LEAF TORTRICIDS (LEPIDOPTERA, TORTRICIDAE) INHABITING APPLE ORCHARDS OF THE VICINITY OF LUBLIN PART II. DOMINATION AND FREQUENCY STRUCTURE AND SIMILARITY OF SPECIES COMPOSITION

Izabela Kot¹, Bożenna Jaśkiewicz^2
1 Department of Entomology, University of Life Sciences in Lublin, Poland
² Department of Entomology, University of Agriculture in Lublin, Poland

ABSTRACT

Results presented in this paper are a continuation of studies the results of which are included in part I. They were concerning the species composition and number of leaf tortricids in apple orchards characterized by varying degrees of anthropopressure. The purpose of the studies presented in part II was to establish the structure of domination and frequency as well as the similarities of the species composition of leaf tortricids. The greatest differentiation of the domination structure of leaf tortricids was observed in the orchard without any plant protection. The group of eudominants included one species in the unprotected orchard, while in the other two, where protective treatments were performed, two species of leaf tortricids were included in each. Euconstants, which are the species of the highest frequency, were found out only in the orchard without any chemical protection. The smallest similarity of the species composition between leaf tortricids was observed between the orchard without any chemical control and the intensively protected one.

Key words: leaf tortricids, Lepidoptera, Tortricidae, apple orchards, domination, frequency structure, similarity of species composition.

INTRODUCTION

Domination refers to a single species and points to the latter’s quantitative share in the studied ecosystem. The size of the domination depends on a number of ecological factors and it changes in the same groups in particular years. The structure of domination is related to the number of particular species in biocenosis, while domination classes are distinguished considering the number of species in groups [1, 3]. Frequency defines the degree of the species’ link with the environment, pointing to its commonality or rarity. The value of the frequency index is affected by the number and distribution of species as well as their requirements towards the environmental conditions [3].

Results presented in this paper are a continuation of studies the results of which are included in part I concerning the species composition and number of leaf tortricids in apple orchards in the vicinity of Lublin. The purpose of the studies presented in part II was to establish the structure of domination and frequency as well as the similarities of the species composition of leaf tortricids occurring in apple orchards characterized by varying degrees of anthropopressure.

MATERIALS AND METHOD

The area and methods of studies concerning leaf tortricids occurring in apple orchards are thoroughly presented in part I. While characterizing the quantitative relations and the structure of particular communities the studies made use of two ecological indexes, namely domination and frequency [3, 5]. Domination index (D), in other words defined as relative abundance (A_r), was calculated according to the following formula:

where: n_a – number of individuals belonging to a given species in all samples,
n – number of individuals of a studied systematic group in all samples.

Frequency index (F), also defined as constancy of occurrence (C), is expressed in the percentage of samples in which a given species occurred. This index was calculated according to the following formula:

where: q – number of trials when a given species was noted,
Q – number of all samples.

The present paper treats a single observation as a sample.

The following classes of domination and frequency were distinguished on the basis of the indications included in Kasprzak and Niedbała’s [3] study:

Similarity of the species composition (MS) was determined on the basis of Marczewski-Steinhaus’s formula [3]:

where: a – number of species of one community,
b – number of species of the second community,
w – number of species common to both the compared communities.

RESULTS AND DISCUSSION

Table 1 includes domination structure, table 2 presents frequency structure of leaf tortricids, while table 3 similarity of the species composition between leaf tortricids in particular apple orchards in the years of studies. Figure 1 presents changes in the structure of domination of some species of leaf tortricids in particular years of studies.

In the orchard without any chemical protection in Leonów only Archips rosana (Photo 1), in the case of which the index of domination was 41.0% in the years 1999-2001, was included within eudominants (tab. 1). In the same orchard subdominants included Hedya nubiferana and Pandemis heparana. Recedents comprised 3 species, and subrecedents – 5 species of leaf tortricids. The domination index for particular species of Tortricidae took considerably differentiated values in successive years of studies. The domination of Archips rosana decreased from 62.0% in 1999 to 46.3% in 2000 and 26.3% in 2001, while the domination of Spilonota ocellana (Photo 2, 3) increased from 2.6% in 1999 to 12.6% in 2000 and 33.1% in 2001 (fig. 1). The domination index of Adoxophyes orana reached the highest value of 16.3% in 2000, whereas in the other two years of observations it stayed at a similar level of about 10%. Significant differences were noted in the domination of Pandemis heparana, whose value in 1999 reached 20.8%, and then it went down by 5.2% in 2000 and 3.6% in 2001.

In the orchard of a limited program of plant protection in Motycz two species of tortricids: Adoxophyes orana and Archips rosana, whose index of domination was close to each other and was equal to 34.3% and 31.4%, respectively, were included in the class of eudominants. Dominants also comprised two species Pandemis heparana and Hedya nubiferana, while the classes of subdominants and recedents were formed by one species of leaf tortricids each. No species was included within subrecedents. The highest coefficient of domination was characteristic of Adoxophyes orana in the first year of studies. It was 60.0% and next it decreased to 33.3% in 2000 and 27.8% in 2001 (fig. 1). The domination index of Archips rosana ranged from 41.7% in 2000 to 20.0% in 1999. Archips xylosteana and Hedya nubiferana occurred only in 2001 and their domination index was 11.1% and 22.1%, respectively. The domination of Pandemis heparana in all the years of observations stayed at the level of 10-20%.

