This year the OIF is bringing in some awesome new inverts to our product lineup and bringing a new section to the Farm: beneficial insects!
From back when I personally kept a bunch of different reptile and amphibians they were housed in different setups, from elaborate tropical planted terrariums to simple rock and sandy-loam. No matter how simple or complex the habitat, one thing that I and every keeper dreaded was the outbreak of a pest.
To deal with pests the most effective approach tends to be IPM, which stands for Integrated Pest Management. This is using a combination of chemical, biological, and culturing methods to combat pests and diseases. When used together in combination these methods offer the best way to deal with pests, whether in an agricultural setting or in your own terrarium.
Methods of combating pest outbreaks were (and still are) a bit more limited in the terrarium given the duel objectives to kill off the invaders while at the same time keeping the desirable species alive. Chemicals, while often effective at killing pests, tend to also be poison and hurt nontarget species and therefore are usually off the table, although natural choices such as tea tree or neem oils could potentially be explored.
Culturing methods can involve something as simple as letting the substrate dry out if dealing with fungus gnats, although this usually doesn't prove 100% effective and can be impractical in a planted tank or one housing amphibians.
Given these limits and also the enclosed nature of these environments one of the most effective methods to combat pests is the use of beneficial invertebrates.
Every species on this planet has natural limiters to keep them in check and to help create balance. When there is an overabundance of a species this represents an unused resource, and it is to be expected that eventually something will come to make use of it, whether that be a predator, parasite, disease, or parasitoid. This is no different for pests of the terrarium, indoor grow, or garden. In this fight our allies include natural predators and parasitoids of the whatever happens to be the species which is afflicting the spaces we tend.
The employment of disease causing agents can be seen to be effective, such as Bt bacteria. The use of mosquito dunks containing Bti has been shown to be useful against the larval stage of fungus gnat. The dunks are usually available through garden centers or online retailers, although the Bt bacteria can reportedly be cultured at home with some effort.
Many are more difficult to consistently propagate within the confines of the average terrarium, or even in a seperate setup and so the easier, more scalable choice is unsurprisingly predators and parasitoids.
A quick note on parasites and parasitoids- while they sound similar they have two very different modes of action and goals. Parasites, as most are familiar with, are creatures that live on or in another organism (the "host"), using it as a source of food while contributing nothing beneficial to the host in return. Another aspect of parasites is they require a host to complete their lifecycle.
Although they may weaken it, the goal of the parasite is not to kill its host. This is what makes them little use to us in the fight against pests. However, there is a more powerful force available to us in our battle; parasitoids!
Similar to parasites in that they require a host to complete their lifecycle, one of the major differences is that infection with a parasitoid is almost always fatal. The eggs of the parasitoid are laid on or in the host. Upon hatching the young enter the host and start feeding on the insides of their unfortunate host, starting with the least vital organs. Eventually their sickly host spins a cocoon or just dies. In either case eventually out pour new adult parasitoids, ready to mate and start the cycle anew.
In the outdoor garden the use of predators can be met with mixed results: praying mantids ootheca (eggs cases)and ladybird beetles are two commonly offered "pest control solutions" sold at garden centers. With mantids it has been found that they often feed on both pests as well as other beneficial insects - the mantis is only concerned with catching and eating food. In the case of the ladybird beetles, they are commonly collected from overwintering sites on the west coast and then shipped to garden centers to be sold. Upon release into the garden they may eat a pest or two but in many cases take off and disperse well away from the release site. So the use a many predatory, and even parasitoid, species in outdoor settings can of limited effectiveness and mixed results. However, when used in a contained space such as an indoor garden or terrarium the results are much more appreciable and effective.
The beauty of using parasitoids is that typically they have a narrow host range, and often even general predatory insects are fairly limited in their scope of what they will take as prey. This means that your pets, family members, and terrarium occupants are in no danger with the application of beneficials. Due to their containment and prey selectiveness beneficial insects and invertebrates are easily argued to be the best of the IPM options available to the those dealing with a pest outbreak indoors.
That said, the Ontario Invert Farm has turned our focus towards a selective number of beneficial inverts and propagating them for use in terrariums and on indoor plants. Species profiles and further info in relation to pest management is coming in a follow up post. If any readers have anything specific they'd like to have addressed with relation to terrarium pests, beneficial inverts, or related topics I encourage you to leave a comment below and I will do my best to ensure it gets attention in the coming post.
Thanks for reading!
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