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Lycopersicon esculentum (Tomato)

Life > eukaryotes > Archaeoplastida > Chloroplastida > Charophyta > Streptophytina > Plantae (land plants) > Tracheophyta (vascular plants) > Euphyllophyta > Lignophyta (woody plants) > Spermatophyta (seed plants) > Angiospermae (flowering plants) > Eudicotyledons > Core Eudicots > Asterids > Euasterid I > Order: Solanales > Family: Solanaceae

Tomatoes originate in South America and were domesticated in Mexico. They were introduced to Europe by the Spaniards in the 1500's and were initially regarded with grave suspicion because of the reputation of Solanum-like fruit as being poisonous. Even by 1800, people in northern Europe were anti-tomato whereas in Spain it had become the most commonly eaten vegetable.

 

tomato

The 10 or so species of Lycopersicon are native to the western coast of South America from Ecuador to Chile, and the genus also occurs on the Galapagos Islands. They grow in a desert environment with only occasional rain and where dew and fog are the main regular sources of moisture. They can grow as short-lived perennials or as annuals. Vegetable tomatoes were domesticated from the wild Peruvian Cherry Tomato Lycopersicon esculentum var. cerasiforme. So the large tomatoes we usually eat these days were derived from a much smaller cherry tomato. 

It seems that domestication of the Tomato did not take place within its native distribution but in Mexico. It has been suggested that once agricultural fields became established in Mexico, tomato seeds dispersed and defecated by birds were able to become established and it was from these wild tomatoes that Mexicans produced domesticated varieties. It is not known when domestication of tomatoes occurred - by the time the Spanish conquered Mexico in 1523, they were already domesticated. The word 'tomato' is derived from the Spanish 'tomate' which in turn is derived from the Mexican Nahuatl name 'tomatl' which applied both to the tomato as we know it and the husk-tomato (genus Physalis). 

The Tomato was introduced to Europe by the Spaniards in the 1500's and was initially regarded with grave suspicion because of the reputation of Solanum-like fruit as being poisonous. It was also regarded as an aphrodisiac, and was hence called the Love Apple or Pomme d'Amour. It was only by about the late 1700s that tomatoes were being grown and eaten in abundance in Italy and Spain. By 1800 tomatoes had become the most common vegetables in Spain, they were starting to be eaten in France, while in Northern Europe they were still regarded with suspicion. 

There are now a huge array of tomato varieties, many developed from an in depth understanding of their genetics. Characteristics that have been under selection include:

  • fruit size and shape. Size wise, tomatoes range from the large beef tomatoes down to the small cherry varieties. 

  • disease resistance

  • increased yield

  • ease of harvesting by machine. For instance, tomatoes have been developed to stop growing after a certain number of nodes have been produced so that all plants are uniform when harvesting takes place.

  • shortening of stigma to within the anther tube. This has enabled self-pollination thus providing reliable fruit set. Prior to this, when the style extended beyond the anther tube, fruit set was dependant on pollination by insects.  

  • flavour. There was a time not so long ago when flavour was not given much consideration and the varieties were becoming increasingly tasteless but this is changing and some really tasty new varieties are being produced. 

Tomatoes are a prime example of genetically modified crops and while many of the characteristics being incorporated into new varieties are harmless health-wise, we need to be on guard about others that might have long-term insiduous effects we are unaware of.  

Herbivores in southern Africa

Aculops lycopersici (Tomato rust mite)

Arachnida > Acari (mites) > Eriophyidae

A tiny orange-yellow mite measuring about 0.2 mm in length. Their feeding activities (sucking of plant juices) cause the stems of plants to turn bronze or russet in colour and cause superficial cracking. The leaves turn brown or drop off before turning brown. 

 

Tetranychus cinnabarinus (Red spider mite)

Arachnida > Acari (mites) > Tetranychidae (spider mites). 

Sucking of plant juices.

 

Macrosiphum euphorbiae (Potato Aphid)

Insecta (insects) > Hemiptera > Aphididae

Plant suckers [transmit diseases?]

PHYLUM: ARTHROPODA<CLASS:

 

Myzys persicae (Green Peach Aphid)

Insecta (insects) > Hemiptera > Aphididae

Plant suckers [transmit diseases?]

 

Phthorimaea operculella (Potato tuber moth)

Insecta (insects) > Lepidoptera > Noctuidae

Caterpillars eat leaves and stems

 

Agrotis ipsilon (Black Cutworm)

Insecta (insects) > Lepidoptera > Noctuidae

The caterpillars attack young plants at night, cutting them off at ground level.

 

Agrotis longidentifera (Brown Cutworm)

Insecta (insects) > Lepidoptera > Noctuidae

The caterpillars attack young plants at night, cutting them off at ground level.

 

Agrotis segetum (Common Cutworm)

Insecta (insects) > Lepidoptera > Noctuidae

The caterpillars attack young plants at night, cutting them off at ground level.

 

Agrotis subalba (Grey Cutworm)

Insecta (insects) > Lepidoptera > Noctuidae

The caterpillars attack young plants at night, cutting them off at ground level.

 

Chrysodeixis acuta (Tomato Semi-looper)

Insecta (insects) > Lepidoptera > Noctuidae

The first 2 larval instars skeletonise the undersides of leaves. Caterpillars in subsequent instars are highly destructive because they chew holes in fruit but do not enter them. By so doing, they destroy more fruit than they would if they consumed each fruit (as in American Bollworm).

 

Heliothis armigera (American Bollworm)

Insecta (insects) > Lepidoptera > Noctuidae

Caterpillars eat flower buds, flowers and developing fruit.

 

Spodoptera exigua (Lesser Army Worm)

Insecta (insects) > Lepidoptera > Noctuidae

Caterpillars eat the leaves.

 
Coelonia mauritii (Fulvous Hawkmoth)

Insecta (insects) > Lepidoptera > Sphingidae

Caterpillars eat the leaves.

 

Thrips tabaci (Onion thrips)

Insecta (insects) > Thysanoptera

Transmits diseases through its sucking activities.

 

Meloidogyne spp. (eelworms)

Nematoda

 

  References

  • Phillips, R. & Rix, M. 1993. Vegetables. Pan Books, London.

  • Sauer, J.D. 1993. Historical geography of crop plants - a select roster. CRC Press, Boca Raton, Florida.

Text by Hamish Robertson


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