Pertanika 12(1), 43-46 (1989)

-

COMMUNICATION I

Kesan Pendedahan Racun Karbaril terhadapTumbesaran dan Pembiakan Aphis craccivora Koch

ABSTRAKDalam kajian ini kesan beberapa kepekatan racun karbaril terhadap beberapa parameter jadual hayat Aphiscraccivora Koch telah diselidiki. Telah didapati bahawa karbaril pada kepekatan melebihi 0.0106% b.a.dapat membunuh krsemua nimfa instar awal Pendedahan pada kepekatan ini pula mengakibatkan kele-watan pembiakan selama tiga hari pada tiga peratus daripada populasi dewasa yang telah didedahkan danumur hidupnya hanya 10 hari, iaitu suatu kesingkatan hayat yang bererti berbanding dengan 29 hari dalamkawalan. Nilai-nilai parameter jadual hayat juga menunjukkan bahawa populasi aftd yang berkenaan tidakakan bertambah dan oleh itu tidak mampu melanjutkan hayatnya ke generasi hadapan. Sebaliknya terdapat8% yang mencapai kedewasaan bagi populasi yang terdedah kepada kepekatan 0.0052% b.a., 40% bagikepekatan 0.0027% b.a. dan 68% bagi kepekatan 0.0013% b.a.

ABSTRACTThe effects of several concentrations of carbaryl on the life-table parameters of Aphis craccivora Koch werestudied. It was revealed that all the early nymphal instars died after being exposed to carbayrl at concentra-tion in excess of 0.0106% a.L Exposures at this concentration however, resulted in a 3-day delay in re-production in 3% of the tested population and experienced a significantly shorter life span of 10 days whencompared to 29 days in the control. Values for the life-table parameters also indicated that these populationswould not grow and thus would be unable to continue into the next generation. In contrast, 8% of the popu-lation exposed to 0.0052% a.i. reached adulthood, 40% for those exposed to 0.0027% a A. and 68% forthose at 0.0013% a.i.

PENGENALANAfid atau kutu daun melalui kitaran hidup yangagak luar biasa dan lazimnya mempunyai kadarpembiakan yang tinggi. Ianya berkebolehanmelahirkan progeni secara berseks atau tidakberseks, iaitu partenogenesis. Di dalam iklimtropika seperti Malaysia ini afid Aphis craccivoraKoch yang merosakkan tanaman kekacang,kukurbit, dsbnya, membiak dengan cepatdengan ketiadaan halangan dari faktor cuaca.Pada suhu serta kelembapan yang tinggi kadarpembiakan dan kesuburan afid ini adalah tinggijuga (Radke, et al, 1972).

Selain dari menghisap cairan sap tana-man, afid ini juga berkemungkinan berfungsisebagai vektor penyakit virus pada tanamankekacang, cili dan kukurbit. Oleh itu kawalankimia secara meluas bukan lagi perkara asing.Pada kes-kes tertentu racun serangga padakepekatan submaut telah merencatkan pem-biakan serangga dan hamama (Hall, 1979Jones

dan Parrella, 1984). Ada juga kes-kes lain yangmenunjukkan perangsangan racun serangga inimenyebabkan kenaikan kadar pembiakan yanglebih tinggi, iaitu suatu keadaan yang digelarhormoligosis (Luckey, 1968). Di Tamil Nadu,India, populasi Aphis gossypii telah didapati ber-tambah sungguhpun semburan racun seranggatelah dilakukan. Keadaan ini telah dikaitkandengan letusan semula populasi akibat rang-sangan pembiakan yang tebih tinggi padakepekatan submaut di lapangan (Sithananthan,et al., 1973).

Kajian ini telah dijalankan untuk menen-tukan kesan racun karbaril terhadap keupayaanpembiakan A. craccivora Koch.

