1. Introduction
The rise in migration from villages to urban cities, resulting in rapid growth of cities, with concrete buildings, apartments, business centres, the walls separating the private estates from one another and paved roads have impacted the natural landscape space and created generally unsightly structures. Therefore, in order to form more appealing living areas and to reduce daily stress and troubles, ornamental plants have been used in parks and gardens, along the highway medians, on balconies and in houses. However, there are many harmful factors damaging to such plants and one of the most important such factors are insects.
The aim of this study was to identify the insect species responsible for damage to saplings and ornamental plants in the province of Bartın and its environs. For that reason, research has been carried out in that province and its close environs, such as Safranbolu, Karabük, Çaycuma, Devrek and Mengen. In this region, many herbaceous and woody ornamental plants are cultivated in parks and gardens, which are either regional or were imported from other regions for landscape design purposes. Woody plant saplings have been used in parks and gardens as well as in the afforestation areas and highways. Cultivating these materials and ensuring their long-term permanence with regards to landscape beautification is a crucial issue. It has been observed that in the parks and afforestation areas intensely damaged by the insects, the plant productivity, landscape unity and aesthetics have been devastated.
Toper [1] has identified 16 insect species on poplar trees in Bartın. Lodos et al. [2] have listed a total of 178 species of Scarabaeoidea in Turkey between 1979–1987. Thirty nine of these species were collected in Bartın and its vicinity. Arslan [3] has recorded about 25 insect species cusing damage to elm, common alder, maple and willow in the Bartın region. Özkazanç [4] has recorded 16 insect species damaging to oak, beech, and hornbeam trees in Bartın forests, but so far there has not been any recorded study of insect species damaging to ornamental plants and saplings in Bartın. Özbek et al. [5] have given information about pests of vineyards, orchards and ornamental plants. Toros [6] and Toper [7] have treated park and ornamental plants pests, damages and controls in their instruction books.
It is estimated that hazardous organisms and micro-organisms like plant diseases, insects and weeds cause 33.7% economical damage before and after the harvesting season. The distribution of this damage could be broken down into due to 12% plant diseases, 12% to insects and 10% to weeds. This ratio makes up about one third of the world's plant production potential including ornamental plants. The economical losses due to plant diseases in the Unites States reached 9.1 billion dollars. The insects caused 7.7 billion dollars and weeds caused 6.2 billion dollars of damage [8].
The maritime temperate climate affects the province of Bartın. The summer seasons occasionally have a high relative humidity ratio and a regular temperature while the winter seasons are seasonably characterized by the climate of Black Sea. However, as a river surrounds the province, the relative humidity is often recorded as remarkably high. According to the meteorological data, the temperature in summer ranges between 23 and 25 °C while in winter, it ranges from 0 to 10 °C. The average annual number of rainy days ranges from 100 to 130, and the regional humidity ratio is approximately 75% [9]. It was within this environment that most of the research was undertaken.
2. Material and Methods
The main material of this study covers the ornamental plants, saplings and young trees existing in the province of Bartın and its vicinity and the insects damaging them. The research, dating back to 2004 and 2005, has been carried out initially in the campus of Z.K.U. Bartın Faculty of Forestry and in all of the gardens, parks, afforestation areas, greenhouses and afforested parts of the highways in the province of Bartın. Having been detected throughout the field trips arranged on various days, the insect species were collected, brought to the lab and put into the collection boxes prepared. The location place, date, and the host plant of each sample was recorded and it was photographed with a Nikon camera. A SMZ-U Stereomicroscope was used to photograph much smaller insects.
Aphids (winged and wingless), gathered with a thin brush made of sable, were put into 70% alcohol. The specimens were preserved using Hille Ris Lambers's method [10]. For the preservation of scale insects, the Potassium Hydroxide method [11] was used.
For the preservation and collection of other insects, the method of Çanakçioğlu [12] was used and the identification of insects was carried out using different literature sources [6, 7, 13–18]. Sarıbaş, Kaya and Yılmaz identified the host plants. Ornamental and Houseplants [19], Botanica [20], Biotopes Mapping in Bartın Province and near vicinity [21], Houseplants [22] and The Most Beautiful Wild Flowers of Turkey [23] were principally used as the source for the identification of some plants.
4. Discussion
According to the previous research carried out in the province of Bartın and its vicinity, it has been observed that ornamental plants and saplings have been widely and beneficially used both in indoor and outdoor living spaces (such as gardens and balconies) of private and official establishments in order to embellish the environment and to form much more attractive and appealing living areas. This has created a considerable demand for ornamental plants and this demand has been satisfied by forests, nurseries and shops that cultivate and sell ornamental plants.
