The tomato leafminer, Tuta absoluta, is a destructive pest that seriously jeopardises the world’s tomato crop. Alternatives that are environmentally benign and sustainable are essential since traditional pesticide-based control methods raise questions about their effects on environment and the emergence of insect resistance. This paper offers a thorough examination of biological control strategies for controlling T. Absoluta populations while preserving the viability of agriculture. The study focuses on parasitoids, bacteria, nematodes and fungus as main biological control agents. The parasitoids, Trichogramma species and Braconidae family have shown strong capability for lowering T. Absoluta numbers. In particular, Bacillus thuringiensis has shown outstanding performance as biopesticide for controlling the pest. Nematodes, especially Steinernema feltiae and Heterorhabditis bacteriophora and several fungi, such as Beauveria bassiana and Metarhizium anisopliae, have demonstrated their potential to control the pest using eco-friendly strategies. In order to manage T. Absoluta in a long-term and sustainable manner, it is essential to use integrated pest management (IPM) techniques that include these agents. The impact of the pest can be efficiently decreased by combining these treatments with other techniques such as trap crops, pheromone traps and cultural practises. These all-encompassing methods not only reduce the need for chemical pesticides but also encourage the preservation of natural enemies and ecological balance. To maximise their use, enhance their application methods and determine their compatibility with other management practises, the review emphasises the significance of ongoing research. Their effectiveness can be increased even further by being aware of how these agents interact with T. Absoluta and their mechanism of action.
Introduction to Tuta absoluta:
Tomato plants (Solanum lycopersicum L.) are very susceptible to the highly destructive Tuta absoluta (Meyrick), a pest that originated in South America but has since spread widely over the world. The pest poses a significant threat to tomato output due to its extensive host range and capacity to reproduce multiple times each year. The tomato plant’s leaves, stems, and fruits are consumed by the larvae of Tuta absoluta, which results in severe damage and yield losses of up to 100%. The insect has also demonstrated resistance to chemical pesticides, which has prompted the investigation of alternate management techniques.
The management of Tuta absoluta is the main topic of this review study, which focuses on the function of fungal entomopathogens and natural enemies. A review of the pest’s characteristics, including its global distribution, host plants, and chemical characteristics of host plants that draw the bug and its natural foes, comes first. The review study then goes over the many preventative techniques employed to manage Tuta absoluta, including cultural, chemical, and biological tactics. A detailed table/list of all documented predators, parasitoids, parasites, and microbiological agents known to be efficient in controlling Tuta absoluta populations is provided in the publication.
Additionally, a thorough description of the way in which fungal entomopathogens affect Tuta absoluta is provided. The various ways that fungal entomopathogens, such as host penetration, enzyme secretion, and toxin generation, work to suppress the pest are outlined in this paper.
Overall, this review study emphasises the necessity for sustainable and successful management measures for this destructive pest and emphasises the significance of fungal entomopathogens and natural enemies in the management of Tuta absoluta.
Global distribution:
Tuta absoluta is a serious pest of tomato crops and is endemic to South America. It has recently expanded to other continents, including as Europe, Asia, Africa, and Oceania. the pest was initially discovered in Spain in 2006 and has since spread to several other European nations, including Italy, France, Greece, and Portugal. Several African nations, including Egypt, Morocco, and South Africa, as well as regions of Asia, including India, Iran, and Pakistan, have also reported it. Tuta absoluta was discovered for the first time in Australia in 2013 and has since been reported in New Zealand.
Numerous causes, such as the globalisation of trade, the movement of infected plant material, and favourable climatic circumstances in some areas, have made it easier for Tuta absoluta to spread to new areas. The insect, which can produce multiple generations each year, can seriously harm tomato crops and inflict large economic losses. With different degrees of success, management efforts for Tuta absoluta have centred on a combination of cultural, chemical, and biological control approaches. A full understanding of the pest’s biology and ecology is necessary for effective management, as is an integrated approach to control that takes into consideration the different aspects that contribute to the pest’s spread and effects.
Losses by insects:
Tuta absoluta is regarded as a severe pest of tomato crops and is responsible for large losses in tomato output across the globe. This pest is thought to cost the world 700 million dollars every year. It has been documented that the pest can reduce tomato crop yields by up to 100% in South America, where it is thought to have first appeared. T. absoluta was discovered in Spain for the first time in 2006, and by 2008, it had already resulted in 50% losses in some tomato crops. Similar losses of up to 80% in tomato crop production were experienced in Tunisia during the pest’s first year of invasion in 2008.
