Bugs for Growers — Biological control

Now is the right time to use ladybugs to control aphids, mealybugs, mites, scales and thrips- Bugsforgrowers.com

Watch YouTube video about using ladybugs for the control of aphids: "

https://youtu.be/UH9jPIUEheo

 Description: Ladybird beetles are also called as ladybugs and scientifically known as Hypodamia convergens. Both larvae and adults of ladybugs are active predators of many soft bodied insects including aphids, mealy bugs, mites and scale insects. Adult ladybugs are hemispherical shaped and bright orange to red in color with 6 black spots on each wing (Fig. 1) whereas larvae have appearance like an alligator with yellow stripes and reddish dark brown color (Fig. 2).  Since adults of ladybugs are very active predators, they can move very fast after their release and find their prey in the garden. Each adult of ladybug is capable of eating over 5000 aphids whereas each larva in its life-span can eat over 400 aphids (Fig. 3).  Use of ladybugs as biological control agents in the organic gardens is a good choice because released ladybug adults can continuously reproduce and maintain their populations as long as they find their food in the garden.  For example, once ladybugs are released in the garden, they immediately start feeding on their prey.  While feeding they mate and lay up to 1,500 tiny yellow eggs on foliage. Eggs hatch within a week into blackish brown alligator like larvae, which are very mobile. After hatching, these larvae immediately start feeding on the available insect hosts in the garden.  While feeding, larvae molts 3 times before pupation.  The pupae are orange to black in color and attached to any substrate in the garden. Young adults emerge from pupae within 1-2 weeks and life cycle continues.  Ladybugs generally complete several generations in a year and they hibernate as adults during winter. [caption id="attachment_1288" align="aligncenter" width="201" caption="Fig. 1. An adult ladybug"][/caption]   [caption id="attachment_1299" align="aligncenter" width="300" caption="Fig.2. A ladybug larva was feeding on okra aphids"][/caption]   [caption id="attachment_1300" align="aligncenter" width="300" caption="Fig. 3. Red aphids feeding on underside of a tomato leaf"][/caption]  

Ladybugs are effective against following insect pests

• Aphids
• Mealy bugs
• Mites
• Scale insects
• Thrips

How ladybugs are applied in the organic garden?

Ladybugs are commercially available and they sold about 1500 adults in a bag and one such bag is enough to treat about 900 square foot area of garden. After purchasing, if it is possible, release adults immediately at dusk in watered garden near plants infested with aphids or other host insect pests. If it is not possible to release ladybugs immediately after arrival, they can be stored in the refrigerator at 38^o F (4^oC) until you are ready to release them in the garden. However, for their highest survival rate in the refrigerator, it is recommended that the bags containing lady bird beetles should be pre-conditioned upon arrival by rinsing bags under cold water and then transfer them into the refrigerator at 4^oC (38^o F).

Are ladybugs safe to use as biological control agent?

Yes, as they are not harmful to humans, children and pets.

Research Papers: Dreistadt, S.H. and Flint, M.L 1996. Melon aphid (Homoptera: Aphididae) control by inundative convergent lady beetle (Coleoptera: Coccinellidae) release on Chrysanthemum. Environmental Entomology 25:688-697. Eigenbrode, S.D., White, C., Rohde, M. and Simon, C.J. 1998. Behavior and effectiveness of adult Hippodamia convergens (Coleoptera: Coccinellidae) as a predator of Acyrthosiphon pisum (Homoptera: Aphididae) on a Wax Mutant of Pisum sativum. Environmental Entomology 27: 902-909.

Armyworms: The important insect pest of turfgrass foliage

How to identify armyworms?

Armyworms are easy to identify. Adult moths are light reddish brown in color whereas their full grown larvae/caterpillars are brown in color and having several stripes on their body, and a distinctive "Y" shape mark on the head.

• [caption id="attachment_184" align="alignnone" width="293" caption="Adult armyworm moth"][/caption]

[caption id="attachment_217" align="alignnone" width="252" caption="A full grown caterpillar or larva of armyworm"][/caption]

Life cycle of armyworms:

Armyworms develop through four different stages: Moth, egg, caterpillar (larva) and pupa. Adult moths of armyworm begin emerging from over-wintering pupae early June through early August and start mating. After mating, each female moth lays about 500 eggs in a cluster on the lower surface of the leaves. Under optimal environmental conditions, eggs hatch within one week. After hatching from egg, larval stages starts feeding on grass foliage. While feeding, larvae molts (shed its cuticle) five times, and go through six stages (instars) of development. In the late summer mature, larva falls off the leaves and burrow into ground to form pupa, which survive during winter and life cycle continues. 

Damaging stages of armyworms:

• All the six stages/ instars of caterpillars/larvae of armyworms cause damage to grass or other host plants.
• Adult moths do not cause any type of damage to grasses or other plants.

  [caption id="attachment_213" align="alignnone" width="300" caption="Armyworm caterpillars or larvae cause a serious damage to the foliage of several grass species"][/caption]

How damage is caused?

