Temesgen Fita, Mulatu Wagari
Orthezia insignis Browne (Homoptera: Ortheziidae) is native to South and Central America, but is now widespread throughout the tropics including South eastern Ethiopia. It is one of the newly emerging invasive alien species invaded Ethiopia. The insect was first observed on Lantana camara in Haramaya University compound. In its first observation the pest species was unknown. For identification of the insect leaf samples were taken from infested lantana and seen under dissecting microscope in Haramaya University Plant Protection Laboratory. During investigation clear pictures and movie videos were taken from the sample leaves by digital camera. The samples were sent to the “South African Agricultural Research Council” and on April 29, 2016 the team responded as the insect is “Orthezia insignis.” The clear statement of the South African Agricultural Research Council declared that “the insect is not regarded as a biological control agent of lantana, since it was never intentionally selected, imported, studied or released against the plant. O.insignis is a generalist garden pest that also includes Lantana camara amongst its wide range of host plants. It can be quite damaging if it occurs in large numbers, and in addition to sucking the plant saps, its secretion of honeydew causes black sooty mildew to grow on the plant, thus further reducing the photosynthetic area of the plant. However, it does not have the potential to control L. camara effectively, since the plant is extremely resilient and can outgrow the damage”. Data collected from field survey revealed that at Haramaya University compound from the sampled 5 sites of 50 lantana patches 3 (60%) sites and 26 (52%) lantana patches were infested by O. insignis. At Haramaya district of the sampled two Administrative kebeles, Adelle and Walembo (Awaday areas) from 20sites of 200 lantana patches 15 (75%) sites and 142 (71%) lantana patches were infested. At Harari Administrative Regional State of the sampled two Administrative kebeles (Hashange and Gube Mirkannsitu) from 20sites of 200 lantana patches 13 (65%) sites and 139 (69.5%) lantana patches were infested by O. insignis. At Babille district there was no infestation of O. insignis in all sampled 2 adminstrative kebeles of 20 sampled sites and 200 lantana patches. Damage rating of O. insignis was made by setting damage rate scale as: 0%=0 insects per leaf 6%=1-35 insects per leaf; 7 to 13%=36-80 insects per leaf; 14 to 40%= 81-220 insects per leaf, 41 to 60% = 221-350 insects per leaf; 61-80%= 351- 450 insects per leaf, and more than 80% =>451 insects per leaf. Based on these scale the result of O. insignis damage ratting shows that the list and highest population density on single leaf was from 12- 663 adults and crawlers of O. insignis. From the total sampled 240 leaves 12 (5%) were free of O. insignis infestation, and the rest 228 (95%) leaves were infested from the least count of Orthezia, which ranges from 12 to 663 per leaf. The population count for all infested leaves were; 27(11.25%) leaves from 1-35 insects per leaf, 55(22.9%) leaves from 36-80 insects per leaf, 68 (28.3%) leaves from 81-220 insects per leaf, 42(17.5%)leaves from 231-350 insects per leaf, 19(7.9%) leaves from 351-450 insects per leaf and insects count per leaf on 17(7.1%) leaves were greater than 451 O. insingnis, in which 663 insect per leaf was the highest count. The mean average leaf damage was 68% in which the population density on a single leaf counted was 81-220 O. insignis per leaf. From this summary it is possible to conclude that there was high aggregation of O. insignis on a single leaf which may causes high damage on the host. Amongst its wide range host plants, O. insingnis was artificially introduced on two economically important plants (potato and tomato) by putting single infested leaf of L. camara on top of ten potted host plants and on ten potted non-host plant, Parthenium hysterophorus. After three days of artificial introduction the pest was transferred to these potted plants and highly reproduced in number. After thirty days of introduction Parthenium plant start to dry due to high aggregation of O. insignis on stem and leaf than potato and tomato plants. To see the population of O. insignis on non host potted plants of P. hysterophorus, 2cm length of stem and leaves were taken randomly from four plants at bottom, middle and top portion of the plant. The average counts of O. insignis per cuttings were 36, 40, 44 and 32 for stem and 26, 30, 23, and 31 for leaves. The results of artificial introduction of O. insignis on to these host and non-host plants (potato, tomato and P. hysterophorus, respectively) shows for O. insignis dissemination the only important thing is mechanisms of dissemination. If it will be aided by mechanical agents like animals, plant materials, activity of human beings, wind and water, it will be disseminated easily and attack economically important crops and endogenous plant species. From less mobile nature of the insect if immediate measure will be taken, it can be contained on its spot area with no or less dispersible. If it will be left as a simple thing, the fate that the other countries are facing now will be much more in case of ours. Its early establishment on non-host plant including its polyphagous nature, will indicate us the insect is terrible pest and it can attack all economically important horticultural and fruit crops including legume crops, leading to food security problems and other social problems.
Orthezia Insignis, Invasive, Infestation, Damage, Host and Non-Host.