While you’re out scouting for cutworms, tachinids flies and ichneumonid wasps are scouting for them too! We have two Insects of the Week this week and both are parasitoids of cutworm pests. Parasitoids complete part of their lifecycle inside another organism, in this case cutworms, eventually killing them.
Adult tachinid flies are pale or dark brown in colour with long, bristly hairs covering their bodies. Females typically lay one to several eggs on a host. Upon hatching the larvae burrow into the host, develop inside, and then exit to pupate in the soil. Adult flies feed on flower nectar, honeydew from aphids, scale insects, and mealybugs. The tachinid, Athrycia cinerea (Coq.), is a parasitoid of the Bertha armyworm.
An adult tachinid fly (Tachinia algens) reared from glassy cutworm. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm.
Ichneumonidae adults vary in size and colouration but all have a narrow waist, a long abdomen, and long antennae. Females have long ovipositors that they use to inject eggs into their hosts, including cutworm larvae. Adults eat nectar and aphid honeydew. Ichneumonid larvae (including Banchus flavescens) are parasitoids of Lepidoptera, Coleoptera, Diptera, Hymenoptera, and some spiders.
An adult Ichneumonid parasitoid of the genus Banchus, reared from a dingy cutworm. Photo credit: Shelby Dufton, AAFC-Beaverlodge Research Farm.
For more information about these parasitoids, the other pests they control and other important crop and forage insects, see the Field Crop and Forage Pests and their Natural Enemies in Western Canada guide. The guide has helpful information about the life cycle of these and other parasitoids. The guide also has tips for conserving parasitoids and pictures to help with identification.
The NEW Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops.
Two NEW Field Heroes resources for 2021 include:
The NEW Pests and Predators Field Guideis filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Two NEW Field Heroes resources for 2021 include:
The NEW Pests and Predators Field Guideis filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Two important NEW resources for 2021 include:
The NEW Pests and Predators Field Guide is filled with helpful images for quick insect indentification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
2. Real Agriculture went live in 2021 with Season 2 of the Pest and Predators podcast series!
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Real Agriculture went live in 2020 with a Pest and Predators podcast series!
• Access Episode 1 – Do you know your field heroes? Jennifer Otani (Agriculture and Agri-Food Canada-Beaverlodge) and Shaun Haney (RealAg). Published online May 12, 2020.
• Access Episode 3 – How much can one wasp save you? Haley Catton (Agriculture and Agri-Food Canada-Lethbridge) and Shaun Haney (RealAg). Published online June 9, 2020.
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Real Agriculture went live in 2020 with a Pest and Predators podcast series!
• Access Episode 1 – Do you know your field heroes? Jennifer Otani (Agriculture and Agri-Food Canada-Beaverlodge) and Shaun Haney (RealAg). Published online May 12, 2020.
• Access Episode 3 – How much can one wasp save you? Haley Catton (Agriculture and Agri-Food Canada-Lethbridge) and Shaun Haney (RealAg). Published online June 9, 2020.
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Real Agriculture went live in 2020 with a Pest and Predators podcast series!
• Access Episode 1 – Do you know your field heroes? Jennifer Otani (Agriculture and Agri-Food Canada-Beaverlodge) and Shaun Haney (RealAg). Published online May 12, 2020.
• Access Episode 3 – How much can one wasp save you? Haley Catton (Agriculture and Agri-Food Canada-Lethbridge) and Shaun Haney (RealAg). Published online June 9, 2020.
The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
Is that a midge or a parasitoid? Why does it matter?
Small insects (i.e., less than 5 mm) are difficult to identify, even for trained specialists and professional entomologists. Especially if they are alive, flying around. Or in a sweep net sample quickly assessed in the field. In the case of midge and small-bodied parasitoids, they can be easily mistaken for one another, but their roles in agriculture tend to be very different.
Some of the most well-known prairie midge species are agricultural pests, such as the orange coloured wheat midge (Sitodiplosis mosellana), black-coloured Hessian fly (Mayetiola destructor), and alfalfa blotch leafminer (Agromyza frontella). Other midge species found on the prairies include biting midge like no-see-ums (Ceratopogonidae), black flies (Simuliidae), and non-biting midge (Chironomidae). Midge that are not considered agricultural pests may provide some ecosystem services (i.e., pollination), while other midge are disease vectors and are pests of medical and veterinary concern.
