The tomato leaf miner (Tuta absoluta), a major pest of field- and greenhouse-grown tomatoes, belongs to the family of Gelechiidae. It is oligophagous, feeding mainly on Solanaceae species. The main host is tomato but it also feeds on other solanaceous crop plants including potato, eggplant, capsicum pepper and tobacco as well as weeds such as Datura stramonium, Lycium chilense, and Solanum nigrum.
Life cycle and appearance of Tomato leafminer
The female moth of the tomato leaf miner (Tuta absoluta) lays about 260 eggs. The eggs of the tomato leaf miner (Tuta absoluta) are cylindrical. Their colour varies from creamy white to bright yellow, darkening in the embryonic phase and becoming almost black near eclosion.
The first-instar larvae are whitish to yellowish after emerging. They mine inside the leaf, stem or fruit. In the second to fourth instars they become greenish with a black band behind the head.
The prepupae of the tomato leaf miner (Tuta absoluta) are lighter than the feeding larvae and have a typical pink colouration on the dorsal surface. Caterpillars can temporarily be found outside the leaf mines or fruit.
Pupation takes place in the soil or on the surface of a leaf, in a curled leaf or in a mine. If they leave the mines they build silk cocoons on the leaflets or in the soil. When pupation occurs inside mines or fruits, the prepupae do not build cocoons. Pupae have a greenish coloration at first, and then turn chestnut and dark brown shortly before adult emergence.
Adult moths of the tomato leaf miner (Tuta absoluta) are grey-brown with filiform antennae, alternating light or dark segments and recurved labial palps, that are well developed. Black spots are present on the anterior wings. Adults are nocturnal and usually hide between leaves during the day.
The most distinctive symptoms of damage done by the tomato leaf miner (Tuta absoluta) are the blotch-shaped mines in the leaves. Caterpillars prefer leaves and stems, but they may also occur underneath the crown of the fruit and even inside the fruit itself. On leaves, the larvae only feed on mesophyll tissues, leaving the epidermis intact. Fruits can be attacked as soon as they are formed but the larvae only feed on green fruits. In case of serious infection, leaves die off completely. Mining by the caterpillar causes malformations. Damage to fruit allows fungal diseases to enter, leading to rotting fruit before or after harvest.