Aleurotrachelus trachoides Back’s (Hemiptera: Aleyrodidae) preference on different host plants

One invasive pest that has affected vegetable crops is the whitefly. Aleurotrachelus trachoides Back is a newly discovered whitefly pest that affects a number of horticultural crops. This study assessed Aleurotrachelus trachoides Back.’s preference (antixenosis) for eggplant, tomato, chili, okra, and cucumber. It also analyzed at the relationship between the quantity of eggs and early instar nymphs per plant and the morphology of the leaves (trichome, epidermis, palisade, and thickness). In January 2018, A. trachoides was taken from the Bambu Kuning Greenhouse at the National University in Jakarta. This study was carried out in June and July of 2018 at the Cikabayan Greenhouse, IPB University, Bogor, using a randomized complete block design with three replications (@2 plants/genotype). Eggplant (cv. Ratih Ungu) had the highest amount of A. trachoides eggs and early instar nymphs, followed by okra (cv. Nayla), tomato (cv. New Mutiara), cucumber (cv. Maestro), chili (cv. Kastilo), and chili (cv. Yuni). A. trachoides had a preference for tomatoes, chilies, and eggplant (Solanaceae family). The number of eggs and early instar nymphs per plant did not correlate with the different host plants’ leaf morphology. A. trachoides favored the genotype on chilies that had more non-glandular trichomes.


Introduction
Whitefly is a polyfag insect and invasive species [1].The spread of whitefly continues to increase [2].One of the major pests in Indonesia and other Asian nations, Australia, Sub-Saharan Africa, the Mediterranean, and the Middle East is the whitefly [3].One of the causes is the export of inter-country plants where eggs, nymphs, and pupae are carried on the leaves [4].Some types of whiteflies that attack vegetable crops in Indonesia are Bemisia tabaci Genn, Trialeurodes vaporarium Westwood, Aleurodicus dispersus Russell, Aleurodicus dugesii Cockerell, and Aleurotrachelus trachoides Back [5].Whitefly causes damage directly and indirectly.Whitefly sap and suck the plant liquid to cause damage to cells and leaf tissue.In heavy attacks, plants can become dehydrated and leaves turn yellowish, wilt, and die.Whitefly is also a vector of various viruses such as Begomovirus genus (Geminiviridae), Crinivirus (Closteroviridae), Carlavirus or Ipomovirus (Potyviridae).
Whiteflies widely spread in the low-land until middle-land [6].The whitefly, Aleurotrachelus trachoides/Aleurothrixus trachoides Back (Hemiptera: Aleyrodidae), caused damage in some areas of Florida [7].The whitefly is a Neotropical pest that has spread to India [8], Brazil [9], Tanzania [10], and Indonesia such as Jakarta, Bogor, West Sumatra [11], and Southeast Sulawesi.It has the ability to spread 1302 (2024) 012029 IOP Publishing doi:10.1088/1755-1315/1302/1/012029 2 globally through the movement of infested plants.A. trachoides can inflict economic damage due to its rapid population growth, particularly in locations where it is isolated from its natural enemies.This species has been found on over 34 distinct plant families however it is most commonly found on Solanaceae.
It is not known to vector any plant viruses initially.In seven areas in Southeast Sulawesi, the average incidence of yellow leaf curl disease ranged from 36% to 90%.Aleurotrachelus trachoides was the species of whitefly that was discovered [12].It has been discovered that A. trachoides can spread the Duranta leaf curl virus (DLCV) to potatoes, bell peppers, and tomatoes.These findings imply that A. trachoides' status as a virus vector has to be reevaluated.This will have a significant impact on the cultivation of solanaceous vegetables in the world.
The mechanism of self-defense of plants against pest infestation consists of three mechanisms, namely antixenosis, antibiosis (resistance), and tolerance.Non-preference or antixenosis is a passive defence mechanism.Antixenosis depend on form of leaf morphology such as trichomes, cuticles, leaf tissue composition, and odor to resist the presence of pests.Antixenosis can be evaluated by number of eggs, reducing the number of pest colonies [13].Explained that antixenosis is a rapid test method to determining whitefly preferences [14].Antibiosis is the ability of plants to limit and reduce the proliferation of pests after contact with plants.Tolerance is a plant that continues to grow, develop and produce despite an attack of pests [15].
Aleurotrachelus is a globally distributed genus and can adapt quickly to new areas.Pesticides are used to protect the crops.The use of synthetic insecticides has caused problems for the environment.Large amounts of wax can be produced by nymphs, which can protect them against pesticides.The use of natural enemies, biopesticides, and biological control agents has become an alternative option in integrated pest management [16].
Aleurotrachelus trachoides was known as solanum or pepper whitefly.This species is mostly found on solanaceaous plants.As a result, the goals of this investigation were to: assess Aleurotrachelus trachoides Back's choice for eggplant, tomato, chili, okra, and cucumber; and examine the relationship between A. trachoides's preferences and leaf morphology (trichome, epidermis, palisade, and leaf thickness).From the result of this study, it will be known preference for A. trachoides.