BAHAN DAN KAEDAH

Kultur AfidKultur stok telah dimulakan dengan seekor afidbetina yang dipelihara pada pokok kacang

YUSOF BIN IBRAHIM DAN WONG KUAN YEOW

tanah, Arachis hypogaea var. Matjan, dalam in-sektarium pada suhu 24°C - 32°C dan kelem-bapan bandingan 46% - 90%. Pokok-pokokkacang tanah ini telah dipastikan bebas dariserangan Iain-lain serangga dan penyakit. Ke-segaran kultur stok ini dijaga dengan mengawalsaiz populasi dan menyalinkan pokok-pokokkacang tanah yang segar setiap empat hari.

RawatanUntuk rawatan, nimfa-nimfa instar pertama darigenerasi ketiga yang telah dilahirkan dalamjangka masa 24 jam telah digunakan.

Sebagai substrat rawatan, pokok kacangtanah yang subur dan berumur 10 hari telahdigunakan. Setangkai daun yang tidak terasingdari pokoknya telah dicelupkan ke dalam ban-cuhan rawatan racun karbaril atau air sulingdan dibiarkan kering udara selama setengahjam. Bancuhan rawatan racun karbaril (Sevin85WP) yang digunakan ialah pada kepekatan0.0106%, 0.0053%, 0.0027% dan 0.0013% sertaair suling yang merupakan rawatan kawalan.Seterusnya, nimfa instar pertama telah dipin-dahkan secara cermat dengan berus halus (000Series Finest Sable, Winsor & Newton) kepadadaun yang telah dirawat. Nimfa afid ini kemu-diannya membesar di dalam sangkar mikro yangdiperbuat dari dua potongan paip PVC ber-garis pusat 5 cm setebal 5 mm sebagai rangka.Sangkar mikro ini ditutupi dengan kepinganPVC lutsinar nipis yang berlubang-lubang halusuntuk penyaliran udara. Dalam membentuk satusangkar mikro, tetali span dikepitkan di antaradua rangka PVC tersebut untuk mengelakkantangkai daun daripada tercedera. Untuk men-jamin kesihatan afid dan mengelak pertum-buhan kulat, sangkar mikro ini sentiasa diber-sihkan dari madu serangga dan wap air.

Data dan PenganalisisanSetiap hari pada waktu yang sama bilangan afidyang mati dan yang masih hidup, iaitu datakemandirian, serta nimfa yang dilahirkan telahdicatat bagi setiap afid secara individu sehinggaianya mati. Setelah dibilang, nimfa-nimfa telahdinyahkan daripada sangkarnya. Prosedurjadual hayat standard telah diikuti dalam mem-buat penganalisisan data untuk mengira para-meter-parameter seperti kadar pembiakan kasar(GRR), kadar pembiakan bersih (Rf)), kadar

intrinsik pertambahan (r) dan masa puratagenerasi (T) (Southwood, 1978). Min daripadaempat replikat yang setiap satunya mengan-dungi 10 afid bagi setiap rawatan telah di-bandingkan dengan cara analisis varian dua haladan ujian julat berganda Duncan (DMRT).

KEPUTUSANKadar kemandirian terkhusus umur bagi A. rrac-civora setelah dirawat dengan beberapa ke-pekatan racun karbaril (Rajah 1) telah didapatimenurun bersamaan dengan kenaikan ke-pekatan rawatan. Masa tumbesaran nimfa kedewasa ialah 4 hari. Bagi rawatan yang terpekatsekali (0.0106%), hanya terdapat tiga peratusnimfa afid yang mencapai peringkat dewasaberbanding dengan 98% dalam kawalan. Se-terusnya, terdapat lapan peratus mencapaikedewasaan bagi kepekatan 0.0052%, 40% bagikepekatan 0.0027% dan 68% bagi kepekatan0.0013%. Rawatan pada dua kepekatan tertinggijuga mengakibatkan umur afid pendek, iaitu 10dan 12 hari jika dibandingkan dengan 29 haridalam kawalan.

Rajah 1. Kemandirian Aphis craccivora Koch yangdipelihara atas pokok kacang tanah yangtelah dirawat dengan karbaril di dalamkeadaan insektarium.

