Citrus thrips

Systematic position: The citrus thrips (Scirtothrips aurantii) belongs to the order Thysanoptera and the family Thripidae. This tiny, pale-yellow insect is a major agricultural pest known for its high reproductive rate and its status as a significant threat to international fruit trade.

Host plants: It is a polyphagous insect that primarily infests citrus species, including oranges, lemons, and mandarins. Beyond citrus, it causes damage to crops such as tea, mango, avocados, and various ornamental plants, making it a difficult pest to contain in diverse agricultural settings.

Biology and life cycle: The life cycle comprises egg, two larval instars, prepupa, pupa, and adult stages. Females lay eggs inside the epidermal tissues of tender leaves and young fruits. The development from egg to adult is highly temperature-dependent, allowing for multiple overlapping generations in tropical and subtropical regions.

Damage and economic impact: The primary injury is caused by adults and larvae rasping the surface of young plant tissues to feed on cell sap. This leads to characteristic silvery-grey or brownish scabs on fruit, often appearing as a ring around the stem-end. Severe infestations result in stunted shoots, leaf distortion, and significant yield losses in commercial orchards.

Control measures: Management programs typically integrate several tactical approaches:

• Deployment of yellow sticky traps to monitor population density and identify the start of seasonal activity.
• Strategic application of targeted insecticides, such as spinosyns, during the critical window of fruit set.
• Biological control using predatory mites (e.g., Amblyseius species) to reduce pest numbers naturally.
• Cultural practices such as pruning affected branches and removing alternative host plants to disrupt the life cycle.