Roots 'n' Shoots: Ladybeetle (Ladybug or Ladybird): Biological Control - Garden Critter of the Month

Saturday, 22 February 2014

Ladybeetle (Ladybug or Ladybird): Biological Control - Garden Critter of the Month

Ladybeetles (Ladybugs or Ladybirds) at a glance

Occupation:
Predator or Pest
Value to Gardener:
3/5 - Pest Controller (some are pests!)
Danger to Humans:
1/5 – Harmless
Availability:
5/5 – They’ll arrive or you can buy some


Anatomy of Ladybug
(ladybird, lady beetle)
Coccinellidae

Quick Intro

Ladybugs, ladybirds or ladybeetles; these insects are firm favourites amongst gardeners and non-gardeners alike with the classical image of a red-and-black-spotted beetle coming to mind. Little do most people realise that, yes, most ladybirds are beneficial and gobble up aphids, but many are pests too, devastating crops overnight!

Science Stuff

Ladybeetles have been unfortunately miss-named by the more popular term ‘ladybug’, since they aren’t true bugs (those belonging to the Hemiptera family are bugs; where half of the wing is membranous and the other half is hardened).

Ladybeetles are beetles belonging to the Coleoptera order of insects and have forewings that are completely hardened (elytra). The forewings cover the hind wings, which are fully membranous and used for flight.

Ladybeetle with elytra and hind wings expanded for flight

Ladybeetles belong to the Coccinellidae family of beetles. They have many different combinations of black, yellow, orange, red colours arranged in a myriad of stripes and spots or otherwise pattern-less.


Habitat

Ladybeetles are where their prey items or food plant is. This means that the beneficial ladybug fly in and breed on plants with prey items, whereas pest-species invade agriculturally-important crop stands.

Diet

Most adult ladybeetles and larvae are carnivorous and will munch through armies of aphids, mealy bugs, thrips and similar vegetable pests. Some ladybeetles are generalists, feeding on a wide range of pest insects, whereas other might specialise in a few, see table below.

Beneficial ladybeetles, their names and pests they specialise in destroying.
Common Name
Scientific Name
Pest eaten
Black two-spot ladybeetle
Chilocorus distigma
Red scale of citrus
Black-ringed ladybeetle
Oenopia cinctella
Psyllids, leaf beetle eggs & larvae, black and green aphids
Humbug ladybeetle
Micraspis striata
Small insects (thrips)
Spotted Amber ladybeetle
Hippodamia variegata
Aphid specialist
Chequered ladybeetle
Harmonia vigintiduomaculata
Soft bodied pests (aphids, mealy bugs, scale)
Lunate ladybeetle
Cheilomenes lunata
Aphids
Black mealy bug predator
Exochomus flavipes
Aphids, mealy bugs, soft scale, cochineal insects

The Lunate and Black Mealy Bug Predator ladybeetles are dispersed across South Africa, which means that when you garden is under attack these super-beetles will come to the rescue. The Black Two-Spot and Humbug ladybeetles occurs Northern and Eastern parts of South Africa, whereas the Spotted Amber ladybeetle also occurs along the coast. The Chequered ladybeetle is only found along the eastern coast line and the Black-ringed ladybeetle is found in the Cape regions.

Yellow Shouldered Ladybeetle (Apolinus lividigaster)
 eating milkweed aphid (Aphis nerii)

There is one big consideration you should be aware of when relying on your ladybeetles for pest control: Ladybeetles will only be present when a heavy infestation (thick layers on several plants) of pest species are available. This means no pesticide use, organic or otherwise, so that pest populations can reach large enough numbers to attract ladybeetles. Once the ladybeetles arrive they will make short work of the pests on the plants. So the trade-off would be resisting the urge to wipe out the aphids until the ladybeetles are recruited. I am not sure about the exact amount of aphids our South African species can gobble in a day, but numbers range from 50-300!

I had a lot of ladies in my garden this year (yes, I did not spray once since the beginning of spring, mostly out of laziness, but then I had all these wonderful ladybeetles arrived to assist with my massive aphid infestation). The major infested crop was the Florence fennel, which was part of the insectary, and maintained the ladybeetles headquarters. Other infested plants included the peach, which was subsequently cleared of aphids by the beetles, and the potatoes, mainly at their leaf tops until they finished cropping and died. Once I removed the fennel, (as it was bolting not 'bulbing' in the hot sun, hence all the aphids) after a huge rain storm washed away most of the aphids, all the ladybeetles left for better pickings. Here are some photos of the ladybeetles (larvae, pupae and adults), which you will likely find in Gauteng, Johannesburg, Sandton and the surrounding areas (Roodepoort, West Rand...).