Since its initial discovery in 2009, T. absoluta has grown to be a significant pest of tomato crops in Egypt, resulting in output losses of up to 70%. The pest was originally discovered in Nigeria in 2015, and since then, it has significantly harmed tomato production, with some regions reporting yield losses of up to 100%. Similar to this, T. absoluta has been linked to yield losses in tomato crops of up to 90% in India (Rathee and Dalal, 2018). T. absoluta has become a huge global danger to tomato production overall, resulting in significant financial losses and compromising food security in many areas.
Host plant:
Plants that support Tuta absoluta include a variety of Solanaceae family members, including tomato, potato, aubergine, and pepper. Sweet potato, tobacco, and groundcherry (Physalis spp.) are some other plants outside the Solanaceae family that have been identified as hosts. The T. absoluta larvae eat on a variety of plant parts, including leaves, flowers, fruits, and stems, seriously harming the crops.
The chemical characteristics of the host plant influence how susceptible it is to T. absoluta infection. For instance, T. absoluta infestation rates have been linked to tomato plant concentrations of total soluble solids (TSS) and total free amino acids (TFAA). Similar findings have been made regarding the attraction of T. absoluta to some volatile substances released by tomato plants, such as (Z)-3-hexenyl acetate and 2-methylbutanal. On the other hand, several chemical constituents of host plants, such as -caryophyllene in tomato plants, have been found to resist or deter T. absoluta.
The natural enemies of T. absoluta, such as parasitoids and carnivores, can be attracted by the chemical characteristics of the host plants. For instance, it has been discovered that particular volatiles released by tomato plants attract natural enemies like the parasitic Necremnus tutae and the predatory bug Macrolophus pygmaeus. Additionally, it has been shown that specific chemical constituents in host plants, such as iridoid glycosides in tomato plants, contribute to plant resistance to herbivores like T. absoluta.
Chemical properties of host plants or chemical compounds, which attract Tuta absoluta insect:
Tuta absoluta is drawn to specific chemicals that its host plants’ emit. Some of these substances have been discovered and researched, such as: Solanum lycopersicum: T. absoluta is drawn to a mixture of volatile organic compounds (VOCs) that the tomato plant emits, including 2-carene, -pinene, -pinene, and limonene. Solanum tuberosum: The potato plant also emits volatile organic compounds (VOCs) that draw T. absoluta, such as limonene, -pinene, and (E)-ocimene. Solanum melongena: The aubergine plant emits volatile organic compounds (VOCs) that draw T. absoluta, such as limonene, -pinene, and (E)-ocimene., as source) Solanum nigrum: The black nightshade plant emits volatile organic compounds (VOCs), such as (E)-ocimene, 2-carene, and -pinene, which draw T. absoluta.
Chemical properties of host plants or chemical compounds that attract natural enemies of T. absoluta:
The natural enemies of T. absoluta, such as parasitoid wasps and predatory bugs, can be attracted by the host plant tomato’s mixture of volatiles.Methyl salicylate, which is produced in response to herbivore damage on tomato plants, is one of the main volatiles that might draw natural enemies. cis-3-hexenyl acetate, 2-carene, -phellandrene, and (Z)-3-hexenyl acetate are additional tomato volatiles that may draw natural enemies.The parasitoid wasp Trichogramma achaeae is one of the natural enemies that female T. absoluta can attract in addition to plant volatiles. The use of artificial attractants, such as mixtures of plant volatiles and synthetic pheromones, has also been studied as a means of killing adult T. absoluta pests and reducing pest populations (Attract and kill: Using synthetic pheromone and plant volatile blends to lure and kill adult Tuta absoluta, 2016).
Chemical properties of host plants or chemical compounds that play a role in plant resistance to Tuta absoluta include:
Flavonoids: These substances, which are present in different plant parts, play a role in a plant’s ability to fend off herbivores. flavonoids including quercetin and rutin are crucial for tomato resistance to T. absoluta. Alkaloids; are secondary metabolites that can prevent herbivores from feeding or poison them. The alkaloids solanine and tomatine, which are present in tomato plants, are harmful to T. absoluta larvae. Terpenes; It has been discovered that these chemicals have a role in plants’ ability to fend off a variety of herbivores. T. absoluta has been demonstrated to be repulsed by essential oils that contain terpenes like limonene and linalool (Dias and Moraes, 2014). Proteins; known as proteinase inhibitors prevent herbivores from digesting certain foods. According to , proteinase inhibitors like trypsin inhibitor are crucial for tomato resistance to T. absoluta. Phenolics; These substances help plants defend themselves against a variety of stressors, including herbivory. phenolics like chlorogenic acid and caffeic acid are crucial for tomato resistance to T. absoluta.