All the larval stages cause damage by chewing margins of leaves of all kinds of grasses during night but hide under thatch during day time. Under sever infestation, caterpillars can skeletonize turf plant and reduce the aesthetic value of turfgrass.

Biological control of armyworms:

• Biological control agents including Nucleopolyhedrovirus, parasitoids (Braconid wasps, Apanteles spp. and Tachinid flies) and entomopathogenic nematodes have a potential to manage armyworms.

Why we should use entomopathoegnic nematodes?

• They can kill armyworm larvae with 48 hours after application.
• They are commercially available and easy to apply.
• They are not harmful to children, dogs, cats, personnel involved in its application and beneficial insects like honeybees.
• They do not need a special permission to apply because they are exempted by EPA.

Which species of entomopathogenic nematodes are effective against Armyworms (see literature below)?

• Steinernema carpocapsae
• Heterorhabdtis indica
• Heterorhabdtis bacteriophora

 What stages of armyworms can be targeted?

All the six stages of caterpillars/ larvae are susceptible to entomopathogenic nematodes. Pupae are also susceptible to entomopathogenic nematodes.

What is a recommended dosage of entomopathogenic nematodes required to control armyworms?

•  For the successful control of most of the soil dwelling insect pests, the optimal rate of 1 billion infective juvenile nematodes in 100 to 260 gallons of water per acre is generally recommended (See Table1).

Where you can buy entomopathogenic nematodes?

• All three entomopathogenic nematodes including Steinernema carpocapsae, Heterorhabdtis bacteriophora and Heterorhabdtis indica are sold in our store.
• Steinernema carpocapsae nematodes available both in liquid (sponge-water suspension) and granulated formulations.
• Heterorhabdtis indica and Heterorhabdtis bacteriophora nematodes available only in liquid (sponge- water suspension) formulations.

How long it takes to deliver nematodes?

We can directly deliver entomopathogenic nematodes at your facility in person (service available only in Athens,Georgia) or by UPS throughout US within 3 days after receiving order.

When to apply nematodes

• To target armyworms caterpillars, entomopathogenic nematodes should be applied starting from late June through late August i.e. when young larval (caterpillars) stages (instars) of armyworms are already hatched from eggs (laid in early June) and started feeding on grass leaves.
• To target especially armyworm pupae (to suppress the armyworm moth emergence in the next spring), entomopathogenic nematodes should be applied in late summer when caterpillars starting to fall off from leaves on the ground for pupation.
• Since nematodes are very sensitive to UV light, they will die within a minute or two when exposed to full sun. Therefore, nematodes should be applied early in the morning or late in the evening to avoid exposure to UV light.
• Another advantage of applying nematodes late in the evening is that armyworm caterpillars can be easily targeted because they are generally active and searching for food during night and easily found by entomopathogenic nematodes like Steinernema carpocapsae that uses sit and wait (ambush) strategy to attack its passing by host.  Since armyworm caterpillars are moving actively during night in search of food, they can easily come across to entomopathogenic nematodes like Heterorhabdits bacteriophora and Heterorhabdits indica that uses cruising strategy to finds its host. Because of cruising strategy, both Heterorhabdits bacteriophora and Heterorhabdits indica nematodes can also find caterpillars that are hiding under thatch during day time.

How entomopathogenic nematodes kill armyworms?

After application of either Steinernema spp. or Heterorhabditis spp. on the lawns, their their infective juveniles find armyworm larva or pupa and enter into its body cavity through natural openings such as mouth, anus and spiracles. Once infective juveniles of both Steinernema spp. and Heterorhabditis spp are in the insect body cavity, they release several cells of symbiotic bacteria, Xenorhabdus spp. and Photorhabdus spp., respectively from their gut via anus in the insect blood. Insect blood is conducive for the multiplication of symbiotic bacteria. In the blood, multiplying nematode-bacterium complex causes septicemia and kill their insect host usually within 48 h after infection.

Literature:

• Andalo, V., Santos, V., Moreira, G.F., Moreira, C., Freire, M. and Moino, A. 2012.   Movement of Heterorhabditis amazonensis and Steinernema arenarium in search of corn fall armyworm larvae in artificial conditions.  Scientia Agricola 69: 226-230.
• Ansari, M.A., Waeyenberge, L. and Moens, M. 2007.  Natural occurrence of Steinernema carpocapsae, Weiser, 1955 (Rhabditida: Steinernematidae) in Belgian turf and its virulence to Spodoptera exigua (Lepidoptera: Noctuidae). Russian Journal of Nematology 15: 21-24.
• Kim, J. and Kim, Y. 2011.  Three metabolites from an entomopathogenic bacterium, Xenorhabdus nematophila, inhibit larval development of Spodoptera exigua (Lepidoptera: Noctuidae) by inhibiting a digestive enzyme, phospholipase A (2). Insect Science 18: 282-288.
• Negrisoli, A.S., Garcia, M.S., Negrisoli, C.R.C.B., Bernardi, D. and da Silva, A. 2010.  Efficacy of entomopathogenic nematodes (Nematoda: Rhabditida) and insecticide mixtures to control Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) in corn crops. Crop Protection 29: 677-683.