INVASIVE WASPS

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Picture Courtesy: https://www.downtoearth.org.in/africa/invasive-wasps-threaten-south-african-ecosystems-what-the-public-can-do-to-help-stop-the-spread

Context: Invasive wasps, including the German and European paper wasps, pose significant ecological and economic threats in South Africa, and public involvement through citizen science can help monitor and control their spread.

Details

• Invasive wasps pose a significant threat to ecosystems and economies worldwide. The problem has been highlighted in South Africa, where the presence of invasive wasps is becoming increasingly concerning.

About Wasps

• Order Hymenoptera: This is the larger insect order that includes wasps, bees, and ants. Hymenoptera insects generally have two pairs of wings and a characteristic body structure.
• Suborder Apocrita: Wasps belong to this suborder, distinguished by their narrow waist. This group also includes ants and bees.

Cladistics and Evolution

• Wasps as a group do not form a clade, which is a complete natural group sharing a single ancestor. Instead, bees and ants evolved from wasp ancestors, making them nested within the broader wasp lineage. A clade is defined by all members sharing a common ancestor, but in this case, the evolutionary relationships are more complex.

Behaviour and Social Structure

• Aculeata Clade: This subgroup within the wasps includes species that have a sting used for defence or capturing prey. Members of this clade are known for their ability to sting.
• Eusocial Wasps: Common examples like yellowjackets and hornets are eusocial. They live in colonies with a hierarchical structure:
  • Queen: The sole egg-laying female.
  • Workers: Sterile females that perform tasks like foraging and nest maintenance.
  • Eusociality: This behaviour is supported by the haplodiploid sex-determination system, where sisters are highly related (relatedness of 0.75), promoting cooperative behaviour.

Ecological Roles

• Predators and Pollinators: Wasps can be important predators of other insects and also play a role in pollination.
• Kleptoparasitism: Some wasps, such as cuckoo wasps, lay their eggs in the nests of other wasps, where their larvae consume the host’s eggs or larvae.
• Parasitoidal Behavior: Many solitary wasps lay eggs on or inside other insects. These wasp larvae eventually kill their hosts. This behaviour helps control pest populations, making them useful for biological pest control in agriculture.

Fossil Record and Diversity

• Historical Appearance: Wasps first appeared in the Jurassic period, with diversification into various superfamilies by the Cretaceous period.
• Global Distribution: They are found worldwide except in polar regions, demonstrating their adaptability and success.
• Size Variation:
  • Largest Social Wasp: The Asian giant hornet, reaching up to 5 cm in length.
  • Largest Solitary Wasp: Includes tarantula hawks and the giant scoliid of Indonesia (Megascolia procer).
  • Smallest Wasps: Includes solitary parasitoid wasps from the family Mymaridae, with some species being the smallest known insects, as small as 0.139 mm.

Current Invasive Wasp Species in South Africa ●German Wasp (Vespula germanica): ○Characteristics: This species is a generalist predator and scavenger, often seen around human food sources. They typically nest underground or in building vents. ○Spread: The German wasp was first recorded in Cape Town's Kirstenbosch Botanical Gardens in 1972 and has since spread, including a recent expansion into the Cederberg region. ●European Paper Wasp (Polistes dominula): ○Characteristics: This species nests above ground and can be identified by its orange antennae and the way it flies with its legs hanging. ○Spread: First detected in Kuilsrivier in 2008, this species has spread to other areas like Porterville and Hermanus. ●Asian Hornet (Vespa velutina): ○Threat: This species is highly invasive and preys on honey bees. It could be disastrous for South Africa's honey bee populations if it arrives.

The Problem

• Rapid Colonization: Invasive wasps like the German wasp and European paper wasp have established themselves in the Western Cape, with the German wasp even expanding its range.
• Ecological Impact: These wasps prey on a variety of insects, including beneficial species like honeybees. They can also damage crops and compete with native wildlife for resources.
• Economic Consequences: The agricultural sector can suffer significant losses due to wasp activity, as these insects can damage fruit and reduce pollination rates.

Challenges in Managing Invasive Wasps

• Monitoring Difficulties:
  • Resource Constraints: Limited funds and a shortage of invasion biologists make it challenging to monitor and manage invasive wasp populations effectively.
  • Eradication Costs: Eradicating established wasp populations is expensive and complex, especially as they become entrenched in ecosystems.
• Spread to New Areas:
  • Risk of Expansion: The continued spread of invasive wasps poses a risk of moving into new provinces and potentially causing further ecological and economic damage.

How the Public Can Help ●Citizen Science Involvement: ○Using Technology: With a smartphone equipped with GPS and a camera, members of the public can contribute to monitoring efforts. ○Reporting Observations: By photographing and uploading images of wasps to citizen science platforms like iNaturalist, the public can assist scientists in tracking and studying wasp populations. ● Benefits of Citizen Science: ○Data Collection: Citizen science platforms can gather extensive data on wasp distribution, aiding in research and early detection of new invasions. ○ Biodiversity Research: Contributions from the public are valuable for understanding and managing biodiversity, especially in tracking invasive species.

Conclusion

• The invasive wasp species in South Africa, particularly the German wasp and European paper wasp, present serious challenges to local ecosystems and economies. The potential threat of the Asian hornet further highlights the urgency of managing these invasive species. Citizen science plays a crucial role in monitoring and controlling these threats. By engaging in these efforts, the public can help mitigate the impacts of invasive wasps and contribute to the preservation of South Africa’s biodiversity.

Source:

Down To Earth

Wikipedia

PRACTICE QUESTION Q. How many of the following characteristics are commonly associated with invasive species? 1. High reproductive rate 2. Specialized habitat requirements 3. Lack of natural predators 4. Limited dispersal ability Select the correct answer using the codes given below: A) Only one B) Only two C) Only three D) All four  Answer: B