In this research, it has been determined that among the seasonal ornamental plants, Rosa sp., Populus and Salix species, Euonymus, Dieffenbachia, Pinus, and Morus alba “pendula”’ are subjected to the most intense insect damage. As far as this study is concerned, 34 harmful insect species belonging 6 genus and 20 families have been identified in the regional parks and gardens where the ornamental plants are cultivated. It has been also observed that Unaspis euonymi Comst, Macrosiphum rosae L., Chrysomela populi L., Thaumetopoea pityocampa Schiff., Aphis gossypii Glov., Philaenus supumarius L., Crepidodera aurata Marsh., Gryllotalpa gryllotalpa L. and similar species have been the most numerous. Leucaspis pusilla Löw., Plagiodera versicolora Laich., Melolontha melolontha L., Polyphylla fullo L., Lymantria dispar L., Thaumetopoea pityocampa Schiff., Trialeurodes vaporariorum Westw and Gryllotalpa gryllotalpa L. can be classified among the primary physiologically damaging insects that have been distinguished in this research.
The most damaging species detected in the genus Lepidoptera living in the afforestation areas and saplings planted areas by means of landscaping design has been Thaumetopoea pityocampa. Despite its low density, Lymantria dispar is one of the species that makes its presence be felt almost every year. These moths must be monitored in terms of their biology, expansion and hosts. Although almost every reference book state that the species named as Libythea celtis feed on the leaves of Celtis australis, it has been observed in the field trips and laboratory studies that the caterpillars of this moth also eat the leaves of Alnus glitunosa ssp. glutinosa.
The damage caused by Plagiodera versicolora of genus Coleoptera, which was almost an epidemic disease for willows and aspens in previous years must be taken into consideration for uture plant protection. The adult and larvae of this insect pest caused damage to leaves by eating and skeletonising them. Moreover, they can cause severe retardation of growth and they sometimes cause host death. Chrysomela populi also damages the leaves of poplars. When in large numbers occur they destroy shoots and decrease wood quality. As a result, when the woody shoots are not fully bloomed, they are negatively affected by frost, so special attention that is required to minimise the damage of poplar saplings. The damage that Crepidodera aurata caused was by making holes on the leaves and skeletonising. It has been noted that although Cetonia aurata, Melolontha melolontha, Polyphylla fullo species were found in the province every year, the numbers were low and their damage is low compared to other species except Melolontha melolontha.
The presence of Aphis farinosa, Aphis nerii, Macrosiphum rosae, Chaitophorus leucomelas, Aphis fabae, Aphis gossypii, Myzus persicae, Leucaspis pusilla, Unaspis euonymi, Eulachnus rileyi, Trialeurodes vaporariorum, Coccus hesperidum, Coccus longulus, Pseudaulacaspis pentagona, Cicadelle viridis, Philaenus supumarius and Cercopis vulnerata species of the genus Hemiptera in the province has been confirmed. Compared to the other species, only the population of Cercopis vulnerata species has been marked as low. Coccus hesperidum has been observed as having a rather high population density on Dieffenbachia plants and thus causing the death of its host plant. Unaspis euonymi has been found in high numbers on the branches, stems and leaves of the cherry laurel (Euonymus latifolius ve Euonymus japonicus cv. “Aureopictum”), which is used abundantly in park and landscaping designs, and it has been observed that this insect causes the drying out of cherry laurels and severe retardation in their growth. It has been observed that the same insect is a pest on Ficus starlight, where it concentrates on the spot where the lamina is joined to the stem and on the bottom and upper surfaces of the leaves. However, as its population increases gradually, the damage it causes is more widespread leading to the early fall of leaves.
Although Gryllotalpa gryllotalpa of genus Orthoptera (Gryllidae) has been detected on the road between Ağdacı Village and Bartın Faculty of Forestry, the fact that it is widely disseminated throughout the province can be also learnt from the villagers when they are asked to talk about the features of their environment. It is quite thought provoking that the rather good recognition of this insect by the inhabitants of this city, where 70% of its population is dependent on agricultural production, indicates the extent of the damage and harm that this insect causes. It has been also observed that the grasshopper of Gryllus desertus species does not cause much damage compared to the formerly mentioned one.
Forficula auricularia of order Dermaptera has been stumbled across in various places, and as yet, no significant damaging effects have been noticed.
When the insect species and their pests that are encountered and found in the province reconsidered, the necessity of giving priority to the global studies about the precautions related with the prevention of insect pests has come to the foreground. Firstly, the factors that pave the way for the causes and effects rises in the insect pest populations must be determined. Secondly, the biological control mechanisms that act against these insects must be investigated and put into practice. Thirdly, the predators feeding on harmful species, if any, must be protected and provided with reproduction and growth opportunities. Lastly, the application of an integrated pest management (IPM) strategy formed by incorporating other control techniques may be considered in the regions where the damage is highly visible.
In Bartın and its vicinity, as long as the utmost care is shown to the plants used indoors and outdoors spaces and necessary precautions are taken in case of the possible disasters caused by insect pests, much healthier and good-looking finer plants will surround our environment.