Thomas J. Watson Fellowship Year

Raising Millions of Wasps

Migrating around the world over the past few months has set me in places I previously only fantasized about and has allowed me to meet people whose passion for insects has developed into successful businesses. One such business and my personal dream job was found just outside Brisbane where I helped raise millions of parasitoid wasps for the biological control of pests in Australia. While I had once only studied these wasps in their dead form under a microscope, I was finally working with live specimens in exchange for accommodation.

Richard Llewellyn of BioResources Queensland is always surveying crops for the effectiveness of his wasps and making sure no new pests arise.


But why would we be raising these wasps and selling them to farmers by the thousands? The answer lies in the wasp’s ecology. Hold on for a moment as we make a trek down complex ecology lane: a parasitoid wasp is a type of parasite. All parasites require a host for survival. A tapeworm will not kill you as it enjoys all the meals you add to your tummy, but a parasitoid will feed on a host and then kill it as a result of the interaction. Parasitoid wasps normally carry out this hardcore life by first laying their eggs inside of another insect, those eggs then hatch into larvae which feed internally until they grow fat enough to pupate into adults where they will then leave their host, spin a cocoon, and slowly turn into a beautiful…wasp! Meanwhile, the host is eaten from the inside out. Remind you of the 1979 horror film, Alien? It was the inspiration for it!

 

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Anastatus wasps emerging from parasitized silk moth [Bombyx mori] eggs
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The black are parasitized eggs with Trichogramma wasps

 

 

This somewhat horrific survival strategy is incredibly useful though. It is estimated that for every insect, there is a wasp that parasitizes it. It’s a natural way that insect populations are kept in check and one alternative method to using pesticides. To fight nature with nature or biologically control your pest population, you can release the appropriate wasp species on your farm by the thousands. This high parasitoid population will then match that of your pests until the pest population is eliminated.

 

One small nut on a large Macadamia farm.

Card mounted representatives of the Anastatus wasp, a biocontrol agent for the fruit spotting bug [Amblypelta spp.]
If frightful flashes of cane toads are blurring your vision right now, take a deep breath and consider how many parasitoid wasps are host-specific. Host-specificity constricts wasps from being able to parasitize a range of insects, instead they can only lay their eggs in one host. Once the host is gone, so is the wasp-weapon as the next generation can no longer be sustained. The main problem with using the cane toad in Australia for biological control was that these animals are generalists and were able to prey upon non-pest animals then spread throughout the local ecosystem to where it is still a prevalent issue 82 years later.

 

Fat and healthy female cane toad found in rainforests near Mackay.
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See just how teeny tiny the Anastatus wasp is in real life? This is on my pinky finger!

Ah, and now, the dream job: raising millions of these wasps for biological control. To raise the wasps we must first raise their host insect: a silk moth, fruit spotting bug, or green vegetable bug. Once we had a host, we would let some of our adult wasps parasitise the eggs of the first group of insects. These parasitised eggs were then packaged and sent to farms throughout Queensland and New South Wales to various tropical farmers so they may release the adult wasps which emerge. But why would farmers want these tiny wasps by the thousands?

Silk moth [Bombyx mori] eggs, parasitized with Anastatus wasps and ready for shipment.

Since the shocking discoveries of DDT’s effects on the environment, alternative options to using pesticides have been investigated. Rachel Carson featured the horrific effects of the pesticide DDT in her book, “Silent Spring,” whose namesake is from the story of the effects of this pesticide on the surrounding environment. DDT successfully killed the insect pests of several crops, but surrounding birds would then gobble up these poisoned prey, transferring the DDT into their own system and then produce weak eggshells. These fragile eggs were so delicate that they were crushed beneath the mother bird’s weight when she tried to sit over them to keep them warm. Unable to support the development of the baby birds, the populations of several birds plummeted and the surrounding springs were left silent without birdsong. Alongside the wildlife, increased cases of leukemia and other forms of cancer among farmers also correlated with the use of DDT.

Now banned in most countries, the negative effects of DDT motivated scientists around the world to research alternatives to chemical pesticides for controlling agricultural pests. The resulting area of research was biological control, which is best summarised as nature fighting nature. Popular biological control agents are fungi and insects, with parasitoid wasps having the most success in controlling pests in the past. These wasps work well in biological control because their biology requires them to lay their egg inside of a host insect. When a particular insect pest invades a crop, you can find and raise the wasp that parasitises your pest insect. Once the wasp population is large enough, it can be used to eliminate the pest population by simple releases on the crop. What keeps these wasps from spreading are their host specificity. Unlike cane toads and other biological control agents, most parasitoid wasps have coevolved with one host insect for millions of years. Once the pest is eliminated, the wasp can no longer lay its eggs, and should die off as well.

