**5. Damage and economic significance**

TLM usually attacks the apical buds, flowers, and new fruits of tomato. Larvae make conspicuous mines and galleries on leaves and stems. Damage can occur at

**81**

**Figure 4.**

*(photos: Antonio Biondi).*

Tuta absoluta *(Meyrick) (Lepidoptera: Gelechiidae): An Invasive Insect Pest Threatening…*

any stage of tomato growth from seedlings to mature plant [8]. The larvae feed on the mesophyll tissue, leaving the epidermis intact, thus creating irregular mines and galleries on the leaves (**Figure 4**). The mines and galleries may become necrotic with time. This mining activities lead to reduction of the photosynthetic potential of infested leaves [1]. Infested tomato with TLM show burnt up-like symptoms [9]. The galleries made by the larvae are wider than that caused by the dipteran leaf miner *Liriomyza trifolii* [9, 22]. Larvae can penetrate the axillary buds of young stems when at high density. Thus, it leads to plant withering and check of vegetative growth [8]. After fruit setting, the larvae excavate tunnels in the fruits, which may facilitate invasion by pathogenic agents, resulting in fruit rot (**Figure 5**). The larvae of TLM have a cryptic behavior and endophagous habit, which makes detection of infestation at an early stage difficult [1]. Damage on stems causes necrosis that reduces tomato plant growth and development. Feeding tunnels and holes in the fruits lower their quality and reduce their market value [1]. The serious damage on tomato, due to *T. absoluta*, is caused by the leaf-mining activities and to a lesser extent by tunneling in the fruits [5]. Damage on tomato can reach 100% if no action is taken against the moth. Estimation of economic losses is difficult due to the interaction of many factors including climate, production pattern (greenhouse versus open field), and production costs including seeds, insecticides, fertilization, and other resources. Most of the damage occurs at the early years of invasion, due to lack of farmers' experience on how to manage the pest [1]. Han et al. [23] and Biondi and Desneux

*DOI: http://dx.doi.org/10.5772/intechopen.93390*

[5] summarized the damage of TLM into the following:

the purchase and application of insecticides

1.Production reduction due to injuries on leaves, stems, and fruits

(IPM) programs and disturbance of natural ecosystems [24].

2.Increase in cost of management practices (IPM) against the pest, particularly

3.The ban or restriction of fresh tomato, from the side of non-invaded countries, which will affect the economy of countries where TLM is an endemic pest

4.Other costs include the disruption of preexisting integrated pest management

*Symptoms of damage appear as mines and galleries on tomato leaves caused by feeding of T. absoluta larvae* 

Tuta absoluta *(Meyrick) (Lepidoptera: Gelechiidae): An Invasive Insect Pest Threatening… DOI: http://dx.doi.org/10.5772/intechopen.93390*

any stage of tomato growth from seedlings to mature plant [8]. The larvae feed on the mesophyll tissue, leaving the epidermis intact, thus creating irregular mines and galleries on the leaves (**Figure 4**). The mines and galleries may become necrotic with time. This mining activities lead to reduction of the photosynthetic potential of infested leaves [1]. Infested tomato with TLM show burnt up-like symptoms [9]. The galleries made by the larvae are wider than that caused by the dipteran leaf miner *Liriomyza trifolii* [9, 22]. Larvae can penetrate the axillary buds of young stems when at high density. Thus, it leads to plant withering and check of vegetative growth [8].

After fruit setting, the larvae excavate tunnels in the fruits, which may facilitate invasion by pathogenic agents, resulting in fruit rot (**Figure 5**). The larvae of TLM have a cryptic behavior and endophagous habit, which makes detection of infestation at an early stage difficult [1]. Damage on stems causes necrosis that reduces tomato plant growth and development. Feeding tunnels and holes in the fruits lower their quality and reduce their market value [1]. The serious damage on tomato, due to *T. absoluta*, is caused by the leaf-mining activities and to a lesser extent by tunneling in the fruits [5]. Damage on tomato can reach 100% if no action is taken against the moth. Estimation of economic losses is difficult due to the interaction of many factors including climate, production pattern (greenhouse versus open field), and production costs including seeds, insecticides, fertilization, and other resources. Most of the damage occurs at the early years of invasion, due to lack of farmers' experience on how to manage the pest [1]. Han et al. [23] and Biondi and Desneux [5] summarized the damage of TLM into the following:


#### **Figure 4.**

*Symptoms of damage appear as mines and galleries on tomato leaves caused by feeding of T. absoluta larvae (photos: Antonio Biondi).*

*Invasive Species - Introduction Pathways, Economic Impact, and Possible Management Options*

may be produced annually. The thermal constant from egg to adult has been estimated to be 453.6 degree days (DD) [19]. TLM larvae do not enter diapause as long as food is available; however, it may overwinter as eggs, pupae, and adults [8, 18].

*The life cycle of tomato leafminer, Tuta absoluta (photos: Antonio Biondi; design: Hamadttu A.F. El-Shafie).*

TLM is an oligophagous feeding on many related species of the family Solanaceae including tomato (*Solanum lycopersicum* L.), potato (*Solanum tuberosum* L.), eggplant (*Solanum melongena* L.), pepper (*Capsicum annuum* L.), sweet pepino (*Solanum muricatum* L.), tobacco (*Nicotiana tabacum* L.), the jimson weed (*Datura stramonium* L.), the African eggplant (*Solanum aethiopicum* L.), and the European black nightshade (*Solanum nigrum* L.) [1, 19, 20]. Sylla et al. [21] reported 12 host plants in the family Solanaceae, 2 in the Amaranthaceae, 2 in the Convolvulaceae, and 1 in the e in native South America, invaded Europe, and Africa. The two hosts in the Amaranthaceae are *Chenopodium album* L. and sugar beet, *Beta vulgaris* L.,

while the Fabaceae is represented by common bean, *Phaseolus vulgaris*.

survive only on small number of host plants [21].

**5. Damage and economic significance**

TLM prefers tomato on which it is considered as a major pest while it is a minor pest on other alternative hosts. Host plant knowledge is essential for developing integrated pest management (IPM) against *T. absoluta* [21]. Sylla et al. [21] studied the oviposition acceptance, oviposition preference, and performance of two population of TLM from France and Senegal on six solanaceous plants, namely, tomato, eggplant, Ethiopian eggplant, potato, sweet pepper, and pepper. Their findings suggest that there is differentiation in the host range of TLM across invaded areas. In this respect, it has been reported that the relation between the female preference (maternity care) and larval performance should be very tight, as the larvae can

TLM usually attacks the apical buds, flowers, and new fruits of tomato. Larvae make conspicuous mines and galleries on leaves and stems. Damage can occur at

**80**

**4. Host range**

**Figure 3.**

**Figure 5.** *Tunnels in ripe tomato fruits excavated by the larvae of Tuta absoluta (photos: Antonio Biondi).*