Secara amnya, corak pembiakan A. crac-diwaadalah agak sama bagi kesemua kepekatanrawatan (Rajah 2). Kadar pembiakan didapatilebih tinggi pada peringkat awal dewasa yangkemudiannya menjadi semakin berkuranganmulai umur lapan hari. Puncak pembiakan padakesemua rawatan ialah pada hari ketujuh ke-

PERTANIKA VOL. 12 NO. 1, 1989

KESAN PENDEDAHAN RACUN KARBARIL TERHADAP TUMBESARAN DAN PEMBIAKAN A CRACCIVORA KOCH

cuali afid yang dirawat dengan 0.0106% b.a.yang mana puncak pembiakannya hanya di-capai pada hari kesepuluh. Tambahan pulapuncak pembiakannya didapati 41 kali lebihrendah daripada kawalan. Bagi kepekatan yanglebih rendah, pendedahan kepada 0.0053%,0.0027% dan 0.0013% masing-masing menun-jukkan puncak pembiakan 29, 2.4 dan 1.3 kalilebih rendah daripada kawalan. Panjangnyajangka masa pembiakan juga didapati lebihpendek bagi afid yang dirawat berbandingdengan kawalan. Pada kepekatan 0.0106% dan0.0053%, afid hanya berupaya membiak selamaempat dan lapan hari sahaja berbanding de-ngan 22 hari pembiakan bagi kawalan. Ini ber-makna masa pembiakannya telah dipendekkan5.5 dan 3.0 kali berbanding dengan kawalan.

Jadual 1 menunjukkan parameter-para-meter jadual hayat afid yang telah dirawat dandipelihara di atas pokok kacang tanah. Padakawalan didapati bahawa kadar pembiakan kasar(GRR) ialah 47.06 nimfa dan kadar pembiakanbersih (Ro) ialah 42.13 nimfa. Kedua-dua para-meter ini memberikan nilai yang agak tinggidan menunjukkan perbezaan yang bererti se-tidak-tidaknya bagi afid-afid yang telah dirawatdengan kepekatan karbaril yang melebihi0.0053%. Begitu juga halnya dengan masapurata generasi (T) yang telah dipendekkandari 11 kepada 5 hari pada kepekatan 0.0053%dan 2.6 hari sahaja pada kepekatan 0.0106%yang mana telah mengakibatkan berkurangnyakadar pertambahan saiz populasi. Ini amatketara sekali apabila dilihat dari segi kadarintrinsik pertambahan (r) yang mencatatkanpertumbuhan negatif dan juga dari segi kadar

J.2 16 20

Umur ( H a r i )

Rajah 2. Kesuburan Aphis craccivora Koch yangdipelihara atas pokok kacang tanah yangtelah dirawat dengan karbaril dalam keadaaninsektarium.

finit pertambahan (X) populasi yang mencatat-kan nilai kurang dari satu. Parameter masaganda dua (DT) tidak menunjukkan perbezaanyang bererti (P=0.05).

JADUAL 1Jadual hayat Aphis craccivora Koch yang

dipelihara atas pokok kacang tanah yang telah dirawat dengan karbaril dalam insektarium.

Kepekatan(% b.a.)

0.01060.00530.00270.0013Kawalan

GRR

2.25a

2.38a

41.46b

43.93b

47.06b

0.225a

0.450a

15.401b

27.670c .42.130d

Parameter

T

2.61a

5.07a

11.06b

11.29b

11.31b

r

- 0.053a

- 0.003ab

0.250bc

0.290c

0.330c

31

0.25a

0.46a

1.28b

1.34b

1.39b

DT

-17.32 a

3.02a

2.81a

2.42a

2.12a

Min-min dalam ruang yang sama dan diikuti dengan huruf yang sama adalah tidak mempunyai perbezaan yang berertipada paras P < 0.05 setelah diuji dengan ANOVA dua hala dan DMRT.