A – Hessian fly – adult Scott Bauer, USDA Agricultural Research Service, Bugwood.org B – Swede midge – adult Susan Ellis, USDA APHIS PPQ, Bugwood.org C – Wheat midge – adult Mike Dolinski, MikeDolinski@hotmail.com
Parasitoids are natural enemies of other insects. Thus, many parasitoids are important because they help control agricultural pest populations. Adult parasitoids lay eggs, usually singly, onto or into their host. The larvae that hatch from the eggs develop using the host as food, and eventually kill the host. An individual host usually provides enough food for just one parasitoid larva. For this reason, parasitoids species are rarely larger in size than their host species. On the prairies, important parasitoid families that may be mistaken for midge or other small, black insects include: Aphidiinae, Braconidae, Chalchididae, Encyrtidae, Eulophidae, Platygasteridae, Pteromalidae and Trichogrammididae. Sticky cards or sweep net samples may contain hundreds or thousands of small, black, winged insects. Many are probably parasitoids and not pests so look closely when scouting. A few key differences to watch out for include:
Parasitoids have two pairs of wings while midge have only one pair of wings
Parasitoids are often shiny or metallic shades of black, blue, purple or green
Midge may look hairy; parasitoids rarely look hairy.
1 – Aphidiinae – adult (Aphidius avenaphis) Tyler Wist, AAFC 2 – Braconid wasp – adult Alberta Agriculture and Rural Development 3 – Chalcid wasp – adult (Phasgonophora sulcata) Michael Gates, Encyclopedia of Live, EOL.org 4 – Tetrastichus julis – adult parasitizing a cereal leaf beetle larva Swaroop Kher, University of Alberta/AAFC 5 – Ichneumonid – adult (Banchus flavescens) John Gavloski, Manitoba Agriculture, Food and Rural Development 6 – Platygasterid – adult (Inostemma sp.) Tyler Wist, AAFC 7 – Pteromalid – adult (Pteromalus puparum) Koorosh McCormack, Natural History Museum: Hymenoptera Section, EOL.org 8 – Trichogrammid – adult (Trichogramma sp.) parasitizing an egg Jack Kelly Clark, University of California Statewide IPM Program
This week’s Insects of the Week are the natural enemies (@FieldHeroes) of the wheat stem sawfly, namely Bracon cephi (Gahan) and B. lissogaster (Hymenoptera: Braconidae).
Nine species of parasitic wasps are known to attack wheat stem sawfly but Bracon cephi and B. lissogaster are the main species that help regulate this pest in North America. These closely related wasp species are described as idiobiont ectoparasitoids meaning the parasitoid larva, after hatching from an egg laid on the surface of the sawfly larva, feeds on the exterior of the host. Normally, both Bracon species will complete their development (i.e., pupates) inside the wheat stem within the integument of the sawfly larva or just beside the consumed host. There are two generations of B. cephi and B. lissogaster per year. The first generation normally completes its lifecycle then escapes from the wheat stem to locate a new sawfly larva to parasitize. The second generation of these wasps will overwinter within the wheat stem.
These wasps are 2-15 mm long and are usually brown in colour. They have a narrow waist connecting the abdomen to the thorax and the combined length of head plus thorax is equal to the length of the abdomen. These parastiod wasps have long antennae and two pairs of transparent wings. Females have a noticeable ovipositor protruding from the end of the abdomen.
For more information about the natural enemies of the wheat stem sawfly, check out our Insect of the Week page!
This week’s Insects of the Week are two parasitoid wasps, an Inostemma sp. (Hymenoptera: Platygastridae) and a Gastrancistus sp. (Hymenoptera: Pteromalidae). These parasitoids are natural enemies of the canola flower midge (Contariniabrassicola, Diptera: Cecidomyiidae), a newly discovered fly species that uses canola as its host plant. The parasitoids have been found throughout the Prairies emerging from infested galls created by the canola flower midge. Little is known about these two species, but parasitism rates as high as 30% have been noted in northeast Saskatchewan.
