TOMATO - INSECT – PESTS

TOMATO LEAF MINER

Scientific name: Tuta absoluta
Host range: Its primary host is tomato, but the tomato leaf miner can also feed on other solanaceous species such as potatoes, eggplants, tobacco or the weed black nightshade. It has also been found in beans (Canadian Food Inspection Agency 2019)

Distribution:

Source: https://gd.eppo.int/taxon/GNORAB/distribution

Importance: Indigenous to South America, the tomato leaf miner has become a pest of global importance in less than 20 years. In Europe, it was first identified in Spain in 2006. It prefers a warm climate, so it causes particularly severe damage in the Mediterranean. In colder countries, it cannot survive outside greenhouses. It has also spread to the Middle East, India and Africa.

Symptoms: General symptoms on the fruit and the stem include puncture marks, distortions and the presence of chewed plant material. Larvae mine inside the leaves, leaving discoloured, irregular spots behind. Severely attacked leaves will wilt and die. On affected fruits, exit holes where larvae have emerged are easily spotted. Secondary infections may result in soft rot.

Source: https://stock.adobe.com/

Source: https://stock.adobe.com/

Description of the insect pest: Adults are greyish-brown moths with a length of about 6 mm and a wing span of 10 mm. Freshly hatched larvae are yellow and tiny, about 0.5 mm long. In later stages, larvae turn greenish or pinkish yellow and develop a black stripe behind the head. Pupae are brown, rarely found on the plant itself.

https://harvesso.com/about_tuta_absoluta.html

https://gd.eppo.int/taxon/GNORAB/photos

Life cycle: Adult females may lay more than 200 eggs, usually one by one, on leaves, stems and young fruit. Hatching larvae immediately bore into the leaves, consuming the mesophyll. 3rd or 4th instars leave the mines and attack other leaves, or more often the fruit. When ready to pupate, they leave the mines. Pupae are found outside the mines, in the soil or on cultivation equipment. Total development takes about 40 days. In greenhouses, up to 9 generations may develop in a single year.

Control:

Larvae are hard to target with insecticides as they are within the mines. The species has developed a resistance against almost all insecticides. Available control methods:

• greenhouse sanitation (thorough disinfection between crops)
• pheromone traps and mating disruption
• biological control agents (Macrolophus, Trichogramma, nematodes etc.)

SOUTHERN GREEN STINKBUG

Scientific name: Nezara viridula
Host range: The green stinkbug is a generalist pest, feeding on plants from more than 30 families. Cultivated hosts include cucurbits, cotton, bean, soybean and tomato.
Importance: Originating in Africa, Nezara viridula is now present globally, causing severe damage in the warm parts of Europe, Asia, Africa and the Americas. Global warming favours its spread. In Europe, it was first discovered in 1998 in Italy.
Symptoms: Adults and larvae may feed on any part of the plant, but they prefer young, vigorously growing shoots, flowers, fruit and seeds. On the fruit, they cause discoloration upon ripening and the development of corky patches below the surface. The area around sucking wounds turns brown and may be attacked by fungi resulting in secondary infections (rots). The faeces and the produce of stink glands contaminate the fruit and cause an unpleasant smell. The saliva injected into the fruit significantly reduces its quality
Description of the insect pest: Adults are typical shield bugs of a length of about 1 cm. They have a uniform bright green colour with 3-5 characteristic white spots along the front edge of the scutellum and two dark marks at its corners. The front part of their body may have a cream-coloured hue in some individuals. Wingless larval instars may take any colour between green and black but later stages always have rows of white or yellow abdominal spots, often with additional small white spots.

Source: project number: HU/02/B/F/PP-136012

Source: project number: HU/02/B/F/PP-136012

Life cycle: Under warm conditions, the bug has 4 generations. The diapause of adults starts at 1°C. They overwinter in cracks and crevices, often in human dwellings. After the winter, they appear in March or April. The bugs are very mobile and actively search for food. Females lay 30-130 eggs in batches on the underside of the leaves. It has 5 larval stages. Total development from egg to adults lasts about 100 days.

Control:

• crop rotation
• minimize weeds inside and in the periphery of the field
• use trap crops around the field to be treated with insecticides (legumes and cruciferous plants)
• chemical control
• biological control (egg parasitoids)

RED TOMATO SPIDER MITE

Scientific name: Tetranychus evansi

Host range: Though the species is polyphagous, it primarily feeds on solanaceous plants, with preferred weed host black nightshade.

