Journal of Tropical Forest Science 10(2): 167-175 (1997)

BIOLOGY OF RETORTA (: NOCTUIDAE), A NEW PEST OF IN PENINSULAR MALAYSIA

Ahmad Said Sajap, Yaacob Abd. Waha Aidab& h Marsidi

Department of Forest Management, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

Received October 1994______

SAJAP, A.S., YAACOB, A.W AIDAH& . . 1997M , . Biolog f Spiramayo retorta (Lepidoptera: Noctuidae), a new pest of Acacia mangium in Peninsular Malaysia. An outbreak of (Lepidoptera: Noctuidae), affecting 800 ha of a one-year- old Acacia mangium plantation, occurred in May to October 1992 in Gunung Besaut Forest Reserve, Perak, Peninsular Malaysia. In the laboratory, more than 60% of larvae reared on A. mangium leaves reached adult stage. Development from egg to adult took 42 days through seven instars requiring 27 days. The was medium - sized, having red abdomen and an eyespot on its forewing. The female (x = 64.4 mm), bigger than the male, had greyish-orange forewings with prominent eyespots. e male( d Th darha 58.x= ) k brow8mm o almost n t black forewings with less conspicuous eyespots. The life table parameters recorded from laboratory popula- tion were: the net reproductive rate (Ro) of 203.2, the mean generation time (Tc) of

43.3 days intrinsie th , c ratdoubline increasf th eo d an g edays1 6 tim(r0. 5. mf f .e)o o Results from biweekly sampling showed that the infestation, indicated by the numbe f treeo r s with larvae, variebeginnine th t studye da th fro % f go m, 30 ros o et fourte more th th n ei f h o thawee % dropped d n60 en kan e th leso dt t a s tha% n10 fourteenth week. Three tachinids, Carcelia sp.,Exorista Blepharellad an . sp sp., emerged from field collected larvae. Larval-pupal mortalit parasitiso t e ydu 5.6-43.3%s mwa . Predators, Sycanus leucomesus (Reduviidae), Cantheconidea furcellata (Pentatomidae), () and indosinensis () were observed feedin larvaee th n go .

Keywords: Acacia mangium - outbreak - Spirama retorta

SAJAP, A.S., YAACOB, A.W AIDAH.M& . . 1997. Biologi Spirama retorta (Lepidoptera: Noctuidae), serangga baru Acacia mangium i Semenanjund g Malaysia. Satu wabak serangan rama-rama Spirama retorta (Lepidoptera: Noctuidae), berlaku di ladang a Acaciah 0 80 mangium berumur setahun padhinggi aMe a Oktober 199 i Huta2d n Simpan Gunung Besaut, Perak, Semenanjung Malaysia. Di makmal lebih daripada 60% larva yang diberi makan dau. mangiumA n mencapa peringkae k i t dewasa. Pembesaran daripada telur ke dewasa mengambil masa selama 42 hari melalui tujuh instar dalam mas hari7 a2 . Rama-ram berukurai ain n sederhana, abdomen berwarna merah dan mempunyai tanda berbentuk mata pada sayap hadapan. Rama-rama betin 64. = ) lebi x 4( amm h besar daripada rama-rama jantan, mempunyai sayap berwarna kelabu oren dengan tanda mata yang jelas. Rama-ramajantan (x = 58.8 mm) mempunyai sayap berwarna perang hitam dengan tanda matanya tidak jelas. Parameterjadual hayat yang direkodkan dalam makmal menunjukkan nilai kadar pembiakan bersih bersamaan (Ro) 203.2 tempon ,mi h generasi (Tc) 43.3 hari, kadar

pembiakan intrinsik (rm) 0.1 dan tempoh mengganda bersamaan 5.6 hari. Keputusan dari penyampelan setia mingga pdu u menunjukkan kadar serangan naii d k dar% i30

167 8 16 Journal of Tropical Forest Science 10(2): 167 5 (1997-17 )

awal kajian ke 60% di minggu keempat dan terus menurun ke 10% di akhir minggu keempatbelas. Tigalalattachinid, Carceliasp.,Exoristasp.d3.n Blepharellasp.,menje\ma. daripada larva yang diambil dari lapangan. Parasitisma ini rnenyebabkan kematian larva-pupa diantar - 43.3% 6 5. a . Pemangsa, Sycanus le.ucome.sus (Reduviidae), Cantheconide.a furcellata (Pentatomidae), Mallada basalis (Clirysopidae n Vespada ) affinis indosinensis (Vespidae) didapati memakan larva serangga ini.