Black Mealy Bug Predator,
Exochomus flavipes

Black ringed ladybeetle'
completely spotless,
Oenopia cinctella
I did mention that the Black-ringed ladybeetle is a Cape inhabitant, but I think it might have been transported to Gauteng, because I had a whole swarm of them, including several morphological variants (morpho. var.). Ladybeetles and their variants are hard to ID, since spots and colours can change drastically! The community at Project Noah helped me out with IDs, so here are the ladybeetles morpho-variants:

Black ringed ladybeetle,
Variation 3: two tiny black spots,
Oenopia cinctella
Black ringed ladybeetle
Variation 2: two hemi-stripes,
Oenopia cinctella
Black ringed ladybeetle
Variation 1: 4 solid stripes,
Oenopia cinctella
Black ringed ladybeetle
Pupae new,
Oenopia cinctella
Black ringed ladybeetle
Pupae old,
Oenopia cinctella

Ladybeetle larvae black and white,
I think these are the black-ringed larvae
They look like little monsters! :)

Lunate ladybeetle,
Cheilomenes lunata
Lunate ladybeetle,
Cheilomenes lunata
This one has newly emerged, hence lighter colour
Lunate ladybeetle pupae (bright orange),
Cheilomenes lunata

Ladybeetle larvae cream
I think these are the Lunate ladybeetle,
Cheilomenes lunata
Nice and fat!

Spotted Amber Ladybug
Hippodamia variegata
Spotted Amber Ladybug
Hippodamia variegata




















I am not sure about this one, only saw it once in my garden
Think that it is a Melanic colouration (dark version) of the
Black ringed or Spotted Amber ladybeetle

Now we get to discuss some of the herbivorous ladybeetles. These ladybeetles lay their eggs on the undersides of leaves, both larvae and adults are herbivorous, quickly skeletonising leaves. Most plants affected are the Cucurbits (squash, pumpkin, watermelon, cucumber) and Solanaceae crops (peppers, tomatoes, potatoes, eggplant, nightshade, Cape gooseberry).

Common Name
Scientific Name
Plants eaten
Cucurbit ladybeetle
Henosepilachna bifasciata
Cucurbits (pumpkin, watermelon, cucumber) and potato
Nightshade ladybeetle
Epilachna paykulli
Solanaceae family (potato, tomato)
Potato ladybeetle
Epilachna dregei
Potato, tomato, peppers, sometimes cucurbits

The Cucurbit and Nightshade ladybeetles are widespread throughout South Africa, so there is no escaping them! The Nightshade ladybeetle is restricted to the Northern and Eastern parts of South Africa.

Ladybeetle eggs
I had a massive infestation of Potato ladybeetles on the potatoes growing in the old pumpkin patch. The best way to deal with them is to pick them off by hand (into a plastic bag) and stomp on them (instant death). Any chemical pesticide that could wipe them out will also harm other ‘higher’ beneficial insects, such as spiders, bees, beetles and mantids. Unfortunately I don’t have an organic alternative, which would likely also harm other beneficials, so the only option is physical removal. Be careful when picking them off as they squirt a yellow liquid onto your hand that is smelly (a defence mechanism, known as reflex bleeding, which is unpleasant for predators to eat).  Otherwise if you could get some spider and mantids into the patch, they’ll likely lighten the infestation by eating a few.

Potato ladybeetle,
Epilachna dregei
Potato ladybeetle infestation on potatoes,
Epilachna dregei
Potato ladybeetle pupae,
Epilachna dregei
These have just pupated, the spikes fall off after a while
I was convinced I had taken pictures of the Potato Ladybeetle larvae, but clearly I was mistaken. They are about half the size of the other larvae, very bright orange and they are full of spikes. When I see one, I'll take a pic and post it here...

Ladybeetle – SOS

Globally we have a problem with our ladybeetles, much as with our amphibians, due to habitat destruction and the introduction of invasive species. The most prominent invasive species are:

Common Name
Scientific Name
Problem status
Multi-coloured Asian ladybeetles (MALB) or Harlequin ladybeetle or Halloween ladybeetle
Harmonia axyridis
World-wide invasion problem. In spring they eat aphids, in winter they feed on fruits leading to spoilage. MALB are sometimes crushed with grapes during wine-making and taint the wine with their reflex bleeding alkaloids.
Mexican Bean Beetle

Epilachna verivestis
Especially problematic in the United States. Herbivore that destroys several legume crops, such as beans, alfalfa, peanut, clover and others (okra, squash , eggplant).


