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Thrips in Mango

Thrips in Mango

Scirtothrips spp.

insect

In a Nutshell

    Curled, distorted young leavesDefoliationInfested twigs are shortenedSilvery spots on fruits which turn brown as infestation progressesAdults are dark brown (1mm), nymphs creamy yellow

Hosts: %1$s

· Mango

Symptoms

Young leaves are scarred, curled along the midrib, distorted, and may drop prematurely. Twigs of infested shoots are much shorter than uninfected ones. Heavily attacked plants are stunted or dwarfed. Infested fruits show silvery spots that later turn brown. Some of the species of Scirtothrips may also cause lesions on the fruits' peel, reducing their market value. Adult thrips are dark brown to black and just over 1 mm long. Nymphs are cream yellow with two bright red bands around their body. Both nymphs and adults rub and suck sap from the surface of plant tissues and leave silvery or dark rusty stains. Fecal excretions on the surface of infested plants attract sooty mold that may worsen the symptoms. It is considered one of the key pests of mango in south-east Asia.

Trigger

All species of Scirtothrips are polyphagous and can feed on a variety of hosts. Adults usually have a 1 mm long, black body while nymphs (young thrips) are cream yellow with two bright red bands around their body (in some species). Females lay small eggs singly into the tender tissues of inflorescences and fruits or on the surface of young leaves. After hatching pale-white, translucent nymphs feed on the leaves and fruits of mango trees (depending on species). Having reached maturity, they subsequently fall onto the ground where they perform the last stage of their life cycle (pupa) in the soil, or on plant remains. Thrip populations are low in winter and reach their peak in summer. The complete life cycle varies in length depending on environmental conditions, but optimal temperatures range around 26°C, their developmental threshold is at 10°C. Thrips are spread over large distances by wind.

Biological Control

Predatory wasps and mites, flower bugs, and other natural enemies are important control agents of thrips and need to be conserved. Neem based pheromone traps or sprays can control thrips populations. The bio-insecticide Spinosad effectively controls the pest. The pathogenic fungi Fusarium semitectum can be employed to reduce thrips populations.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Insecticide sprays containing fluvalinate or acephate are effective against the pest. Chemicals such as abamectin, azadirachtin, deltamethrin, lambda-cyhalothrin and lufenuron may also be used against thrips.

Preventive Measures

    Select resistant varieties, if availableUse yellow sticky traps to monitor thrip populationsKeep the soil well irrigated and avoid excessive use of nitrogen fertilizersThese promote thrip infestationsEnhance tree tolerance by maintaining decent fertilization and cultural practicesAvoid planting alternative hosts like cashew, grape, guava, avocado and ornamental shade trees nearbyWindbreaks can protect the orchard from long distance infestationsTill the soil to bring thrip pupae to the surface, exposing them to the sunAvoid over-use of insecticides to preserve populations of beneficial insects