Introduction

Many developing countries including Malaysia replenish their diminishing forest resources by adopting a reforestation programme involving the planting of fast- growing exotic species. In Malaysia, about 500 000 ha of unproductive forest have been alienate r establishmenfo d f foreso t t plantations dato T . e approximately 100 000 ha of forest plantations have been established, 90% of which are being planted with Acacia mangium Willd. Acacia mangium is a fast-growing leguminous tree indigenous to Northern Australia, Papua New Guinea and Irian Jaya. The tree ca hignm gro5 h3 witwo t straighha t bole measurin diameten i m c t breas5 rga 3 t height (Li e mharvesteb n 1993)ca pulpwoor t I fo d. fiv n di seveo t e n yearsr o , sawlog productioyears5 1 o t . 2 1 n ni Like many exotic plants, A. mangium trees are exposed to the risk of diseases and pests. Many indigenous are associated with this tree and some of these insects may pose a serious threat to the forest plantation industry (Abe 1983, Hutacharern 1993, Chey 1996). One insect discovered attacking A. mangium plantation recently was Spirama relorta (Clerck) (Lepidoptera: Noctuidae). In May 1992 majo,a r outbrea f thiko s pest occurre one-year-ola n di . mangiumdA stan Gununt da g Besaut Forest Plantation, Sungkai, Perak outbreae Th . k affected aren . a abouf ha ao 0 80 t Spirama retorta is a relatively rare indigenous moth. Heretofore, very little informatio s distributioit n no d hosan n t plant s availablewa s o . YunuH d an s (1980), Barlow (1982), Robinson et al. (1994) and Chey (1996) did not document this rnot thein i h r respective books mothe Th . , however presens wa , Thailann ti d hoso n tt plan bu gives wa t n (Hutacharer : Tubti& n m 1995) earln A . y report showed that this insec d beeha t n foun feeo t dAlbizzian o d le.bbak elsewhere (Beeson 1961). This is the first record of S. retorta defoliating A. mangium in Peninsular Malaysia. Thus, this studs carrie wa t y wite ou followindth h g objectives: (i) to determine the developmental biology of the insect in the laboratory, (iiexamino t ) extene eth f infestatioo t affecten no d stands d (iiian ,) to document the natural enemies associated with the moth. Such information is very pertinent for the development of an integrated pest management of the defoliator. Journal o]'TropicalForest Science 10(2): 167 -175 (1997) 169

Material methodd san s

Laboratory colony establishment

A colon . retorfawa5 f yo s established from field-collected larvae. They were reared on fresh A. mangium leaves contained in plastic containers lined with moist toilet papers. The leaves and the papers were changed daily. When the larvae reached fifte th h instar, vermiculit introduces ewa d int e containeroth e vermiculitTh . e serve a mediu s a d r pupationmfo . Three-day-old pupae were surface-sterilised witsodiu% h1 m hypochlorit transferred ean rearino t d g cage r adulsfo t emer- gence, mating and oviposition. The were given 10% honey solution and a slic ripf eo e papay s fooda a . Eggs, oviposite nettinn do g cloth linin inside gth e cagee parth f ,o t were collecte placed everan y plastin di y da c cup hatchingr sfo .

Life cycle and life table study

To determine the biological and developmental parameters of the insect, a cohoregg0 10 s f laio t d withi h wer 4 n2 e allowe hatcho dt . Larvae were reared individually in 9 cm diameter Petri dishes lined with two layers of moist filter papers younn o d . mangiumgfe A d an leaves. filtee leavee th rd Th papersan s were changed daily. Whe e larvanth e reache e fiftdth h instar, vermiculit introduces ewa d into the Petri dishes. Pupae were sexed and placed individually in plastic cups for adult emergence. Female and male moths were paired and placed in an oviposition cage. This oviposition cage consisted of a cylindrical wire mesh, 9 cm diameter X 12cm height, internally lined with netting cloth which served as oviposition witp to d sitcoverePetra h e an e th i t dis da carryind hli gcotton-pluggea d vial containin hone% 10 g y solution. These cages were kep roon i t m temperaturf eo relativd an C ° e3 humidit± 27 10%± 0 8 y. The mortality rates, developmental stages and their durations and fecundity were recorded by following the insect development from the egg stage until all the moths died. Growth increments were determine measuriny db e widte gth th f ho head capsule eacf so h instar. Fecundit mothe th calculates f yo s wa d fro totae mth l numbe eggf ro s lair femaledpe . Life table parameters were calculated according to methods described by Southwood (1978).

