Feeding Preference on Rutaceou Preferences Of
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Jurnal Natural Vol. 10, No. 1, 2010 FEEDING PREFERENCE S OF Papilio polytes L. L ARVAE ON RUTACEOUS HOST PLANTS Suwarno Department of Biology Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam - Banda Aceh Abstract . The food preference of the Papilio polytes L. larvae on four rutaceous host plants, Citrus aurantifolia (Chrism.) Swing, Citrus reticulata Blanco, Citrus hystrix DC, and Murraya koenigii (L.) Sprengle, were investigated on July to December 2006, in the laboratory of entomology School of Bio logical Science University Sains Malaysia Penang . The two-choice and four-choice food preference tests of the larvae on host plants leaves were conducted. The first instar of P. polytes larvae significant preferential feeding ( P < 0.05) for a host plant in all paired host plant leaves combinations tested, except for the C. hystrix and C. reticulata combination. Furthermore, the third instar larvae had significant preference for leaves of the three Citrus species over M. koenigii, while the third instar larvae showed no significant feeding preference among the Citrus spp. Indiscriminately feeding shown on the fifth instar larvae on leaves of all Citrus species but consistently consumed less M. koenigii compared to Citrus spp. in th e various combinations tested. The first and the third instar larvae of P. polytes were more selective in terms of feeding than the fifth instar. The nitrogen content in leaves of all four host plants differed significantly ( P < 0.01), with C. reticulata was the highest (4.52%), while the water content of leaves was significantly the lowest in M. koenigii (71.72%), compared to the three Citrus species (76.38 – 79.12%) among which the water content did not significantly differ. Key words : Food preference, host plant, larvae, Papilio polytes , nitrogen and water content detoxification by larvae [1,4 ]. The compensatory I. INTRODUCTION response of P. polytes on host plant quality typically falls into three different categories : Papilio polytes L. (Lepidoptera : Papilionidae) is increased rates of food intake, consumption of known to feed on various genera of Rutaceae. In additional plant tissue that complements the the forests, the larvae of P. polytes was found on limiting nutrient, and increasing digestive Murraya, Triphasia, Glycosmis, Zanthoxylum, efficiency of limiting nutrient [6]. Toddalia, Evodia, and Poncirus . In recent years, this butterfly has adapted to the urban/suburban The ability of immature i nsects to discriminate host environments and is found to feed on citrus plants for feeding based on the quality of the host plant [1]; this feeding adaptation has made P. polytes a can be important in crop pests because of the role potentially serious pest in citrus orchards. of non-crop plants as alternate hosts [8]. The larvae of Manduca sexta L. that feed on an inferior host Most obviously, the host plant is one of the most plant would be moving to search for a more suitable important environmental aspects for the developing host [9]. Many insect herbivores change the quality of offspring [2]. Adults butterfly exhibit oviposition their host plants, affecting both inter - and intraspecific preferences corresponding to chemicals interactions [10]. experienced during development [3,4]; and hosts plants may differ chemically [5]. More subtle Understanding the feeding preference of various differences in nutrients, nitrogen and water content host species of P. polytes is an important are also present between host species, affecting life prerequisite for developing pest management cycle and larval performance of P. polytes [6,7]. strategies for this insect. Various studies have investigated the relationship between adult host The utilization of one or the othe r alternative host preference and larval performance by using this plant on butterflies is it potentially involves assumption [11, 12]. The objective of the present differences in host searching by females, host study was to eval uate the feeding preference and recognition by females and larvae, metabolization and Feeding preferences of Papilio polytes L. larvae on rutaceous host plants (Suwarno) ___________________________________________________________________________________________________________ selectivity of different larval stages of P. polytes on First instar larvae four host plant species. Two-choice test II. MATERIALS AND METHODS The methodology for this test was modified after The insect DiTommaso and Losey [13] and Ghumare and Mukherjee [14] and the test was conducted for a 24 Larvae of P. polytes were collected on July 2006 h period. All possible paired combinations for the from Citrus trees on the campus of Universiti Sains two-choice test of the host plant leaves ( C. Malaysia, Penang. The collected larvae were reared aurantifolia – C. hystrix, C. aurantifolia – C. on Citrus microcarpa in the laboratory condition at reticulata, C. aurantifolia – M. koenigii, C. hystrix 24-26 oC, 60-85% relative humidity, and a – C. reticulata, C. hystrix – M. koenigii and C. photoperiod of L12:D12, until adult emergence. reticulata – M. koenigii ) were evaluated using petri The larvae were placed in a screen cage measuring dishes (each 10 cm diameter). One of very young 50 x 50 x 50 cm. Ten pairs of the emerged P. leaf of each Citrus species (approximately 2 cm polytes adults were transferred to a field cage (4 m long, 1 cm wide, and weighed 10-12 mg), and three width, 6 m length and 2 m high) to facilitate mating young foliages of M. koenigii approximately equal and oviposition. Flowers of Ixora sp. were supplied in size and weight to the Citrus leaves were used as food for the caged adult P. polytes . The flowers for the first instar larvae experiment. The leaves contained in a glass jar filled with water were were collected from the respective plants and the sprayed with 10% sucrose solution twice daily to end part of their petiole was wrapped with ensure sufficient provision of nectar, and placed in moistened cotton to prevent dehydration prior to the cage; the flower were replaced every two days. placing them in the petri dish. Thereafter, twenty newly hatched P. polytes larvae starved for 4-5 h Host-plants were introduced in each petri dish containing the respective combination of leaves and allowed to Selection of the rutaceous host plants for this study feed on the leaves for 24 h period. The leaves in was based on their potential value as commercial each petri dish were weighed at the beginning of plants. Three commercially grown Citrus species, the experiment and reweighed 24 h post feeding by [C. aurantofolia (Christm.) Swing., C. hystrix DC ., the first instar larva. The water loss from the leaves C. reticulata Blanco], and a partially domesticated in each petri dish due to evaporation was estimated rutaceous species, M. koenigii (L.), were used in by placing a piece of young leaf of each Citrus spp. this experiment. Twenty young seedlings of each (and three young foliages in the case of M. species were used as food resources. The host koenigii ) in each of ten petri dishes (10 cm plants were separately planted in plastic bags (each diameter) prepared as in the two-choice bag 25 cm diameter and 35 cm high) containing a combination. The leaves in each of these petri 3:1:1 mixture of podsolic, compost and manure, dishes (without larvae) were weighed twice, at the respectively. Each plastic bag contained one beginning of the experiment and later at 24 h. Thus, seedling of a single species. Each seedling was the weight difference indicated water loss due to fertilized fortnightly with 10 g of artificial fertilizer evaporation. The larval consumed was recorded and 100 g manure. from weight of leaf before introduced to larvae subtract the weight of leaf after 24 h and mean of Feeding preference water losses. Both feeding preference of the first instar and leaves water content were replicated 10 Three larval stages, the first, the third and the fifth times. instars, were used in this experiment. Preliminary studies were conducted to determine the amount Four-choice test (weight) of leaves consumed in 24 h by each larval stage. Based on the average weight of leaves of The experimental design for the four-choice test each host plant consumed in the preliminary trial by was similar to the two-choice test, except that one the first, third, and fifth instar larvae (first instar: 5- very young leaf of all three Citrus (C. aurantifolia, 6 mg/10 larvae, third instar: 30-32 mg/5 larvae and C. hystrix and C. reticulata ) and three young fifth instar: 55-60 mg/larva), the weight of leaves foliages of M. koenigii were offered in the same for this feeding experiment was determined. All petri dish to the first instar larvae. Each of the ten larval instars were fed with leaves from the four petri dishes prepared for this experiment contained host plants using the two-choice and four-choice leaves of all four host plants approximately equal in experiments. size and weight. Twenty newly hatched P. polytes larvae starved for 4-5 h were introduced into each dish. The leaf host in each dish was weighed before the larval introduction and at 24 h post-introduction 22 Feeding preferences of Papilio polytes L. larvae on rutaceous host plants (Suwarno) ___________________________________________________________________________________________________________ of the larvae. The water loss from each petri dish young leaves of M. koenigii similar in size and due to evaporation was estimated by weight to the Citrus species were used. Each of the simultaneously running additional 10 petri dishes ten petri dishes prepared for this experiment without larvae as described above for the two- contained leaves of all four host plants choice test. approximately equal in size and weight. The vegetation in each dish was weighed before the Third instar larvae larval introduction and at 24 h post-introduction of the larva.