Importance: The tomato red spider mite is a destructive invasive pest of solanaceous crops worldwide, originating from South America. With a preference for warm climates and an inability to have a diapause, in Europe it invades fields in the Mediterranean region. In northern parts, it is a greenhouse pest. The four solanaceous crops most threatened by the mite species are eggplant, tomato, potato and tobacco.

Distribution

Source: https://gd.eppo.int/taxon/TETREV/distribution

Symptoms: Being tiny, the mites themselves are hard to spot in the beginning. They feed on both sides of the leaves, tend to concentrate along the veins on the underside. The saliva injected into plant tissues causes shiny yellow lesions on the leaves. Eventually the leaves turn brown and die. When present in sufficient numbers, the mites may kill the entire plant. In the case of severe outbreaks, the web made by the mites is clearly visible.

Source: https://gd.eppo.int/taxon/TETREV/photos

Description of the insect pest:
Eggs are round, 0.1 mm diameter, orange to white in the beginning. The first larval stage has six legs. After moulding, larvae turn orange or red with eight legs. Adult females are about 0.5 mm, oval, orange-red, darker at the side. Males are about 0.3 mm long and rather yellowish. The lack of the two spots on the back tells them apart from the two-spotted spider mite. Females may lay as many as 200 eggs

Life cycle: The tomato red spider mite reproduces continuously (it has no diapause), though females lay less eggs in the winter season. It cannot survive under 12 °C. Under optimum conditions (hot and dry), adults develop within 6 days of hatching. Such short developmental times result in severe outbreaks. Parthenogenesis may also occur, where unfertilized eggs develop into males. When the population grows extremely large, mites will climb to the top of the plants and be carried away by wind, drought or staff (clothing, tools etc.)

Source: https://gd.eppo.int/taxon/TETREV/photos

Control:

• eliminate host weeds (nightshade and other solanaceous plants) from the area, with special regard to the nurseries
• crop rotation
• use healthy transplants
• in small stands, keeping the leaves moist will keep population levels low
• chemical control (acaricides)

THRIPS

Scientific name: Frankliniella occidentalis Pergande; and other species (e.g.Thrips tabaci Lindeman)
Host range: Host range of F. occidentalis is very broad: many ornamentals, vegetable and weed species.
Occurrence and importance:F. occidentalis is widespread in glasshouses. Its importance lies in the fact that it transmits Tomato spotted wilt virus (TSWV). It is listed as a quarantine pest by EPPO.
Distribution:

Source: project number: HU/02/B/F/PP-136012

Source: project number: HU/02/B/F/PP-136012

COTTON BOLLWORM

Source: project number: HU/02/B/F/PP-136012

Source : https://gd.eppo.int/taxon/HELIAR/photos

Life cycle: The cotton bollworm migrates from the Mediterranean area to the northern regions. Females prefer corn and vegetable for laying eggs, the moth has been reported to have 2-3 generations / year (1st May - June, 2nd June August, 3rd until frost). Overwinters like a puppet in the soil.

Control:

• destroy reservoir plants (weeds),
• insecticides against young caterpillars.
• insecticides that inhibit development (e.g. Dimilin)
• For organic control Nemastar®, Steinernema carpocapsae nematode may be applied.

GREENHOUSE WHITEFLY, SILVERLEAF WHITEFLY

Scientific name: Trialeurodes vaporariorum, Bemisia tabaci

Host range: These generalist whiteflies have a very broad host range covering more than a hundred plant families. They cause economically significant damage in e.g. cucurbits, legumes, solanaceous plants and ornamentals.

Importance: The greenhouse whitefly is not native to Europe, but has successfully established in all the European countries, causing severe damage in protected cultivation year-round. The origin of the silverleaf whitefly is still debated, but it occurs everywhere in Europe and is an equally important pest of greenhouse crops. Greenhouse whiteflies and silverleaf whiteflies are also responsible for the spreading Tomato chlorosis virus (ToCV) and Tomato yellow leaf curl virus (TYLCV), respectively. In warmer European countries, they are also prevalent in field cultivations.