Study area
Whitefly A. trachoides were obtained from pepper plants in the Bambu Kuning Greenhouse, National University, Jakarta in January 2018.Then they were brought and reared at Cikabayan Greenhouse, IPB University, Dramaga, Bogor by using eggplant as host plants.Whiteflies, that were used for infestation, is confirmed to be non-viruliferous (does not contain viruses) [17].This study was carried out at the Cikabayan Plastic House, IPB University, Bogor in June until July of 2018.The location is 200 meters above sea level, with daily temperatures ranging from 30-36 degrees Celsius and humidity levels between 75 and 81%.

Plant material.
The genetic material used were chili (Capsicum annuum L.) variety Yuni, Kastilo and Laris, eggplant (Solanum melongena L.) variety Ratih Ungu, tomato (Solanum lycoperssicon L.) variety New Mutiara, cucumber (Cucumis sativus L.) variety Maestro and okra (Abelmoschus schimosus L.) variety Nayla.Seed seedling was carried out in the screen house to avoid unwanted insect attacks.Plants were grown from seeds sown in 50-celled plastic tray.Two seeds were sown in each cell of the plastic tray containing media.A month later it was moved to a small polybag measuring 15x20 cm.A mixture of soil, manure and husks were used for transplanting media.During the experiment no spraying of insecticides was carried out to avoid the use of chemical residues against experimental residues.The provision of plant nutrition is carried out by applying AB mix leaves once every week since 1 WAP (Weeks After Planting).Plant material used for research is 4-6 leafy plants or 4 WAP.

Preference testing.
Host plants are used 4-6 leaves or 4 WAP and antixenosis testing was used the free choice test method in insect greenhouses.Whiteflies were infested, assuming 10 imago per plant, and placed in plastic glass in centre of plants at insect cage measuring 1x0.6x1 m.Whiteflies were taken from the whitefly population in a 1x0.6x1 m insect cage by aspirator.After 7 days whiteflies were taken and returned to the insect cage.The environmental design used was a randomized complete group design with host plant genotypes as treatment.The number of genotypes used was 7 genotypes with three replications, so there were 21 experimental units.Each genotype in each replication consists of two plants.The total plant population is 46 plants.Observation of the number of eggs carried out on the 7th day after infestation and instar 1 and 2 were done on the 10th day after infestation with the help of digital microscope 10x magnification [18].

Leaf morphology analysis.
Observations of plant tissue and trichomes were carried out in the Plant Ecophysiology Laboratory, Faculty of Agriculture, IPB University.The leaves used were the 3rd and 4th leaves.The leaves of the plant were cut using a sharp razor vertically.Plant tissues were viewed in a microscope connected to a computer for the calculation of the size of the leaf tissue.Samples from the center of the leaves were cut into pieces measuring about 10x10 mm 2 and then placed on object glass.The number of trichomes were calculated using digital microscope 10x magnification.Observation of the number of trichomes was carried out with the help of a digital microscope 10x magnification [19].