PERTANIKAVOL. 12 NO. 1, 1989 45

Pertanika 12(1), 47-51 (1989)

COMMUNICATION II

The Rate of Litter Production in Mangrove Forest at Siar Beach,Lundu, Sarawak

ABSTRAK

Penyelidikan kadar pengeluaran sesampah huian bakau telah dilakukan di Pantai Siar, Lundu, Sarawak.Huian ini mempunyai sembilan spesies pohon; spesies pohon yang dominan ialah Rhizophora mucronata,sementara R, apiculata sebagai spesies kodominan. Kadar pengeluaran sesampah ialah 5. 72 t/ha/tahun,dan dari jumlah ini 4.49 t/ha/tahun (78.5%) adalah serasah daun. Corak kadar pengeluaran sesampahdan serasah daun berubah antara satu bulan dengan lainnya. Pengeluaran sesampah antara bulan Aprilhingga Jun dan Disember hingga Februari lebih banyak berbanding dengan bulan-bulan lain.

ABSTRACT

A study of litter production was conducted at Siar Beach, mangrove forest, near Lundu, Sarawak. There arenine species of trees in this forest of which Rhizophora mucronata is the dominant and R. apiculata is theco-dominant species. The rate of litter production xoas 5.72 t/ha/year, and of this 4.49 t/ha/year (78.5%)was leaf litter. 'The production of litter fluctuates being higher during April to June and December to Februarycompared to other months.

INTRODUCTION

Mangrove trees serve many functions. Theecological functions of mangrove as a landbuilder and coastline stabilizer have beendescribed by McNae (1974) and de la Cruz(1979). Heald and Odum (1970) describedmangrove as a spawning and nursery area forfishes and prawn. These functions, are closelyrelated to the primary productivity of themangrove. Several authors have conductedstudies on the relationship of primary produc-tivity of mangroves and its ecological and eco-nomic functions (e.g. Golley et al. 1962; Healdand Odum 1970; Odum 1971). They foundthat most of the organic debris that enrichedthe estuary were derived from adjacent mang-rove forest. Thus, litter production plays an im-portant role in maintaining the fertility of themangrove ecosystem and supply of food mate-rial to the faunal life (Srivastava 1980). How-ever, the rate of litter production varies fromplace to place, and between species dominatingthe site (Mathias 1974). Such differences canbe seen from the work of Heald (1971) inFlorida, Christensen (1978) in Thailand and

Gong et al. (1984) in Matang mangrove forest,West Malaysia.

The production of litter of the mangroveforest at Siar Beach, near Lundu was studied inorder to understand more about the producti-vity of mangrove ecosystems in Sarawak.

Study AreaThe study area is located at Siar River Estuary,between latitudes 109° 52' E to 109° 53' E andlongitudes 1° 44' to 1° 45' N (Wolfenden andHaile 1963). The estuary is about 12 km N - Eof Lundu (Fig. 1). The river is about 2 m wideat low tide and 4 m wide at high tide.

The area is dominated by Rhizophoramucronata and R. apiculata is co-dominant(Saberi 1984). The other species that can befound in the area are Bruguiera gymnorrhiza, B.parviflora, B. cylindrica, Avicennia alba, Lumnitzerasp., Nypa fruticans, Oncosperma sp. and a fernAcrosticum sp.

The soils of the area derived from biotiteadamellite rocks. The climate is reasonably wet,highest precipitation occurring in January, andlowest in March. The total precipitation is 4260mm per year. The temperature varies between

SABERI OTHMAN

SOUTH CHINA SEA

Kuching 1 ° 4 1 ' N-

u

48

Fig. 1. Star beach of Lundu, Sarawak.

PERTANIKA VOL. 12 NO. I, 1989

THE RATE OF LITTER PRODUCTION IN MANGROVE FOREST AT SIAR BEACH, LUNDU, SARAWAK

25° - 28°C, the lowest being in January andhigher in May (Fig. 2).

Fig. 2. The climatic diagram for Kuching, Sarawak.

MATERIALS AND METHODSPlant litter was collected in a trap made of sail-cloth, with a square wooden-frame openingmeasuring 50 x 50 cm. The trap was placed lmabove the ground. Fifteen such litter traps weresited randomly beneath the trees, and theircontents were emptied at the beginning of eachmonth. The litter was sorted into leaves and amiscellaneous component. The litter was washedand oven-dried at 105°C to constant weight.