Populations of pea aphids, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), can be kept below the economic threshold by their natural enemies if these are present early and in sufficient numbers. Natural enemies include parasitoids, predators, and diseases that reduce pest populations.
Predators of pea aphids include ladybird beetles (adults and larvae), syrphid fly larvae, and damsel bugs. These predators catch and eat pea aphids of all ages and sizes. They are classified as generalists because they also prey on other insect species.
Harlequin ladybeetle larva (Photo: cc by-sa Quartl)
Pea aphids are attacked by several species of parasitoid, including Aphidius ervi Haliday (Hymenoptera: Aphidiidae: Aphidiinae). Female parasitoids lay individual eggs inside aphid nymphs. After hatching, the parasitoid larva consumes its host, eventually killing it. The parasitoid pupates inside the dead or mummified aphid before a new adult parasitoid emerges.
Aphid mummies look bloated and discoloured compared to healthy adult aphids. Parasitism rates can be estimated by counting the number of aphid mummies on five host plants at five locations within a field.
Aphidius ervi parasitoid (Photo: cc by Penny Greeves)
For more information about the predators and parasitoids of pea aphids, visit the Insect of the Week page or consult Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management Field Guide.
To learn more about some of the natural enemies fighting pests in background for free, go to www.fieldheroes.ca or follow @FieldHeroes on Twitter.
Blog post submitted by Dr. Meghan Vankosky. Follow her at @Vanbugsky.
The cabbage seedpod weevil is a chronic pest of canola in southern Alberta and south western Saskatchewan; it has recently reached Manitoba as well. The pest is managed with insecticides, which are sprayed at early flower. This year, in some canola fields around Lethbridge AB, an abundant parasitoid wasp was noticed at the time when fields may be sprayed. The wasp was identified as Diolcogaster claritibia (Fig. 1; thanks to Vincent Hervet and Jose Fernandez for confirming identification).
The wasp is a parasitoid that attacks diamondback moth larvae and recently abundant in some fields in 2017. In some of the fields sampled, as many parasitoids as cabbage seedpod weevil (i.e., nearly one per sweep) were observed. In the fields sampled (i.e., around 10), cabbage seedpod weevils were below thresholds on average, though some spots may have been close to the threshold of 2-3 weevils per sweep.
The above observation emphasizes the value of beneficial arthropods like Diolcogaster claritibia. It is important to recognize that foliar applications of insecticides kill beneficial insects like this small wasp (about 2 mm) which attacks and helps regulate pest populations of diamondback moth or other Lepidoptera, including cutworms and cabbage worms. Thus, think beneficials before you spray!
Figure 1. Diolcagaster claritibia adult measuring ~2mm in length (Photo credit J. Fernandez, AAFC-Ottawa).
Reminder – Researchers need your help – They are looking for LIVE cereal leaf beetle larvae from any field across the Canadian prairies in order to assess Tetrastichus julis parasitism rates.
If larvae are encountered in 2018, please carefully collect 20-30 of them and put them with some cereal leaves and a moist paper towel in a hard container (e.g. plastic yogurt container) with holes poked in the lid for air. Pack the parcel with ice packs, label with your name, date, crop type, and location, and send them to us. Email or phone us for information on how to ship for free.
What’s in it for you? Learn if cereal leaf beetle is being controlled by natural enemies in your field. If you need T. julis, we may be able provide you with some.
Researchers need your help – They are looking for LIVE cereal leaf beetle larvae from any field across the Canadian prairies in order to assess Tetrastichus julis parasitism rates.
If larvae are encountered in 2018, please carefully collect 20-30 of them and put them with some cereal leaves and a moist paper towel in a hard container (e.g. plastic yogurt container) with holes poked in the lid for air. Pack the parcel with ice packs, label with your name, date, crop type, and location, and send them to us. Email or phone us for information on how to ship for free.
What’s in it for you? Learn if cereal leaf beetle is being controlled by natural enemies in your field. If you need T. julis, we may be able provide you with some.