Field study

Field study, which included population sampling and evaluation of natural enemies associated with the defoliators, was carried out during the insect out- break from May to September 1992. Three plots consisting of 100 trees per plot were selecte randomt da boundaried an , eacf so h plot were demarcated. Routine biweekly countin larvae th f lg o populatio carries nwa d out. Each tree, abouo ttw metres high, was examined for the presence of larvae. The larvae found on the tree and on the ground under each tree were recorded. The study was terminated when no more larvae were detected. 170 Journal of Tropical Forest Science. 10(2): 167- 175 (1997)

Natural enemies associated with the defoliator were evaluated in an area outside the plot under study. About 100 larvae were sampled biweekly at random. In the laboratory the larvae were held separately in Petri dishes to evaluate survival parasitismd an . Predatio larvaf no observe s ewa d directl fielde th n y.i Predators encountered feedin larvae th n ego wer e noted.

Results and discussion

life its insect cycleThe and

newle Th y eclosed larv yellowish-brows awa coloun ni measured an r d. aboumm 0 t1 The larva underwent seven instars in a period of about 27 days (Table 1). The mature larva, dull yellowish-brow colourn ni , reache bodm m y5 d6 lengt d han 5.0 mm head capsule width. The head was brown with white lateral stripes on the vertex. The larva, very active at night, fed particularly on young leaves. At first, e larvth a chewed minut ee leaves holeth t late n i bu s, r consume leafe th yl dal parts except the veins. During the day the larva hid in leaf litter, where its body colour camouflage larva e mature dth Th . e larva pupate earthen a n di n0 cel1 t a l to 20 mm depth. The pupa, 30 mm in length, was dark brown in colour. The pupal stage laste daysd3 1 fro o .t Tablm7 showe1 life esth cycl developmentad ean l stages of the moth.

Table 1. Developmental times and sizes of head capsules of Spirama retorta

Life stages Duration Head capsule (clays) (mm)

Egg 3.0 0.00± 0 - Larva I 2.78 ±0.07 0.41 ±0.03 II 2.51 ±0.08 0.66 + 0.03 III 2.78 + 0.10 1.0 0.02+ 1 rv 2.82 + 0.15 1.54 + 0.07 V 3.88 ±0.15 2.41+0.16 VI 3.75 ±0.16 3.32 + 0.11 VII 8.07 + 0.36 4.4 0.19+ 0 Pupa 12.56±0.15 - Adult male 5.18+0.34 Adult female 6.33 ±0.55 -

e mot medius Th hwa m sized, havin d abdome re eyespon a gs a it d n nan o t forewing. Apart from those visible features, the moth exhibited wide sexual dimorphism e femaleTh . , relatively bigger tha malee nth d greyish-orang ha , e forewings with very prominent eyespot wingspaa d an s n ranging from 58.0 64.= x 4( 69.mm)o t malm e 0dard m Th .e ha k brow almoso nt t black forewings ranging from 54.0 to 66.Omm (x = 58.8mm). The eyespots on its forewings were inconspicuous. The sex ratio of male to female from field collected insects was 1 : 1.5. Journal of Tropical Forest Science 10(2): 167-175 (1997) 171

Mating, which occurre t dawnda , bega dayo ntw s after emergence. This swa followed by the female moth laying eggs one to two days after mating. In the field, the eggs were laid singly on new shoots. The egg was greyish-brown in colour, hemispherical in shape with ridges and measured about 1 mm in diameter. A female moth rearee laboratorth fecunditn a di d yha y rate rangingo t fro8 m20 307 eggs (x = 254 eggs). The average number of eggs laid daily varied from 42 firse th t n dayo , reachesubsequentld an thire y th maximus dda it n o 0 9 y f mo sixte th decline hn dayo 3 1 . Eveo dt n though some females coul days0 1 do ,t liv p eu their reproductive period lasted withi weeke egge non Th s. hatche thren di e days with hatching rates exceeding 80.0% (Figure 1).

100

+ %. hatched -so -o "rst

-20

23458 Day

Figur . Fecundite1 Spiramaf yo retorta hatchind an g percentag egge th sf eo

Life table

Less than 30% mortality occurred in the larval stage, with more than 60% individuals reaching the adult stage (Table 2). The moth had a mean net reproductive rate (Ro f 203.2o ) meaa , n generation time (Tc f 43.o ) 3 daysn a , intrinsic rate of increase (rm of 0.1 and a doubling time of 5.6 days.

Field population

Results fro e biweeklmth y sampling show thae infestatioth t n ratpesd ean t population density fluctuated over time. The extent of infestation, indicated by numbee th f treeo r s with larvae , beginninvariee th t sampline a d th fro % f go m30 g week, rose to more than 60% in the fourth week and subsequently dropped to 172 Journal of Tropical Forest Science 5 (1997 17 10(2) - 7 ) 16 : less than 10% at the end of fourteen week (Figure 2). The insect density increased from 2 larvae/tree at the beginning of the sampling week to 7 larvae/tree in the fourth week infestee . th Abouf o d% treet8 mord sha e tha larvae/tre0 n2 e during this period. After the fourth week the pest population density began to decline. By the sixteenth week no larva was found on the tree (Figure 3). Such an eruptive outbreak, according to Speight and Wainhouse (1989), could be attributed to the breakdow naturan ni l contro r rapio l d reproductio consequenpese a th s a tf no t of favourable changes in the environment. Althoug numbee hth larvaf . mangiumro A lowr tres e epe eth ,wa trees suffered defoliation rates of 20 to 30%. Such substantial damage was due to the voracious feeding relativele habith f o t y large-size long-lived dan d larvae.

