**3. Biology and bionomics**

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

common English names in the literature. These are the South American tomato pinworm, the South American tomato leaf miner, the South American tomato moth, the tomato pinworm, the tomato borer, and the tomato leaf miner. For consistency, the tomato leaf miner (TLM) will be used throughout this chapter. The TLM has been considered as a key pest of tomato, in recent years, causing a reduction in tomato yield that can reach 100% if no management action is taken [1]. Increasing of global trade of tomato in the absence of strict quarantine measures and proper surveillance in many tomato-producing countries are the reason behind the vast spread of this pest.

Due to the significance of TLM, the Journal of Pest Science has recently published a special issue on this pest, which was edited by Biondi and Desneux [5]. The special issue gave more consolidated and updated information on the moth biology, population dynamics, chemical and trophic ecology, and novel control technologies. This chapter gives concise information on *T. absoluta* biology and bionomics, economic significance, geographical distribution, invasive potential, natural

*T. absoluta* originated in the Peruvian Central highlands from where it spread to other areas of Peru and then to the rest of Latin American countries during the 1960s [3]. TLM is small moth with body length of 5–7 mm and wingspan of 10–14 mm [8]. The moth has silvery-gray scales and black spots on the forewings. The antennae are long, filiform with black and brown scales (**Figure 1**). Shashank et al. [9] described the male and female genitalia as well as the pupal genital aperture as useful distinguishing character for sexing of the moth. Egg is small (0.36 mm long and 0.22 mm wide) with elliptical shape and creamy white to bright yellow color. Larva is whitish in first instar (0.9 mm long) and becomes greenish or light pink in the second and fourth instar (7.5 mm). Pupa is obtect with greenish coloration at first, turning to chestnut brown and dark brown near adult emergence [8] (**Figure 2**). Tabuloc et al. [10] studies the genome of *T. absoluta* to generate and design a panel of 21 SNP markers for the species identification instead of depending only on morphological identification and symptoms of damage on the host plants. *Tuta absoluta* was originally described as *Phthorimaea absoluta* (Meyrick, 1917) in Peruvian Andes. The genus was changed to *Gnorimoschema* [11] and then to Scrobipalpula [12] and Scrobipalpuloides [13]. Povolny [14] corrected the currently

enemies, and available management options.

**2. Origin, morphology, and taxonomic position**

*Adult moth of tomato leafminer, Tuta absoluta (photo: Antonio Biondi).*

**78**

**Figure 1.**

The TLM has a complete metamorphosis type of reproduction, where it undergoes through four developmental stages, namely, egg, larva, pupa, and adult (**Figure 3**). Adults are nocturnal and hide between host leaves during the day. The female starts to release a sex pheromone 1–2 days after emergence to lure males for mating. The female sex pheromone is a mixture of tetradecatrienyl acetate and tetradecadienyl acetate in a ratio of 10:1, respectively [15, 16]. TLM is known to have multiple mating and the average number of mating per female is about 10.4. Both sexes are polygamous with no refractory period. The female sometimes can exhibit deuterotoky parthenogenesis, which gives both females and males from unfertilized eggs [17]. Males use female sex pheromone to locate females and mating can last from few minutes to 6 hours. Female uses plant volatiles (kairomones) and leaf contact for oviposition. A single female can lay as many as 260 eggs during its life cycle, which may extend to 3 months [18]. About 92% of the total eggs are laid in the 1–3 days following mating [8]. Eggs are laid singly on the upper part of the plant (young leaves, stems, and sepals). The eggs hatch in 5–7 days depending on temperature and relative humidity. After hatching, the larvae go through four instars, which are completed in about 20 days. The mature larva then gets rid of all gut materials, constructs a silken cocoon, and turns into pre-pupa and pupa. Pupation may last for 10–11 days before adult emergence for female and male, respectively. Mature larvae leave the mines and build silken cocoon on the leaflet or in the soil. When pupation occurs in the mines or tomato fruit, the pre-pupa does not build cocoon. Adult longevity may extend for 30–40 days [8]. The whole life cycle of the moth is completed in 29–38 days, depending on the environmental conditions (**Figure 3**). Moreover, about 10–12 generation

**Figure 3.** *The life cycle of tomato leafminer, Tuta absoluta (photos: Antonio Biondi; design: Hamadttu A.F. El-Shafie).*

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].

## **4. Host range**

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*.

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