Distribution:

https://gd.eppo.int/taxon/BEMITA/distribution

Source: https://gd.eppo.int/taxon/TRIAVA/distribution

TWO-SPOTTED SPIDER MITE

Scientific name: Tetranychus urticae Koch
Host range: The two-spotted spider mite is an extremely polyphagous pest feeding on ornamentals, hop, vegetables etc.
Importance: The two-spotted spider mite is a very important pest of tomatoes grown in protected cultivation. It may also infest field crops, but under the prevalent weather conditions, it rarely causes substantial losses. 
Symptoms: The first symptoms develop in the form of small (1 mm or less), angular, yellow spots on leaves. Heavily infested leaves turn yellow and get necrotic. Plant parts may be covered by a very thin cobweb which protects the mites. Severely infested plants are stunted and their flowers will drop.
Description of the insect pest: Spider mites are very small (0.4 – 0.6 mm long), yellow, green or reddish, of ovoid shape, with two or four dark spots on their back. Newly hatched larvae have 3 pairs of legs. Nymphs have four pairs of orange legs and six rows of cilia on their back. Their eggs are very small, spherical, straw coloured, and shiny. Both adults and immatures have rasping and sucking mouthparts.

Source: https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.53366#sec-2

COLORADO POTATO BEETLE

Scientific name:  Leptinotarsa decemlineata 
Host range: Potato, sometimes tomato
Distribution:

https://gd.eppo.int/taxon/LPTNDE/distribution

Importance: This dangerous pest has been present in all continental areas of the EU for many years and is constantly spreading eastwards. The plants lose significant proportions of their foliage as a result of the feeding of the pest.
Symptoms: Adults and larvae chew large, irregular holes. The damage is extremely serious as all the leaves and small shoots are eaten, leaving only the petioles and possibly the lower part of the main veins. The Colorado potato beetle only feeds on the above ground parts of the plant. The plant may develop new foliage, but at a cost of hindered fruit development and maturation. Yield loss is significant.

https://gd.eppo.int/taxon/LPTNDE/distribution

https://gd.eppo.int/taxon/LPTNDE/photos

Organic oil:

• plant association
• soil covering
• Novodor FC
  neem oil
• crop rotation
• spraying with soapy water
• Nematop, Heterohabditis bacteriophora
• Dipel DF, Bacillus thuriengiensis ssp. kurstaki ABTS-351
• NOVODOR FC, Bacillus thurenginesis var. tenerobrionis

ROOT-KNOT NEMATODES

Scientific name: Meloidogyne hapla and also other species (M. incognita, M. arenaria, M. javanica etc.) in warm regions
Host range: The host range of all Meloidogyne species is very broad and includes a lot of cultivated plants (especially root vegetables), ornamentals and weeds.
Importance: Meloidogyne hapla only occurs on sandy soils in some areas where tomato is cultivated in private gardens.
Symptoms: Infected plants are usually stunted, weak and pale. Young plants may even die. Characteristic galls (root-knots) develop on the roots. These symptoms are quite specific.
Description of the pest: Nematodes from the genus Meloidogyne are very small, not visible to the naked eye. In root knots, females may be seen under the microscope as small, pear-shaped gelatinous objects. The layman will not be able to detect males and invasive larvae in soil samples.
Life cycle: The eggs of Meloidogyne hapla overwinter in the soil. Invasive larvae hatch relatively early (April) as soil temperature increases. They infest roots and induce the formation of galls. Females lay their eggs in gelatinous bags and then die. Males are probably not needed for reproduction as most species of Meloidogyne are parthenogenetic. It is not yet quite clear how many generations are able to develop during a year.

Control:

• crop rotation (non-host plants like cereals should be included),
• varieties highly resistant to Meloidogyne are available.

POTATO CYST NEMATODE

Scientific name: Globodera rostochiensis
Host range: The host range of the potato cyst nematode is rather narrow and includes potato, tomato, eggplant and some solanaceous weeds.
Importance: Globodera rostochiensis occurs frequently on potato fields.
EPPO A1 and A2 Lists of pests recommended for regulation as quarantine pests (EPPO 2022)
Symptoms: In tomato, there are not any clear symptoms of infection, with the exception of presence of small white to brown cysts on roots.
Description of the pest: Nematodes from the genus Globodera are very small, usually not visible to the naked eye. The only stage when the pest is distinguished relatively easily is the is cyst on a root. Cysts are white, later turn brown and about 0.5 mm in diameter.
Life cycle: Cysts of Globodera rostochiensis can survive for several years in anabiosis in the soil. The root exudates of potential hosts make the larvae to hatch. They infects roots and after two juvenile stages they develop into male or female adults. Females are fertilized by males and eggs develop inside their bodies that will finally form the cysts.
Control: 

• crop rotation (if possible, avoid potato and tomato in the same crop rotation),
• prevention of field contamination (certified potato seed), avoid transport of contaminated soil to other fields by machinery etc.
• fumigation of soil is usually too expensive, try to find uncontaminated fields.