Finding this particular wasp, raising it and its host, then making a business out of this process however takes a unique skillset and an immense amount of passion. Thankfully, Richard Llewellyn was able to use his personal interest in insect ecology and background in anthropology to develop such a business called BioResources Queensland. For over 30 years, Richard has been collecting and raising different varieties of wasps. He has worked with scientists to assess different wasps as biological control agents and developed methods and facilities for raising millions of these wasps. Such a place may sound terrifying, but it is important to know that these particular wasps are small. Sizes of the different species ranges from as large as 4 millimeters to as small as 1mm. Even the largest species, Anastatus spp., which I confirmed to be undescribed and therefore new to science, can get stuck in your hair where you don’t notice them until you’re home and having tea on the veranda with your host mom.

While I worked in Llewellyn’s insectary, I helped feed, clean, and package wasps. Richard also appreciated my help in identifying the diversity of insects he found on Macadamia nut farms while I enjoyed getting to learn new insect catching techniques and all the different groups in the area. Richard appreciated my help so much, that he brought me along to visit Macadamia nut and avocado farmers who used his wasps. A new pest, the Sigastus weevil was starting to invade Macadamia farms while I was volunteering at BioResources QLD, and farmers were happy to share all their knowledge of this pest. Speaking with the farmers solidifies Richard’s relationship with them as customers and keeps each party informed about current pests and how to treat them. A high degree of trust is involved in this process and no farmer would be using wasps to control pests if Richard wasn’t diligent in teaching and visiting farmers regularly. Learning the value of relationships between scientists and farmers, I made some farming friends of my own and engaged in an equal exchange of knowledge, insects for farming. It was an incredibly enlightening experience and further confirmation for my future career in biological control.

I also began the search for the new parasitoid wasps which can be used to control the Sigastus weevil and started raising the weevil at our insectary with a special blend of oatmeal to replace the Macadamia nut that these weevils feed on. In this way, I was starting the whole process anew: problem pest, search for parasitoid, raise host, parasitize host, raise wasp, repeat. It may sound simple, but constant creativity is necessary when raising insects because each insect is different and discovering these differences requires a patient eye. Learning this process is completely experiential and impossible to have learned properly in a formal classroom. Through constant experimentation, Richard has developed 8 different buildings to house each different insect and the methods for raising them successfully. These methods are carried out by 7 staff members, each of whom flow together smoothly like worker ants.

In exchange for my work, I got to live and eat at Wanda Trevor’s house at the base of Mount Samson. A French intern of my same age, Alizee also lived on this farmstead and we would spend each morning watching the sunrise and drinking coffee before we carpooled with Shane, the organiser of the insectary, and Richard to Woodford. Alizee and I were in constant awe at how lucky we were. Our job was full of creative, happy people, while the work itself was different each day and Wanda’s house became our home as we spent time with Wanda’s cousins, parents, children, and local friends. The home itself was teeming with life and pollinators as Wanda raised cottage plants and didn’t mind sharing her home with local geckos and spiders who wandered through. My hobby of night hiking and insect photography was well fostered here, alongside my skills in cooking from scratch. From French toast and quiche to apple pie and vegetarian chili, Allizee and I enjoyed cooking at Wanda’s with some of our dinner parties reaching eleven people!

Allizee, Wanda, and I all cried when I had to leave for Thailand. The hardest part of this year is making close friends and finding a place where I can foster my interest in entomology, then having to pack up and leave because it is time to go. I strongly believe I will continue my work in the biological control of Macadamia nut farming with parasitoid wasps and use everything I have learned while in Brisbane, Samford and Woodford, Queensland. The process of studying wasps in the field and how they can be both useful to farmers and sparing of the rainforest surrounding the farms has become one of my greatest passions. I care for the wellbeing of the Australian land and people as I feel like I’ve found more of a home there than I have ever known before. Once while night spotting for wildlife on top of my friend’s van, I looked up at the stars and surrounding Eucalyptus trees and wondered how I was born so far away.

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