This week’s Insect of the Week is Tetrastichus julis. They are a parasitoid enemy of the cereal leaf beetle. Mature larvae overwinter in infested cereal leaf beetle cocoons and emerge in spring to lay more eggs in cereal leaf beetle larvae. Adults feed on nectar and aphid honeydew.
For more information on Tetrastichus julis, visit our Insect of the Week page.
Tetrastichus julis – adult parasitizing a cereal leaf beetle larva (Swaroop Kher, University of Alberta/AAFC)
Follow @FieldHeroes to find out how natural enemies are working for you for FREE to protect your crops!
This week’s Insect of the Week is the Aphidius parasitoid wasp. Their hosts include over 40 species of aphids. Egg to adult development occurs inside the host. New adults chew a hole in the mummified aphid to exit and immediately search for new aphid hosts.
For more information on the Aphidius parasitoid wasp, see our Insect of the Week page.
Parasitized English grain aphid (Tyler Wist, AAFC)
When encountering insects found in prairie crops, I quite often don’t know if I’ve found a ‘good’ or a ‘bad’ insect. In these instances, I feel like Glinda the Good when she asked Dorothy, ‘are you a good witch, or a bad witch?’ Some are ‘good’ insects (predators, parasitoids, pollinators, decomposers) and others are ‘bad’ (defoliators, sap suckers, seed eaters, root eaters, disease vectors). And of course there’s also the great grey middle where some insects have a balance of good and bad traits, while others are seemingly and completely benign. Many times, you can’t tell simply by their appearance which category an insect falls in (unlike Glinda in identifying a bad witch: ‘Only bad witches are ugly.’). Especially when you encounter their adult form as it’soften the larvae or nymphs that cause most of the damage.
AAFC entomologists
study many aspects of the insects that make their home in our crops and nearby
land. One of those aspects is how the ‘good’ insects contribute to the
producers’ bottom line in terms of the pest control services they provide. Economists estimate that for
every $1 invested in Integrated Pest Management research, the industry gets
back about $15 in benefits.For a brief look at some of the work AAFC
entomologists do in Saskatchewan, make some popcorn, sit back and watch our newvideo.
I would be remiss
if I didn’t add that AAFC entomologists partner with provincial, university, industry
and private entomologists in the region and across Canada to discover, monitor and
publicize the latest findings and trends in crop pests and beneficials.
You might also
like to take a look at ‘Field Crop and Forage Pests and their Natural Enemies
in Western Canada: Identification and Management Guide’ for information and
full colour pictures of important economic Prairie crop insects and spiders. Download
links are available on the ‘Insect of Week’ page.
Last year, the focus of the
Beneficial Insect of the Week was crop pests. This year,
we’re changing things up and highlighting the many natural enemies that
help you out, silently and efficiently killing off crop pests. [note: featured
Insects of the Week in 2015 are available on theInsect of the Week page]
Natural enemies don’t just appear from nowhere – they rely on nearby
non-crop and (semi-)natural sites for shelter, food, overwintering sites and
alternate hosts for when crop pests are either not present or in low numbers.
How you manage these sites can have a huge impact on natural enemies’ capacity
to supress pests when you need them to. These same sites are also essential
habitats for pollinators, important for maximizing yield of non-cereal seed
crops (e.g. oil seed crop). A recent publication, ‘Agricultural practices that
promote crop pest suppression by natural predators’, describes the role of
non-crop areas and management practices to nurture natural enemy populations.
Go to the Insect of the Week page for download links for
this publication. There you will also find more information about natural
enemies, the pests they control and details about important crop and forage
pest insects by downloading the new Field Crop and Forage Pests and their
Natural Enemies in Western Canada – Identification and Management Field Guide.
The importance of non-crop areas as habitat for beneficial insects
Last year, the focus of the
Beneficial Insect of the Week was crop pests. This year,
we’re changing things up and highlighting the many natural enemies that
help you out, silently and efficiently killing off crop pests. [note: featured
Insects of the Week in 2015 are available on theInsect of the Week page]
Natural enemies don’t just appear from nowhere – they rely on nearby
non-crop and (semi-)natural sites for shelter, food, overwintering sites and
alternate hosts for when crop pests are either not present or in low numbers.