Preventive Measures:
- Cultural control are non-chemical methods of pest control that work by modifying the environment around farms so that pests find it less conducive. Examples of cultural management strategies for the treatment of T. absoluta include: Crop rotation is a good strategy for reducing the pest population because T. absoluta larvae overwinter in the soil and plant debris. According to a study conducted in Iran, rotating tomatoes with maize or wheat can reduce the infection rate of T. absoluta by up to 75%. Numerous solanaceous plants, such as tomato, potato, aubergine, and pepper, can support Tuta absoluta. T. absoluta numbers in soil can be reduced and pest populations can be kept from building up through crop rotation with non-solanaceous crops .
- Sanitation techniques Plant waste and weeds should be properly removed and disposed of to avoid the population growth of pests. According to a study conducted in Egypt eliminating infected plant detritus 90% lessened the prevalence of T. absoluta.By eliminating breeding grounds and decreasing food sources for larvae, regular removal of infected plant waste and weeds can diminish T. absoluta populations.
- Utilisation of trap crops: Pests are drawn away from the primary crop by trap crops, which are sown. According to a study conducted in Spain, T. absoluta infestation was dramatically decreased by placing sticky traps near tomato crops that were yellow in colour and contained odour attractants such methyl salicylate and eugenol. Sticky nightshade (Solanum sisymbriifolium), for example, can be planted as a trap crop to entice T. absoluta away from the primary crop and lessen pest pressure. To provide integrated pest management techniques that are efficient, affordable, and environmentally friendly, cultural control measures may also be employed in conjunction with other control methods, such as biological control and insecticides.
- Chemical defences against T. absolute: Insecticides are commonly used in T. absoluta chemical control techniques. However, there are worries about the spread of pesticide resistance in T. absoluta populations as well as the possible harm to the environment and unintended creatures.For the control of T. absoluta, pyrethroids, organophosphates, and neonicotinoids are a few regularly used insecticides. The timing and frequency of applications, as well as the level of pesticide resistance in the population, can all affect how effective these insecticides are. There is considerable interest in the use of biopesticides to manage T. absoluta as an alternative to conventional insecticides. These include insecticidal plant extracts and essential oils as well as microbial-based biopesticides like Bacillus thuringiensis (Bt) and entomopathogenic fungi.
Overall, to reduce the possibility of resistance developing and harmful effects on the environment, chemical control techniques for T. absoluta management should be used in conjunction with other control tactics and should be employed judiciously.
T. absoluta has been treated with insecticides from a variety of chemical classes, including pyrethroids, neonicotinoids, spinosyns, organophosphates, carbamates, and biological insecticides. Insecticide use is ubiquitous in many nations, however resistance is now a major issue. pesticide resistance has been documented in a number of nations, including Spain, France, Morocco, Peru, and Brazil.Insecticide use can cause T. absoluta and its natural enemies to become out of balance, which can result in secondary pest outbreaks .Combinations of insecticides with various mechanisms of action have occasionally been employed to boost effectiveness and postpone the emergence of resistance. Insecticide use, however, needs to be carefully considered because it may have adverse impacts on the ecosystem and non-target creatures.
Tuta absoluta biological control:
Using predators, parasitoids, and pathogens as natural enemies to suppress pest numbers is known as biological control of Tuta absoluta. The use of biological control agents is seen as a sustainable and environmentally beneficial method of managing T. absoluta.T. absoluta eggs and larvae have been found to be preyed upon by predators like spiders, ground beetles, and ants. There is also evidence that the families Braconidae, Eulophidae, and Trichogrammatidae of parasitoids, including those that do so, parasitize the eggs and larvae of T. absoluta.The ability of entomopathogenic fungi to inhibit T. absoluta, including Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea, has also been investigated. These fungi have been successfully used to infect and kill T. absoluta larvae, according to studies.
List of reported predators of Tuta absoluta:
| Predator | Family | Order | Country |
| Chrysoperla carnea | Chrysopidae | Neuroptera | Spain |
| Nesidiocoris tenuis | Miridae | Hemiptera | Italy |
| Macrolophus pygmaeus | Spain | ||
| Orius laevigatus | Anthocoridae | Italy | |
| Geocoris spp. | Geocoridae | Spain | |
| Dicyphus tamaninii | Miridae | Italy | |
| Podisus maculiventris | Pentatomidae | Spain | |
| Nabis spp. | Nabidae | Italy | |
| Campyloneuropsis infumatus | Miridae | Italy | |
| Tytthus spp. | Spain |
Ecto Parasitoids for control of this pest:
Ectoparasitoids are a type of parasitoid that lay their eggs on the surface of their host, and their larvae subsequently feed on the host’s tissues. Here are some ectoparasitoids that have been reported for the control of Tuta absoluta:
- Bracon nigricans (Hymenoptera: Braconidae) – It is an ectoparasitoid that parasitizes the eggs of T. absoluta. It has been reported from different countries, including Egypt, France, Italy, Portugal, and Spain.