Tabl . Partiae2 l life tabl f Spiramaeo retorta reare laboratore th n di y

No. No. Mortality Survival Life stages surviving dying rate rate (U (

100 (N) 2 2.00 98.00 Larva I 98 3 3.06 96.94 II 95 17 17.89 82.11 III 78 2 2.56 97.44 rv 76 1 1.32 98.68 V 75 1 1.33 98.67 VI 74 0 0.00 100.00 VII 74 0 0.00 100.00 Pupa 74 10 13.51 86.49 Adult 64

= numbe x 1 r survivin e beginninth t g a e clasag sx f g o

= numbe x d r dying durine intervaag e gth x l qx = mortality rate per age interval = ssurviva^ e intervalag rat r epe l

Natural enemies

Natural enemies evidently playe importann da t rol regulatinn ei populae gth - tion of this insect pest. The larvae and pupae were parasitised by three species f tachinidso , Carcelia sp., Exorista Blepharellad an . chalcidA sp . sp , Brachymeria sp., emerged from one tachinid pupa. Brachymeria is a common facultative hyper- parasite of tachinid (Cock 1987). The tachinids, which are generally less host specific than hymenopteran parasitoids knowe ar , parasitiso nt e other noctuid larvae suc Heliothess ha Spodopterad an (Kalshoven 1981). Figur e3 show s pooled parasitism rates in relation to host population. The parasitism rates showed a delayed density dependence (Varley et al. 1973) which contributed towards a larval mortality ranging from 5.5 43.33%o 6t rate parasitisationf eTh .o , however, varied accordin parasitoie th go t d specie timd san e (Figur Carcelia. e4) sp.,mose th t Journal of Tropical Forest Science 10(2): 167-175 (1997) 173 dominant parasitoid, was present in 5-40.5% of larvae (x = 18.0%). Exoristasp. was present in 0 - 12.5% (x = 5.0%) and Blepharella sp,. collected once during the sampling time, contributed only e parasitism1.0th f % o e tachinidTh . s were larval-pupal parasitoids. All were gregarious, with more than one adult emerging froe hosmon t (Tabl. e3)

Figur . Percentage2 f Acaciaeo mangium trees infested by Spirama retorta larvae

Figure 3. Population density and pooled parasitisation rate of Spirama retorta larvae 174

Figure 4. Percentage parasitisation of Spirama retorta larvae by three species of parasitoids

Tabl . Numbee3 parasitoif ro d progenies emerging fro mparasitisea d host

Apart from parasitoids, a number of predatory insects were recorded from the vicinite pesth tf o youtbreak e predatorTh . s were Sycanus leucomesus Walker (Hemiptera: Reduviidae), Cantheconidea furcellata (Wolff) (Hemiptera: Pentatomidae), Mallada basalis (Kimmins) (: Chrysopidae) and Vespa affinis indosinensis Perez.(: Vespidae). These predators were seen feedin sofn go t bodied , includin retorta. gS larvae impace Th . thesf o t e predator . retortaS n so population determinede b , howevero t t ye s ha ,.

Conclusion

Although Spirama retorta relativela s i y rare mot Malaysian hi t couli , d pos ereaa l threat to plantations of young A. mangium. This indigenous insect survived very well on young leaves of less than one-year-old trees. The pest outbreak lasted onl r abouyfo t fou generationro monthtw r fo r so s despit abundance eth foof eo d resource. Its disappearance might have been influenced by many factors. Natural Journal of Tropical Forest Science. 10(2): 167- 175 (1997) 175

enemies, particularl tachinie th y d parasitoids which contributed significantlo yt the mortality of 5. retorta, might be one of the primary factors in causing the population to collapse. Such ecological significance should be considered in formulatin managemenga t strateg peste th r . yfo

Acknowledgements e than W e Directokth r General, Forestry Department Peninsular Malaysiar fo , permission to conduct the study; A. Majid Abd. Rahman and Mansor Yusof of the Compensatory Plantation Unit, Forestry Department Peninsular Malaysia, and their staff for providing assistance in the conduct of the study; and J.D.Holloway, I. M. White and J. LaSalle of the International Institute of Entomology, United Kingdom, for their prompt identifications of the moth, tachinids and chalcids respectively.

References

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