How you manage these sites can have a huge impact on natural enemies’ capacity
to supress pests when you need them to. These same sites are also essential
habitats for pollinators, important for maximizing yield of non-cereal seed
crops (e.g. oil seed crop). A recent publication, ‘Agricultural practices that
promote crop pest suppression by natural predators’, describes the role of
non-crop areas and management practices to nurture natural enemy populations.
Go to the Insect of the Week page for download links for
this publication. There you will also find more information about natural
enemies, the pests they control and details about important crop and forage
pest insects by downloading the new Field Crop and Forage Pests and their
Natural Enemies in Western Canada – Identification and Management Field Guide.
Last year, the focus of the BeneficialInsect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on theInsect of the Week page]
Early in the season, cabbage seedpod weevil adults can cause canola flower budblasting as they feed on developing flowers and later in the season, they will feed on pods. However it’s the larvae that cause most of the damage by feeding on developing seeds; infested pods are also more prone to shattering and may have a higher incidence of fungal infections. To the rescue are tiny wasp parasitoids that attack the adults (e.g. Microtonus melanopus) and larvae (e.g. Trichomalus lucidus).
For more information about these natural enemies, other pests they control and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
Trichomalus lucidus, a cabbage seedpod weevil parasitoid.
CC 3.0 BY-NC-SA CNC/BIO Photography Group, Biodiversity Institute of Ontario
If you encounter aphids in canola, know that it could be one of several species! The following was kindly offered by Dr. Julie Soroka (Research Scientist Emeritus with AAFC-Saskatoon):
A small survey was conducted in canola in central Saskatchewan in 2014 and 2015 and a few fields were observed with aphids. When found, over 90% of the aphid colonies were turnip aphid (Lipaphis erysimi). Of the remainder, more of the generalist feeder, the green peach aphid (Myzus persicae), was found than cabbage aphid (Brevicoryne brassicae). Interestingly, several of the aphid colonies were infested with the parasitic wasp, Dieretiella rapae!
Bertha armyworm parasitoids – Ichneumonids and Tachinids
Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] This week’s Insects of the Week are tachinids, and ichneumonidae. The adult tachinid will feed on flower nectar, honeydew from aphids, scales, and mealybugs. The tachinid, Athrycia cinerea (Coq.), is a parasitoid of the Bertha armyworm. Ichneumonidae adults also eat nectar and aphid honeydow, however, its larvae (Banchus flavescens, Cresson) are parasitoids of Lepidoptera, Coleoptera, Diptera, Hymenoptera, and some spiders. For more information about these parasitoids, the other pests they control and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
Cotesia margeniventris (parasitoid) Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] This week’s Insect of the Week is Cotesia marginiventris (sorry, no common name), a braconidid wasp parasitoid. Female C. marginiventris lay their eggs in the larvae of cabbage looper, black cutworm, corn earworm, variegated cutworm, armyworm and fall armyworm.
For more information about C. marginiventris, the pests it controls and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
Cotesia marginiventris parasitoidizing beet armyworm larva.
Photo cc-by-nc Debbie Waters, University of Georgia, Bugwood.org
Tetrastichus julis (parasitoid) Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] This week’s Insect of the Week is Tetrastichus julis (sorry, no common name), an important cereal leaf beetle parasitoid. Where T. julis has become established, it can reduce cereal leaf beetle populations by 40 – 90%, preventing yield loss without using pesticides. See also the factsheet, BiologicalControl at its Best, Using theT. julis Wasp toControl the Cereal Leaf Beetle (French version).
For information about the cereal leaf beetle (p. 24) and other pests and their natural enemies, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
T. julis adult parasitizing a cereal leaf beetle larva
This week’s Insect of the Week is the Aphidius wasp (Aphidius sp.), Most people’s experience with wasps is a painful encounter with a paper wasp, hornet or yellow jacket. However, there are far more beneficial wasps than hurtful. The Aphidius wasp is just one of many such, with female wasps parasitizing up to 350 aphids during their short lifespan. Small but mighty, a large enough population of Aphidius wasps (working alone or together with other cereal aphid predators/parasitoides) can bring down a cereal aphid population to the point where spraying becomes unnecessary. See more information in the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
