**8. Conclusions**

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

respectively, their predation and parasitism by the natural enemies seem to be difficult. Nevertheless, numerous natural enemies can still be used in the management of this notorious pest. The eggs seem to be more vulnerable to predations and parasitism because they are exposed on the surface of tomato growing points. However, the efficacy of natural enemies in suppressing *T. absoluta* populations may be altered by environmental abiotic factors through bottom-up effects triggered by agronomic practices such as irrigation and fertilization. Moreover, plant constitutive and/or induced resistance traits against *T. absoluta* are another source of bottom-up effects, which may interact with irrigation and fertilization and jointly affect the performance and population density of *T. absoluta*, and counterpart natural enemies and their interactions [37]. In addition to the arthropod biocontrol agents, microbial biocontrol agents such as entomopathogenic nematode (EPN) of the genera *Steinernema* and *Heterohabditis* have potential to kill larvae of TLM when they are outside their mines.

Recently, the transcriptome data showed that most of the core genes of RNAi pathway such as Dicer-like and Argonaute and putative orthologous Sid-1 genes are present in *T. absoluta*, suggesting the feasibility of RNAi for controlling this pest [50]. Full plant protection and high larval mortality of *T. absoluta* have not been achieved, probably due to a low expression of dsRNA in transgenic plants [51]. Novel management technologies for TPW include genetically modified crops (GM), for example, GM *Bacillus thuringiensis* (Bt) tomato [52]. RNA interference (RNAi) is a biological mechanism that leads to posttranscriptional gene silencing directed by the presence of double-stranded RNA (dsRNA) molecules [53]. Biotechnically, sterile insect technique (SIT) may also be used for the management of TLM [37]. However, this technique may be compromised if field populations of *T. absoluta* can reproduce by deuterotokous parthenogenesis [17]. It is worth to mention here that these authors reported tychoparthenogensis reproduction of *T. absoluta* under laboratory conditions. They stated that the origin of this type of reproduction could be considered as classical automictic tychoparthenogensis or due to the microbial manipulation by bacterial endosymbiont such as *Wolbachia*, which has recently

Chemical control of the invasive TLM is difficult; however, its arrival to new invaded areas has been linked to an excessive application of broad-spectrum insecticides [1, 6, 55], in attempts to curb the outbreaks of the pest and to reduce yield losses in tomato crop. Currently, insecticides application seems to be the most commonly used strategy against *T. absoluta* worldwide in open fields of tomato [1, 56–58]. The cryptic behavior and the endophagous habit of larvae make it extremely difficult to control TLM with insecticides [1, 19]. The possible reasons for difficulty of controlling TLM with insecticides, according to Biondi et al. [1] and Guedes et al.

1.Infestation of tomato by the moth occurs at an early stage of plant growth

2.The multiple attacks by the pest on different plant parts (stems, leaves, buds,

3.The morphology and architecture of tomato plant that provide protection for

**7.4 Biotechnological control**

been identified in *T. absoluta* [54].

**7.5 Chemical control**

[58] include the following:

young fruit, and ripe fruit)

feeding larvae against insecticides

**86**

Recently, tomato leaf miner has emerged as a highly invasive key pest threatening the global production of tomato. The global commercialization and trade of fresh tomato fruit and transplanting material have accelerated the spread of the pest. The impact of *T. absoluta* on global tomato production industries and on the livelihood of small tomato farming communities in Africa and Asia might be more severe in the coming years, unless great efforts are made to contain its spread. Chemical control of *T. absoluta* with insecticides seems to be ineffective and not sustainable; therefore, alternative management options such as biological control and semiochemically based control should be encouraged. The socioeconomic impact of this moth on subsistent agriculture need to be addressed in future studies.

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