Insect of the Week (Aug 6) - Doppelgangers – good vs. good (ladybeetle larva vs. lacewing larva)

Often life choices involve lesser evils. But in the case of lady beetle larva and lacewing larva, they both contribute to the greater good. But which one do you have? Both are voracious aphid, mite, mealy bug, insect egg and other soft bodied insect hunters. In fact, lady beetle larva can consume hundreds of aphids during their development. Lacewing larva are no slouch in that department either. Another name for them is aphidlion and they can consume up to 200 aphids per week.

Green lacewing larva
cc by 3.0 Whitney Cranshaw

Ladybird beetle larva
cc by 3.0 Frank Peairs

While both have the same general tapered alligator body, there are few main characteristics that will help to tell them apart.

For more information about these species and more tips on telling them apart, see our Insect of the Week page).

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.

Review previously featured insects by visiting the Insect of the Week page.

Ladybird beetles (Aug 16, 2018; Wk 15)

Reminder - While scouting, you may encounter these fascinating organisms.....

Figure 1. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)

Figure 2. Ladybird beetle pupa (Left) and larva (Right) (photo credit: AAFC-Beaverlodge)

Figure 3. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge)

Figure 4. Ladybird beetle (Coccinella septempunctata) (photo credit: AAFC-Beaverlodge)

Figure 5. Aphids nestled on wheat head (photo credit: AAFC-Beaverlodge)

Figure 6. An aphid "mummy" adhered to a wheat awn.  Mummy is the aphid host converted to
enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge)

Ladybird beetle larvae (Fig. 1-2), pupae (Fig. 2-3), and adults (Fig. 4) can all be found in fields at this time of year.  Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes!  Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids (Fig. 5).  

Ladybird beetles (Aug 02, 2018; Wk 13)

While scouting, you may encounter these fascinating organisms.....

Figure 1. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)

Figure 2. Ladybird beetle pupa (Left) and larva (Right) (photo credit: AAFC-Beaverlodge)

Figure 3. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge)

Figure 4. Ladybird beetle (Coccinella septempunctata) (photo credit: AAFC-Beaverlodge)

Figure 5. Aphids nestled on wheat head (photo credit: AAFC-Beaverlodge)

Figure 6. An aphid "mummy" adhered to a wheat awn.  Mummy is the aphid host converted to
enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge)

Ladybird beetle larvae (Fig. 1-2), pupae (Fig. 2-3), and adults (Fig. 4) can all be found in fields at this time of year.  Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes!  Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids (Fig. 5).  

Insect of the Week (July 09, 2018) - Natural enemies of pea aphids

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.



The many faces of the adult harlequin ladybeetle 
 (aka multicoloured Asian ladybeetle) (Photo: ©Entomart)



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.