatory birds, to combat agricultural pests. This approach, known as biological control, is now widely adopted in many countries. By controlling populations of both agricultural and health-related pests, lizards play a crucial role in enhancing public health and increasing crop yields.[5,9]
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