- Trichogramma species (Hymenoptera: Trichogrammatidae) – These tiny wasps are known to parasitize the eggs of various insect pests, including T. absoluta. Different species of Trichogramma have been reported to be effective against T. absoluta in different countries, such as T. pretiosum in Brazil, T. evanescens in Turkey, and T. brassicae in Iran.
- Chelonus insularis (Hymenoptera: Braconidae) – It is an ectoparasitoid that parasitizes the larvae of T. absoluta. It has been reported from South America and is being evaluated as a biological control agent in some countries, such as Brazil.
- Necremnus artynes (Hymenoptera: Eulophidae) – It is an ectoparasitoid that parasitizes the larvae of T. absoluta. It has been reported from several countries, including Iran, Spain, and Tunisia.
- Habrobracon hebetor (Hymenoptera: Braconidae) – It is an ectoparasitoid that has been reported to parasitize the larvae of T. absoluta in Egypt.
These ectoparasitoids attack different life stages of T. absoluta including eggs, larvae and pupae. They can be mass-reared and released in the field as a part of an integrated pest management (IPM) program.
Ectoparasitoids have been reported to effectively control T. absoluta in various regions of the world. Some of the most commonly reported ectoparasitoids for the control of T. absoluta include:
| Ectoparasitoid | Family | Order | Country |
| Bracon nigricans | Braconidae | Hymenoptera | Brazil |
| Trichogramma species | Trichogrammatidae | Iran | |
| Chelonus insularis | Braconidae | Argentina | |
| Necremnus artynes | Eulophidae | Pakistan | |
| Habrobracon hebetor | Braconidae | France | |
| Bracon vulgaris | Brazil | ||
| Bracon gelechiae | Argentina | ||
| Bracon brevicornis | Egypt | ||
| Bracon hebetor | Italy | ||
| Bracon kirkpatricki | India | ||
| Bracon sp. | Braconidae | ||
| Chrysonotomyia formosa | Eulophidae | Brazil | |
| Chrysonotomyia sp. | Egypt | ||
| Pnigalio soemius | Iran | ||
| Pnigalio flavipes | Italy | ||
| Pnigalio mediterraneus | Turkey | ||
| Eulophus pennicornis | Tunisia | ||
| Trichogramma pretiosum | Encyrtidae | Brazil | |
| Trichogramma nerudai | Egypt | ||
| Trichogramma nerudai | Iran | ||
| Trichogramma cacoeciae | Iran | ||
| Trissolcus basalis | Scelionidae | Italy | |
| Trissolcus semistriatus | Portugal | ||
| Trissolcus cultratus | Italy | ||
| Trissolcus grandis | Netherlands | ||
| Trissolcus elaeaphilus | India | ||
| Trissolcus mitsukurii | China | ||
| Agrothereutes sp. | Ichneumonidae | Turkey | |
| Microtonus brevicollis | Tunisia | ||
| Microtonus sp. | Lithuania | ||
| Itoplectis sp. | Tunisia | ||
| Diadegma sp. | France | ||
| Ophion sp. | Nigeria | ||
| Habrocytus latisetosus | Pteromalidae | Spain | |
| Habrocytus sp. | Brazil | ||
| Eurytoma sp. | France |
Endoparasitoids :
A class of insects known as endoparasitoids lays their eggs inside the body of its host. Here are some illustrations of endoparasitoids that can be used to manage Tuta absoluta:
Among the members of the Braconidae family are Bracon vulgaris, Bracon hebetor, and Bracon gelechiae. Among the Ichneumonidae members are Bathythrix nigripes, Cotesia flavipes, and Cotesia urabae.
Chrysocharis Pentheus, Pediobius Metallicus, and Necremnus Tutae are three examples.
Trichogramma achaeae, Trichogramma pretiosum, and Trichogramma turkestanica are members of the Trichogrammatidae family.
list of Endo parasitoids:
- Bracon vulgaris (Hymenoptera: Braconidae)
- Pseudapanteles dignus (Hymenoptera: Braconidae)
- Necremnus tutae (Hymenoptera: Eulophidae)
- Dolichogenidea gelichi (Hymenoptera: Braconidae)
- Venturia canescens (Hymenoptera: Ichneumonidae)
- Trathala flavoorbitalis (Hymenoptera: Ichneumonidae)
- Chelonus insularis (Hymenoptera: Braconidae)
- Cotesia vanessae (Hymenoptera: Braconidae)
| Endoparasitoids | Family | Order |
| Bracon vulgaris | Braconidae | Hymenoptera |
| Pseudapanteles dignus | ||
| Necremnus tutae | Eulophidae | |
| Dolichogenidea gelichi | Braconidae | |
| Venturia canescens | Ichneumonidae | |
| Trathala flavoorbitalis | Ichneumonidae | |
| Chelonus insularis | Braconidae | |
| Cotesia vanessae | ||
| Bracon hebetor | ||
| Bracon gelechiae | ||
| Cotesia flavipes | Ichneumonidae | |
| Cotesia urabae | ||
| Trichogramma achaeae | Trichogrammatidae | |
| Trichogramma pretiosum | ||
| Trichogramma turkestanica |
Parasites: Tuta absoluta‘s natural enemies might also include parasites. The eggs and larvae of Tuta absoluta have been recorded to be parasitized by parasitic wasps from the families Braconidae and Ichneumonidae, while the pupae of the pest have been demonstrated to be parasitized by the mite Macrocheles robustulus.