Data analysis
Analysis of the data used is the Normality-test at the 5% level to meet the assumptions ɛij ~ N (0, ϭ2); normal spread error, middle value µ, and homogeneous variance.Furthermore, the data was tested by ANOVA (F test), if the real treatment at the level of 5% was continued with Least Significant Difference (LSD).Software tools using Microsoft Excel 2013, Minitab 14 and SAS 9.1.Data on the number of eggs per plant and the number of early instar nymphs were transformed by √ (X).

Results and discussion
Whitefly adult of B.tabaci and A. trachoides are rather difficult to distinguish, but the early instar nymphs can be distinguished.The early instar A. trachoides nymphs are also oval, yellowish in color and on the dorsal side there were eight patches.The nymph then develops to become black and covered with a layer of wax like cotton.Damage symptoms of A. trachoides are presence of white, waxy material (Figure 1).

Number of egg/plants, number of early instar nymph/ plant and percentage of egg hatching/plant
The response of A. trachoides to the parameters of the number of eggs per plant was different (Table 1).The highest number of A. trachoides eggs per plant was in eggplant, followed by chili cv.Kastilo, cv.Yuni and tomato.Instead of that, cucumber has not significant difference with okra on A. trachoides eggs/plant.The percentage of hatching A. trachoides eggs more than 80% in chili cv.Yuni, Kastilo, tomato and eggplant (Table 1).Eggplant is the preferred host plant by A. trachoides.

Leaf morphology
Eggplant, tomato and cucumber have higher trichome density than chili (Table 2).Okra has the longest palisade and thickest epidermis.Result from Table 1 showed that okra has low number of eggs/plant of A. trachoides.The antixenosis (preferences research) parameters are the quantity of eggs and nymphs.A low number of eggs and nymphs per plant indicated that the whitefly did not favor the host plant, but a high number of eggs and nymphs per plant indicated that the whitefly preferred the host plant.The whitefly lands on the leaf and begins probing.Following that, it would feed, and the female whitefly would then lay eggs.Before deciding which plants to consume, whiteflies received input from their mechanosensory, gustatory, olfactory, and visual senses [20].
Table 3 showed that the number of eggs and early instar nymphs per plant of A. trachoides did not correlate with the morphology of the leaves.Different responses of the host plants may be due leaf morphology such as trichomes, epidermis, and leaf thickness.A. trachoides preferred eggplant, tomato and chili compared to cucumber and okra. A. trachoides is a polyfag insect but have preference in a Solanaceae family.In India A. trachoides attacks on the Solanaceae family are more severe than other families.
Quick and high reproduction rate were the character of invasive pest.Because of its quick growth, it has the potential to outcompete a native species.It should be able to live on a range of food sources.Host plants of A. trachoides, in addition to Solanaceae, were Ipomoea batatas (Convolvulaceae), Duranta erecta (Verbenaceae), Leucaena leucocephala (Fabaceae), Cleodendrum inerme (Lamiaceae), Plumeria alba (Apocynaceae), Tabebuia avellanedae (Bignoniaceae), Tectona grandis (Verbenaceae), Argyrea cuneata (Convolvulaceae).
Chili cv.Yuni was a susceptible genotype while cv.Laris was a resistance genotype.There was a difference in response of A. trachoides between chilli genotypes that are susceptible and resistant.This response due to chilli leaf morphology.Heavy attack A. trachoides of on the genotype of the Yuni could result in the death of the plant (unpublished data).A. trachoides prefers host plants with a higher proportion of non-glandular trichomes.Bemisia tabaci prefers chili with more non-glandular trichome.Herbivore growth, survival, reproduction, and dynamics of population can be influenced by both the quantity and quality of host plant.The high non-glandular trichomes provides a more humid microclimate and indirectly protects the eggs [21].

Conclusions
A. trachoides preferred eggplant, chili and tomato.There was no correlation between A. trachoides's preferences and leaf morphology (trichome, epidermis, palisade, and leaf thickness). A. trachoides preferred to choose host plants with more non-glandular trichomes.The high non-glandular trichomes provides a more humid microclimate.

Table 1 .
Number of eggs/plant and number of early instar nymphs/plant of A. trachoides.
Notes: Values are means ± SE.Means followed by different letter are significantly different based on LSD test at the level of 5%.