Multi-coloured Asian Ladybeetle,
Harmonia axyridis,
Morphological variants, including melanic colourations 


It seems that exotic ladybeetles have a greater survival capacity than native ones, partly due to egg predation being less on exotics ladybeetles. This means that exotic ladybeetles are under less stress, produce more larvae and have greater overall populations, which out-compete native ladybeetles (Ref 1). Another possibility is that the invasive beetles carry disease-causing organisms unfamiliar to native beetles, which end up becoming infected and die, Ref 2 (much like when Smallpox was brought to America by European explorers and devastated the native Indian populations).

Several movements have been established to conserve and document native ladybeetles, such as The Lost Ladybug Project (North America) which aims to protect native ladybeetles. They also have a ladybeetle identification tool and links to additional projects with the same aim but for other animals. You can also make contributions of your ladybeetle spottings on Project Noah, and The Lost Ladybug Project is also there as Mission 34021.

Official Website


Official Website


Ladybeetles last thoughts…

Ladybeetles are definitely great biological control agents, but you have to wait until pest species multiply to high enough densities in order to have ladybeetles coming into your garden. Additionally, herbivorous species may cause confusion, especially amongst the larvae and pupae spotted in the garden. We all need to do our bit to help preserve our native species, such as the removal of invasive species, reduced pesticide use and help to document native species we see in our gardens.

   





Related Articles

Insectary - Information on establishing a biological control agent attractor (how to attract beneficial insects to your garden) and details on insects that can serve as biological control and the pests they consume.



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4 comments:

  1. Interesting blog, thank-you! You don't perhaps know of a source of lady beatles in South Africa (Pretoria)? I have a small home aquaponics system and have some aphids I'd like taken care of. I know in the US and AUS one can buy lady bugs with courier delivery to help sort out an infestation. Thanks!

    ReplyDelete
  2. Unfortunately I am unaware of ladybug suppliers in South Africa - it seems like a gap here... the only suggestion that I have is trying to get an overseas supplier that can ship you the eggs and then you'll have to hatch them out yourself. The only other option is to get them yourself ... maybe get an infestation of aphids going outside and see if you can attact a few ladybugs, round them up and place them in your system - perhaps you get lucky and they lay eggs as well! Good Luck!

    ReplyDelete
  3. Good evening. Thank you for the amazing info. We started with a small-scale farming in Pretoria. Do you perhaps know of anyone we can buy lady beatles from?

    Thank you so much!

    ReplyDelete
  4. No unfortunately there are no ladybug suppliers in SA as of yet. You best bet would be to attract them yourself - you can always set up a patch of 'sacrificial plants' such as fennel or dill and let them become overrun with aphids. After which the ladybugs will swarm to and lay eggs on. You can always relocate them to where they are needed, but ladybugs have their own ideas of where they would like to be so if it isn't a closed system they won't stay long and fly away. Also they will only be in the vicinity where there is a lot of potential prey (either aphids or mealy bugs) so if you only have a mild infestation they are likely not going to come in large numbers. Therefore a 'ladybug patch' would likely be the best way to get them there and keep them around as long as you maintain a infested plant patch for them so that if their is another milder infestation close by they will end up there as well.

    Let me know if you are planning such a patch and its success!

    On another note - what exactly is your pest problem, because I personally have found that attracting Praying Mantis, Wasps and Spiders as pest controllers a lot easier and a more permanent setup. I have made two wasp houses and both have become occupied by paper wasps who hunt for caterpillars. The spiders get all the fly pests and the hunters eat aphids, leafhoppers and stinkbugs. The praying mantis eat smaller pests when you and move on to larger pest species when large. All lay eggs and remain in the garden throughout the entire year and reach a nice equilibrium in the garden. They are however, non-discriminatory and will prey on other beneficials (such as each other) or pollinators...

    You can see the individual posts for each here:
    Wasps:
    http://rsandss.blogspot.co.za/2013/02/wasps-garden-critter-of-month.html
    http://rsandss.blogspot.co.za/2013/11/house-wasp-diy-beneficial-insect-homes.html

    Spiders: http://rsandss.blogspot.co.za/2014/08/spiders-biological-control-garden.html
    Mantis: http://rsandss.blogspot.com/2012/01/garden-critter-of-month-praying-mantis.html

    Also I would suggest my Insectary post as well where you establish a permanent and undisturbed residence for your biological pest controllers: http://rsandss.blogspot.com/2013/12/insectary-beneficial-insects-garden.html

    Hope that helps! Good luck!

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