Insect Pests of Vegetable, Ornamental and Spice Crops (2+1)

Chrysanthemum aphid and Serpentine leaf miner

1. Chrysanthemum aphid, Macrosiphoniella sanborni (Aphididae: Hemiptera)

• Distribution: Through out the world
• Host: Chrysanthemum

Damage:

• Nymphs and adults by suck the cell sap from growing shoots and apical leaves
• Feeding results in the loss of vigour, yellowing of leaves, premature leaf fall and stunted growth of plants
• Flowers dry up prematurely
• Aphids excrete honey dew on which sooty mould develops and interferes with the photosynthesis.
• This pest is also responsible for transmitting viral disease

Identification:

• Nymphs are greenish black where as adults are chocolate brown which feed in groups
• Adult aphids can be winged or wingless.

Life cycle:

• Alates appear with the environment changes (day length, temperature, etc), when aphid become over crowded or the plants begins to deteriorate and they need migration.
• Reproduction is both parthenogenetic vivipary as well as sexual.

Management

• Spray dimethoate (0.03%) or oxy- demeton methyl (0.025%) as soon as the attack is noticed.
• Repeat the spray after 10 days if required.
• Parasitoids like Aphidius sp and predators such as coccinellids, syrphids and chrysopids are also active against these aphids in the nature.
• When these natural enemies are active, application of insecticides should be avoided.

2. Serpentine leaf miner, Liriomyza trifolii (Agromyzidae: Diptera)

• Distribution: cosmopolitan
• Hosts: Polyphagous

Damage:

• Larvae feed on the palisade mesophyll tissue in between the two epidermis of the leaf.
• Affected leaves give transparent papery appearance in the mined area
• Photosynthesis is reduced.
• Females puncture the leaf for egg laying and feeding
• The attack appears during April and is more pronounced from June onwards.

Identification (Also see under insect pests of tomato)

• Newly laid eggs are white and translucent and turn opaque as the development advances.
• The larvae are orange yellow without legs
• Pupae are orange yellow initially which turns dark brown on maturity.
• The adults are minute grayish black flies with plum red eyes and a yellow spot on the scutellum.
• The females are bigger than males.

Life cycle:

• Larval development is in 10-14 days
• Three larval instars.
• Pupal period is 8-10 days.
• Pre-oviposition, oviposition and post-oviposition periods varies from 1-3, 8-15 and 1-3 days, respectively.
• Male longevity is 8-12 days
• Female longevity is 13-17 days.
• Each female can lay 22-186 eggs

Management

• Natural enemies also suppress this pest
• Parasitoids are more during July-August.
• If attack is more, spray triazophos (0.15%) followed by another spray of deltamethrin (0.0028%) at 10 days intervals.