Mass multiplication and field release techniques of important predators

1. Chrysoperla sp.

 In India, 65 species of chrysopids belonging to 21 genera are recorded in various crop ecosystems. Chrysoperla carnea is the most common species and is widely used in cotton ecosystems for controlling aphids and other soft-bodied insects.

Morphology and Biology:

• Eggs: Stalked, green, measuring 0.7-2.3 mm, laid singly or in clusters, turn pale whitish and then black before hatching. Egg period: 3-4 days.
• Larva: White on hatching, has 3 instars completed in 8-10 days.
• Pupa: Spins a cocoon; adult emerges in 5-7 days.
• Adult: Mates repeatedly, pre-oviposition period: 3-7 days.
  • Egg-laying starts on the 5th day post-emergence, peaking between 9-23 days.
  • Male longevity: 30-35 days, Female: up to 60 days.
  • Fecundity: 600-800 eggs/female.
  • Sex ratio Male: Female = 1: 0.85.

Mass Production Procedure:

• Adult Feeding: Adults are fed on a protein-rich diet containing yeast, fructose, honey, Proteinex, and water in a 1:1:1:1 ratio.
• Rearing Method:
  • Adults are reared in pneumatic glass troughs or G.I. round troughs (30 cm x 12 cm) wrapped with brown paper sheets for egg laying.
  • 250 adults (60% females) are kept in each trough, covered with a white nylon cloth secured with a rubber band.
  • Egg Collection: Eggs are laid on brown sheets which are removed daily for further hatching.
  • Larval Rearing: Larvae are reared in plastic tubes, injection vials, or large containers.

Field Release:

• Inoculative Release: 10,000 eggs or larvae are released per hectare.
• Conservation Release: Small quantities are periodically released to establish and conserve predator populations in the field.

2. Australian Lady Bird Beetle (Cryptolaemus montrouzieri)

• Origin: Native to Australia, introduced in India in 1898.
• Target Pests: Mealybugs, green shield scale, and other soft-bodied insects on crops like citrus, coffee, grapes, guava, and ornamentals.
• Significance: One of the most successful examples of classical biological control in agricultural history.

Morphology and Biology:

• Eggs: Pale yellowish white, smooth, shiny, oval to cylindrical, laid from late evening to early morning.
  • Incubation period: 5-6 days, viability: 90-100%.
• Grubs: Four larval instars, 20 days larval stage. Feed on all stages of mealybugs. Develop waxy strands for protection. Defensive mechanism: Exudes yellow fluid when disturbed.
• Pupa: Prepupal period: 2-4 days, pupal period: 7-9 days.
• Adult: Male to female ratio = 1:1. Longevity: 50-60 days, Fecundity: 200-220 eggs. Males are distinguishable by brown coloration on the first pair of legs, while all legs are black in females.

Mass Production Procedure:

• Egg Collection: Eggs are collected from mealybug-infested plants.
• Larval Rearing: Larvae are reared on live mealybug colonies or in artificial media.
• Adult Rearing: Adults are maintained in cages with a constant supply of mealybugs for feeding.
• Cages: Transparent plastic containers with parthenium leaf bouquets are used for egg laying.
• Yield: Around 100-125 adults per rearing cycle.

Field Release:

• Inoculative Release: 500 adults/ha are released, coinciding with the start of monsoon showers.
• Augmentative Release: Periodic releases based on pest population density.
• Effectiveness: Beetles spread automatically to adjoining fields, ensuring wider pest control.

3. Weed Predators

Zygogramma bicolorata (Parthenium Beetle)  Used for controlling the invasive weed Parthenium hysterophorus. Feeding Habit: Adults and larvae feed on parthenium leaves.

Morphology and Biology:

• Eggs: Laid singly or in small groups (up to 5) on the underside of leaves. Egg Period: 4-5 days.
• Larva: Feeds on terminal buds, later moves to leaf blades. Larval Period: 10-15 days.
• Pupa: Pupates in soil. Pupal Period: 8-10 days.
• Fecundity: Up to 1,786 eggs/female.

Mass Production Procedure:

• Adult Rearing: 10 pairs of adults are placed on parthenium bouquets in transparent plastic containers.
• Egg Transfer: Egg-laden leaves are placed on small parthenium plants in cages.
• Cages: 45×60×90 cm cages with zinc sheet trays filled with soil for plant growth.
• Yield: 100-125 adults per cage; open field cages yield about 300 adults.

Field Release:

• Inoculative Release: 500 adults/ha at the start of the monsoon season.
• Spread: Beetles naturally spread to neighboring fields, providing effective weed control.

Neochetina sp. (Water Hyacinth Weevil)

• Target Weed: Water hyacinth (Eichhornia crassipes).
• Species Used: Neochetina eichhorniae (chews leaves and petioles). Neochetina bruchi (bores into petioles, causing wilting).

Mass Production Procedure:

• Adults and larvae are reared on water hyacinth plants in large water tanks or field ponds.
• Egg Collection: Eggs are laid on leaves, larvae bore into petioles.
• Field Release: 500 adults/ha at the onset of the rainy season.
• Effectiveness: Reduces plant growth, vigor, and seed production, leading to the collapse of water hyacinth mats.