RESULTS AND DISCUSSIONThe suitable size and form of litter-trap forsampling litter-fall in a tropical rain forest is notknown. A study of previous work shows that avaried size of litter-traps were used. The small-est was 45 x 45 cm (Woodroffe 1982) and thelargest was 200 x 200 cm (Duke et al. 1981).The form of the trap also shows variation. Mason(1970) had used round shaped traps instead ofsquare, and Kira et al. (1967) used a long beltof plastic net as the trap. In this study a trapwith a square opening measuring 50 x 50 cmwas used. This size is within the range of thetrap used by previous workers, and easy tohandle while in the forest.

The total small litter and leaf litter pro-duction varies between forest and climaticregions. Generally leaf litter accounts for morethan 50% of the total litter produced. However,the amounts of this litter may vary dependingon the size of the traps used. For some forests,particularly mangrove, leaf litter could reach ashigh as 80%. A similar high percentage (78.5%)of leaf litter was detected in the mangrove forestat Siar Beach (Fig. 3).

50"

40

1 | Leaf-litter

p^l Miscellaneous

Fig. 3. The pattern of litter fall for 1983 and 1984 in a standof Mangrove forest, Siar Beach, Lundu, Sarawak.

The mean values obtained for the mixedmangrove forest at Siar Beach are 5.74 and 4.49t/ha/year for total small litter and leaf litterrespectively. These values are significantly lowerthan those obtained for many tropical rain forest(e.g. Nye 1961; Bullock 1973; Gong et al. 1984).The leaf litter of this forest is about 40% lowercompared to the values obtained for othermangrove forests. This could be due to the factthat the mangrove forest at Siar Beach is not asdense compared to other forests. Such situationshave been highlighted by Gong et al (1984)for Matang mangrove forest, and Woodroffe(1982) for Tuff Crater, mangrove forest, Auck-land New Zealand. The density of trees at SiarBeach is 166/ha (Saberi, 1984), and this value

PERTANIKA VOL. 12 NO. 1, 1989 49

SABERI OTHMAN

is about four times lower compared to other fo-rests such as at Banyu Asin, Sumatera (Soekardjoand Kartawinata 1979), Sabah, Malaysia (Liew1977) and in Florida, U.S.A. (Pool et al. 1977).However, there is no data available for compa-rison on the relationship between density andlitter production in mangrove forests.

Litter production increased in March andApril and reached its highest rate in May. Itsubsequently dropped in June, July and Augustand remained constant till November. It thenincreased again in December and reached itssecond peak in February. A similar pattern inlitter fall has been reported for Pasoh (Lim1978), Matang mangrove forest (Gong et al.1984) and R. apiculata in Phuket, Thailand(Christensen and Wium-Anderson, 1977). Thehigh production in May coincide with hightemperature and draught. Gill and Tomlinson(1969 & 1971) in their studies of the red mang-rove in South Florida, report peak rates of leaffall and growth during summer months whenair temperature and incident light were at theirannual peaks. Similar results have been reportedby Heald (1971). Snedaker and Lugo (1973)found indications that leaf fall increases duringdry periods. According to Lugo and Snedaker(1975) the timing of these events has a signifi-cant interaction with the hydrologic budget andprimary productivity of the forest community.The higher production in February cannot beexplained in terms of biological processes.However, its does coincide with heavy winds ofthe South China Monsson and rainfall. Occa-sional storms have been reported to coincidewith increased litter fall (e.g. Pool et al. 1975;Goulter and Allaway 1979).

Production of litter is relatively continu-ous, thus supplying the detritus food chain. Thefraction exported to adjacent sea areas is notknown, but many leaves are carried away bytides, especially at spring tides, before anydegradation takes place.

SABERI OTHMAN

DepartTnent of Biology,

Faculty of Science and Environmental StudiesUniversiti Pertanian Malaysia43400 UPM Serdang Selangor Darul Ehsan,Malaysia,

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PERTANIKA VOL. 12 NO. 1, 1989 51