In the intensively protected orchard in Jastków the three-year-long studies found out only three species of leaf tortricids: Archips rosana, Pandemis heparana and Adoxophyes orana, out of which only the last species was in the group of dominants, while the other two were classified as eudominats (tab. 1). In 1999 and 2000 the domination of Archips rosana was 33.3 and 75.0%, respectively. On the other hand, in 2001 the presence of only this species was observed and hence its domination index was 100% (fig. 1). The index of domination of Pandemis heparana in 1999 and 2000 ranged from 25.0 to 33.3%. Adoxophyes orana was observed only in 1999, its domination being 33.3%.

In the orchard with intensive plant protection the number of leaf tortricids was four times as low as in the orchard without any chemical protection, and its structure of domination was the least differentiated. Eudominants and dominants constituted 100% of all the observed species of leaf tortricids. It results from the fact that man’s strong and varying interference leads to the formation of entomocenonses with poor species composition with a high population of a small number of species and lack of species of the lowest population. This leads to a decrease of species biodiversity and points to environmental synanthropization [4, 6]. In the orchard with a limited program of plant control eudominants and dominants constituted more than 90%. The domination structure found out in the intensively protected orchard and in the orchard with a limited program of plant protection is characteristic of so-called degraded decay [6]. On the other hand, the domination structure in the orchard without any plant protection was shaped in a differed way: only Archips rosana was included to eudomiants and the domination index of this species was 41.0%. Spilonota ocellana and Adoxophyes orana were dominants, while Hedya nubiferana and Pandemis heparana were subdominants. The class of recedents was made of 3 species, while the class of subrecedents comprised 5 species.

Regarding frequency, in the orchard without chemical protection the class of euconstants included two moth species Pandemis heparana and Adoxophyes orana, that occurred in the greatest number of samples. The classes of constants and subconstants included 4 species each, while accessory species included 3 species of Tortricidae (tab. 2). No species was included in the class of euconstants in the orchard with a limited program of plant protection. Only Adoxophyes orana occurred in such a number of samples that made it possible to include it in constants. Archips rosana and Pandemis heparana was found in the class of subconstants, while Archips xylosteana, Hedya nubiferana and Pandemis cerasana were defined as accessory species. In the intensively protected orchard no species was included within the classes of euconstants and constants. Only Archips rosana was a subconstant, whereas Pandemis heparana and Adoxophyes orana was classified within accessory species.

Qualitative similarity (MS) of the species composition of leaf tortricids in the studied experimental objects determined according to Marczewski-Steinhaus’s formula is presented in table 3. This coefficient assumed the lowest value in the orchard without chemical protection and in the intensively protected one (MS = 23.0%). On the other hand, the greatest species similarity was characteristic of the orchard with a limited program of plant protection and the intensively protected orchard (MS = 50.0%). Similar results were obtained by Gantner [2], comparing the occurrence of different lepidopterous insects in hazel plantation with different intensity of plant protection.

CONCLUSIONS

1. The greatest differentiation of the domination structure of leaf tortricids was observed in the orchard without any plant protection.

2. The group of eudominants included one species in the unprotected orchard, while in the other two, where protective treatments were performed, two species of leaf tortricids were included in each.

3. Euconstants, which are the species of the highest frequency, were found out only in the orchard without any chemical protection.

4. The smallest similarity of the species composition between leaf tortricids was observed between the orchard without any chemical control and the intensively protected one.

REFERENCES

1. Czachorowski S., 2004. Opisywanie biocenozy – zoocenologia, skrypt elektroniczny dla magistrantów [Describing of biocenosis – zoocenology, script for MA candidates]. www.uwm.edu.pl/czachor/publik/pdf-inne/zoocenozy.pdf

2. Gantner M., 2003. Lepidoptera of hazel plants in Poland (part I). Occurrence, species, composition and economic importance. EJPAU, 2003, 6, 2, Horticulture. http://www.ejpau.media.pl

3. Kasprzak K., Niedbała W., 1981. Wskazniki biocenotyczne stosowane przy porzadkowaniu i analizie danych w badaniach ilosciowych. [W:] Metody stosowane w zoologii gleby (red. Górny M., Grüm L.) [Biocenotic indexes used in arrangement and analysis of dates in quantitative studies. [In:] Methods used in soil zoology]. PWN Warszawa, 397-416 [in Polish].

4. Pisarski B., Trojan P., 1976. Wpływ urbanizacji na entomofaunę [The influence of urbanization on entomofauna]. Entomologia a ochrona srodowiska. PWN, Warszawa, 65-76 [in Polish].

5. Szujecki A., 1980. Ekologia owadów lesnych [Ecology of forest insects]. PWN Warszawa, pp. 603 [in Polish].

6. Trojan P., 1998. Nowe perspektywy w badaniach entomofaunistycznych [New perspectives in entomofaunistic studiem]. Wiadomosci Entomologiczne, Poznań, 17 Supl., 137-155 [in Polish].

Accepted for print: 16.01.2007

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