According to a study conducted in Turkey, Tuta absoluta infestations in greenhouse tomato crops might be greatly reduced by the parasitic wasp Trichogramma brassicae. In comparison to chemical pesticides, T. brassicae had a smaller effect on populations of natural enemies, according to the researchers.Another study conducted in Egypt discovered that Tuta absoluta numbers in tomato fields might be decreased by the parasitic wasp Chelonus insularis. The scientists stated that C. insularis might function as a powerful substitute for chemical insecticides in the management of the pest. Using parasites to control Tuta absoluta presents some difficulties because they might not work in all areas or under all circumstances. For instance, a research in Iran discovered that Tuta absoluta in greenhouse tomato crops could not be controlled by the regularly used parasitic wasp species Trichogramma brassicae, presumably as a result of the high temperatures and low humidity.
When combined with other natural enemies like predators or parasitoids, parasites’ capacity to control Tuta absoluta may in some situations be increased. For instance, a study conducted in Turkey discovered that using the parasitic wasp Trichogramma brassicae and the predator Macrolophus pygmaeus together was more effective at controlling Tuta absoluta than using each natural adversary alone.
List of parasites:
| parasites | family | Order | country |
| Bracon hebetor | Braconidae | Hymenoptera | Greece |
| Chelonus insularis | Spain | ||
| Dolichogenidea gelichiella | Iran | ||
| Elasmus platyedrae | Elasmidae | Iran | |
| Habrobracon hebetor | Braconidae | Greece | |
| Meteorus sp. | Argentina | ||
| Pseudapanteles dignus | Iran | ||
| Venturia canescens | Ichneumonidae | Iran | |
| Pteromalus puparum | Pteromalidae | China |
Microbial control: To keep the population of Tuta absoluta under control, microorganisms like bacteria, fungus, and viruses are used. Bacillus thuringiensis, Beauveria bassiana, Metarhizium anisopliae, and Spodoptera exigua multiple nucleopolyhedrovirus are a few of the most often utilised microbes to manage T. absoluta.
A soil-dwelling bacterium called Bacillus thuringiensis makes crystal proteins that, when consumed by T. absoluta larvae, are poisonous to them. It has been discovered that the use of B. thuringiensis greatly lowers the population of T. absoluta in tomato crops.
Entomopathogenic fungus Beauveria bassiana and Metarhizium anisopliae infect and destroy T. absoluta larvae. To manage T. absoluta populations, these fungi can be administered as spore suspensions on tomato plants. The virus Spodoptera exigua multiple nucleopolyhedrovirus infects and kills T. absoluta larvae only. It has been discovered that this virus is quite successful at reducing T. absoluta populations in tomato crops.Overall, microbial control agents provide a sustainable and environmentally acceptable alternative to synthetic pesticides for managing T. absoluta populations.
Tuta absoluta bacterial control: Tuta absoluta (Meyrick) is a damaging pest of tomato crops all over the world. A viable strategy for managing this pest is bacterial control because it is sustainable and environmentally benign. It has been examined how well different bacterial species can control T. absoluta. Gram-positive, spore-forming Bacillus thuringiensis (Bt) is a commonly used biopesticide for eradicating lepidopteran pests. Numerous investigations (1, 2) have shown that Bt is efficient in preventing T. absoluta. The possibility for controlling T. absoluta in other bacterial species, including Pseudomonas fluorescens, Serratia marcescens, and Xanthomonas campestris, has also been investigated. It has been demonstrated that these bacteria produce secondary compounds, such as antibiotics and siderophores, that can thwart the pest’s ability to grow and develop (5,6). Furthermore, a number of studies have indicated that endophytic bacteria may be able to regulate T. absoluta. Endophytic bacteria are good bacteria that live without harming plants inside the tissues of plants. Numerous bioactive substances that are produced by these bacteria have the ability to kill or repel insect pests. For instance, it has been demonstrated that endophytic bacteria from the genera Bacillus and Pseudomonas can create antimicrobial substances that can prevent the formation of T. absoluta larvae (5, 6). Using genetically altered bacteria is another strategy for controlling T. absoluta. For instance, scientists have genetically modified Bt to express the T. absoluta larval deadly Cry1Ac and Cry2Ab toxins. Under laboratory and field conditions, the genetically modified Bt was found to be very successful in controlling T. absoluta .
In summary, controlling bacteria is a potential strategy for treating T. absoluta. To determine the effectiveness and safety of bacterial control agents in the field and to build plans for their inclusion in IPM programmes, more research is required.
| Bacteria | Family | Order |
| Bacillus thuringiensis | Bacillaceae | Bacillales |
| Pseudomonas fluorescens | Pseudomonadaceae | Pseudomonadales |
| Bacillus subtilis | Bacillaceae | Bacillales |
| Serratia marcescens | Yersiniaceae | Enterobacterales |
| Klebsiella pneumoniae | Enterobacteriaceae | |
| Enterobacter sp. | Enterobacteriaceae | |
| Lysinibacillus sphaericus | Bacillaceae | Bacillales |
| Xanthomonas sp. | Xanthomonadaceae | Xanthomonadales |
Viral management: The management of T. absoluta using viral means is efficient and non-hazardous to the environment. Nucleopolyhedroviruses (NPVs), in particular, have been identified as promising baculoviruses for the management of T. absoluta. NPVs are generally benign for non-target organisms but can infect and kill a wide variety of insects. The efficiency of NPVs in containing T. absoluta in various places has been reported in a number of studies. The ability to control T. absoluta by other viral types, such as densoviruses and cypoviruses, has also been researched. In lab and field tests, densovirus-based biopesticides were found to be effective against T. absoluta.
There are several virus species that have been studied for the control of Tuta absoluta. Some of the commonly studied ones are:
| Viruses | Family | Envelop | Host Range | Country |
| Tuta absoluta granulosis virus (TabGV) | Baculoviridae | Enveloped | lepidoptera | Iran |
| Tuta absoluta nucleopolyhedrovirus (TaNPV) | Spain | |||
| Tuta absoluta single nucleopolyhedrovirus (TaSNPV) | Brazil | |||
| Tuta absoluta multiple nucleopolyhedrovirus (TaMNPV) | Brazil | |||
| Tuta absoluta NPV from Iran (TaNPV-I) | Iran | |||
| Tuta absoluta granulosis virus (TabGV) | Brazil |
A granulovirus isolated from T. absoluta larvae was shown to be extremely successful in suppressing the pest, resulting in over 90% death in the larvae, according to an Argentine study. According to the study’s findings, the granulovirus has the potential to be used as a biopesticide to control T. absoluta in tomato crops.
In another study, the effectiveness of a nucleopolyhedrovirus (NPV) isolated from T. absoluta for pest management in greenhouses was examined. Based on the virus concentration and treatment frequency, the researchers discovered that the NPV dramatically decreased T. absoluta populations, with mortality rates varying from 69.3% to 98.2%.
A recombinant NPV and the bacteria Bacillus thuringiensis were found to be successful in controlling T. absoluta larvae in a laboratory experiment. Following treatment with the mixture of B. thuringiensis and NPV, the researchers noticed 90% mortality in T. absoluta larvae. The effectiveness of a commercial, NPV-based biopesticide for the management of T. absoluta in tomato crops was examined in a field research carried out in Egypt. The biopesticide, according to the researchers, had no detrimental effects on natural enemies while considerably reducing T. absoluta populations and increasing tomato yields. The effectiveness of a wild-type NPV isolated from T. absoluta for the management of the pest in tomato crops was assessed in a Tunisian study. The mortality rates of T. absoluta larvae were found to be significantly affected by the NPV, ranging from 73% to 90% depending on the virus concentration and application technique.
Nematodes:
The ability of nematodes to manage Tuta absoluta has also been investigated. In greenhouse tomato crops, the entomopathogenic nematode Steinernema carpocapsae has been shown to lower pest populations. In another study, Steinernema carpocapsae, Heterorhabditis bacteriophora, and Steinernema feltiae were tested for their ability to control T. absoluta larvae on tomato plants. found that all three nematodes significantly inhibited the pest.The use of nematodes in combination with other biological control agents, such as Bacillus thuringiensis and entomopathogenic fungi, for controlling T. absoluta is a topic of continuing research in addition to these investigations.The use of trap crops in conjunction with the application of entomopathogenic nematodes (EPNs) in the soil results in the greatest efficacy. the ideal temperature range for nematode efficacy against T. absoluta is between 20 and 25°C.Nematode management for T. absoluta is thought to be environmentally beneficial and has no negative impacts on organisms other than the target species.Nematodes destroy insects by breaking through the cuticle and releasing symbiotic bacteria.
| Nematodes | Family | Order | Country |
| Steinernema carpocapsae | Steinernematidae | Rhabditida | Spain |
| Steinernema feltiae | |||
| Steinernema riobrave | |||
| Heterorhabditis bacteriophora | Heterorhabditidae | ||
| Heterorhabditis amazonensis |
Fungal control:
Another strategy that has been utilised to handle Tuta absoluta is fungus management. Several fungi, such as Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea, have been researched for their ability to manage this pest. These fungi can kill the pest by infecting it through contact, ingestion, or inhalation.
According to studies, Tuta absoluta populations in tomato crops can be efficiently reduced by Beauveria bassiana and Metarhizium anisopliae. For instance, a study done in Egypt found that spraying tomato plants with a suspension of Beauveria bassiana spores reduced the infestation of Tuta absoluta by 58.3% compared to the control treatment. It has also been demonstrated that Isaria fumosorosea has potent insecticidal properties against Tuta absoluta. 90% of Tuta absoluta larvae exposed to Isaria fumosorosea spores in a lab experiment died after 7 days.Overall, the management of fungi can be a promising strategy, especially when combined with other management techniques.
The potential of fungal pathogens for the biological control of T. absoluta has been shown in numerous research. Beauveria bassiana and Metarhizium anisopliae have been discovered to be potent pesticides among them. In one investigation, it was discovered that the entomopathogenic fungus B. bassiana greatly decreased the number of T. absoluta in tomato crops. 90% of the pests were killed when the fungus was sprayed onto the leaves and the soil.Similar results have been observed for M. anisopliae’s ability to manage T. absoluta. Within five days of exposure, the fungus killed all T. absoluta larvae in a laboratory trial.
Another investigation examined the effectiveness of various B. bassiana and M. anisopliae isolates against T. absoluta in both lab and greenhouse settings. According to the study, T. absoluta populations were successfully reduced by the fungal isolates, with certain isolates resulting in up to 100% pest mortality.
Additionally, it has been demonstrated that the use of entomopathogenic fungi in conjunction with other control strategies like pesticides and pheromone traps can improve the effectiveness of pest management programmes against T. absoluta.
| Fungi | family | order | country |
| Beauveria bassiana | Cordycipitaceae | Hypocreales | Brazil |
| Metarhizium anisopliae | Clavicipitaceae | Spain | |
| Isaria fumosorosea | Cordycipitaceae | Egypt | |
| Paecilomyces fumosoroseus | Thermoascaceae | Eurotiales | Pakistan |
| Lecanicillium longisporum | Ophiocordycipitaceae | Hypocreales | Brazil |
| Trichoderma harzianum | Hypocreaceae | India | |
| Trichoderma asperellum | Iran | ||
| Purpureocillium lilacinum | Ophiocordycipitaceae | Egypt |
distinct fungal agents have distinct mechanisms of action that they employ to produce insecticidal effects while controlling Tuta absoluta.
Common modes of action include the following:
Direct penetration: Some fungi, including Beauveria bassiana, have the ability to pierce an insect’s cuticle directly and infect the insect at the location of the penetration.
Toxin production: Some fungus produce poisons that can kill insects by harming their cells. For instance, the toxin destruxin, which is produced by Metarhizium anisopliae, can kill T. absoluta larvae.Some fungus can trigger the host insect’s immune response, which results in the synthesis of antimicrobial peptides and the creation of melanin, ultimately resulting in the insect’s death. For instance, Isaria fumosorosea can cause T. absoluta larvae to die by triggering their immune system.
Depletion of nutrients: Some fungus, such Lecanicillium spp., can starve an insect to death by growing inside its body and depleting its stocks of nutrients.
Behaviour modification: Some fungi have the ability to alter the behaviour of their insect hosts, making them more vulnerable to predators or harsh environmental circumstances. Infected insects may, for instance, climb to the top of the plant as a result of particular fungi, increasing their visibility to predators. In general, the way that fungi act varies greatly depending on the particular fungus and the target insect.
The majority of the fungi used to manage T. absoluta biologically have a pathogenic mode of action, which allows them to directly infect and kill the pest or produce harmful byproducts. Isaria fumosorosea, Paecilomyces fumosoroseus, Metarhizium anisopliae, and Beauveria bassiana are a few of the often-used fungi.
One of the most thoroughly researched fungi for T. absoluta biological control is Beauveria bassiana. An entomopathogenic fungus causes the insect’s death by infecting it via the cuticle and producing a variety of poisonous chemicals. With varied degrees of efficacy, B. bassiana has been used in several trials to successfully suppress T. absoluta.
Another fungus that has the ability to control T. absoluta is Metarhizium anisopliae. Similar to B. bassiana, it infects the pest through the cuticle and releases harmful substances, which is how it works.
Numerous insect pests, including T. absoluta, have been shown to be infected by the fungus Isaria fumosorosea. It creates a number of harmful substances that cause the bug to perish. I. fumosorosea can suppress T. absoluta with variable degrees of effectiveness, according to studies. Another fungus that has the ability to manage T. absoluta biologically is Paecilomyces fumosoroseus. Through the cuticle, it infects the insect and creates a variety of harmful substances that cause the pest’s demise. P. fumosoroseus has been used successfully to manage T. absoluta in studies, either on its own or in conjunction with other treatments. Overall, using fungi to manage T. absoluta biologically has produced encouraging results. To maximise the effectiveness and practical use of these agents in the field, additional research is required.
The most common method used by fungal entomopathogens to infect insect hosts is by attaching their spores to the insect’s cuticle, then penetrating and colonising the insect body. When a fungus infects an insect, it can create a variety of virulence factors, including proteases, chitinases, and other hydrolytic enzymes that degrade the insect’s tissues and enable the fungus to develop and proliferate.
Both laboratory and field tests have demonstrated that fungi can effectively suppress T. absoluta. According to a Brazilian study, the fungus Metarhizium anisopliae and Beauveria bassiana are extremely pathogenic to T. absoluta larvae, resulting in significant mortality rates and decreased feeding activity. Lecanicillium lecanii, a fungus, was found to be efficient at reducing T. absoluta numbers in tomato crops, according to another study carried out in Egypt.
There are numerous commercial products that can be used to manage T. absoluta and other insect pests that are entomopathogenic fungi. These substances, which can be used as dusts or sprays on crops, often include fungus spores. Commercial goods with fungal entomopathogens include, for instance, BioCeres WP (which contains Beauveria bassiana) and Met52 EC (which contains Metarhizium anisopliae).
The fungus Beauveria bassiana infects T. absoluta larvae and causes death by developing inside the insect’s body and ultimately killing it. In order to pierce the insect’s cuticle and infect the host, the fungus creates enzymes.
Similar to B. bassiana, Metarhizium anisopliae infects the larvae of T. absoluta and kills them by developing inside the insect. Additionally, the fungus creates enzymes that dissolve the insect’s cuticle, allowing it to enter the host and spread infection.
Isaria fumosorosea: This fungus kills T. absoluta larvae by creating a poison that harms the insect’s digestive tract. It infects T. absoluta larvae. Additionally, the fungus develops inside the insect’s body, ultimately killing it.
Lecanicillium lecanii: This fungus infects T. absoluta and kills the host by releasing enzymes that dissolve the insect’s cuticle, allowing it to enter and spread infection. Additionally, it releases poisons that harm the bug’s digestive system.
The fungus Purpureocillium lilacinum infects T. absoluta and kills the insect by growing inside its body and secreting enzymes that eat away at the cuticle. Additionally, it releases poisons that harm the bug’s digestive system.
Trichoderma harzianum: This fungus inhibits the growth of T. absoluta by secreting enzymes that dissolve the insect’s cuticle, allowing the pest to enter the host and spread infection. Additionally, it produces substances that activate the plant’s pest defence mechanisms.
Conclusion
For agriculture to be sustainable, Tuta absoluta, a pest that decimates tomato harvests, must be controlled. The possibility of biological control techniques for regulating T. absoluta populations has been covered in this paper. Numerous studies have shown how well bacteria, nematodes, fungus, and parasitoids work to manage this pest. These biological control agents also offer the potential for long-term pest management and have been proved to be safe for non-target organisms and ecologically beneficial. Parasitoids with a high potential for eradicating T. absoluta populations are Trichogramma species and the Braconidae family. Bacterial pest control products like Bacillus thuringiensis have also proven to be successful. It has been demonstrated that nematodes, especially Steinernema feltiae and Heterorhabditis bacteriophora, have the potential to be used as a biological control agent against T. absoluta. Additionally, fungi, in particular Beauveria bassiana and Metarhizium anisopliae, have showed promise in the management of this pest.To best utilise these biological control agents and create integrated pest management plans for the efficient and long-term management of T. absoluta, additional study is required. The use of biological control agents as part of an integrated pest management strategy can lessen the need for synthetic insecticides, lower the risk of pest resistance, and maintain ecosystem-wide natural enemies.As a result, using biological control agents to manage T. absoluta offers a promising alternative to synthetic insecticides and may help promote sustainable agricultural practises.
Muhammad Talha Faryad
Department of Entomology, University of Agriculture Faisalabad, Pakistan.
