Journal of Tropical Forest Science 10(4): 438 - 455 (1998) INSECT PEST FORESF SO T TREE SEEDS: THEIR ECONOMIC IMPACT AND CONTROL MEASURES N. Kulkarni & K.C. Joshi Forest Entomology Division, Tropical Forest Research Institute, Jabalpur - 482 021, India Received January 1996___________________ _________________ _________ KULKARNI &. ,N JOSHI , K.C. 1998. Insect pest foresf so t tree seeds: their economic impact and control measures. The quality of seed production and seed viability are affecte insecy b d t infestation tren o s e stand durind san g storage. Infestation causes considerable economic losses e majoTh . r grou f insecpo t pests damaging flowers, fruits and seeds of various hosts in India and abroad are given in the present paper. Possible management practices are also discussed. Keywords: Seed insect pests - biological control - macro-organisms-pathogens - Bacillus thuringiensis - natura l enemies KULKARNI, N. &JOSHI, K.C. 1998. Seranggaperosakbijibenihpokokhutan: kesan ekonomi dan cara mengawalnya. Mutu pengeluaran biji benih dan keupayaan biji benih dipengaruhi oleh pengerumunan serangga pada dirian pokok dan juga semasa penyimpanan. Pengerumuna i menyebabkain n n kerugian dari segi ekonomi. Kumpulan serangga perosak daripada beberapa perumah yang paling banyak memusnahkan bunga, buah dan biji benih di India dan di luar negara telah dinyatakan dalam kertas kerja baru-baru ini. Amalan pengurusan yang perlu juga turut dibincangkan. Introduction The problem of seed destruction is increasing due to our increasing reliance on seed sources for the production of seedlings or for trees of known genetic characteristic reforestation si reclamatiod nan n programmes southern I . n United States alone, trees are cultivated as seed sources over relatively large areas of acre0 abou00 s0 (Goye1 t Nacho& r d 1976) flowerse Th . , fruits, seed conesd san , being rich food sources, are vulnerable to insect pests and diseases. Insects that fee then do m often cause seed crop failure (Barbos Wagnea& r 1989thusd an ) , exert an adverse impact on natural and artificial reforestation. Regeneration failure, especiall tean yi k (Tectona grandis)l (Shoreasa d an robusta) Indin i d aan conifer othen i s r countrie attributee b factorsn o sca tw do t , firstly heave ,th y insect attack in the natural stands at the time of inflorescence and seed formation, and secondly, insect attack on the ground after seed shedding (Chatterjee & Thapa 1970, Khatu Chakrabarta& i 1990). 438 9 43 Journal of Tropical Forest Science 5 (1998 45 10(4) - 8 ) 43 : Although there are many reports on forest seed pests of broad-leaved and coniferous tree species (Beeson 1941, Pruthi & Singh 1950, Johnson & Heikkenen 1958, Mathur el al 1958, Johnson 1963, Johnson & Hedlin 1967, DeBarr & Kormanik 1975, Sing Bhandarh& i 1987,1988,Josh 1990. al t ie , Patha l 1995)a t ke , e identificatioth pestsw ne ,f o nreviewin lossee gth s cause they db d thei man r management practices undertakeneee b o dt n from tim timeo et . Insect pests of fruit/cone/seeds insece Th t orders, associated with destructio e mosth f to conef no seedd e san ar s Coleoptera (beetles and weevils), Lepidoptera, mainly the families Pyralidae (cone worms), Tortricidae (seed worms), Olethreutidae (cone moth cond san e borers), Hymenoptera, primarily the seed chalcids (Torymidae), Hemiptera and Diptera (Cecidomyiidae). The damage caused by insect pests can be categorised into seed damage in standing trees and damage in storage conditions (Singh & Bhandari 1986). A list of some major insect pests damaging flowers, fruits, cones and seeds of conifers, broad-leaved (leguminous and non-leguminous) hosts in India (Beeson 1941, Mathur et al. 1958, Singh & Bhandari 1987, 1988) and other countries (Johnso Heikkene& n n 1958,Johnse Hedli& n n 1967, DeBarr & Kormanik 1975, Goye Nachor& d 1976 gives i ) Tabln i . e1 Mathur et al. (1958) has listed 558 insect pests damaging flowers, seeds and fruits on 363 plant species in India. The Lepidoptera have the greatest species richness amon cone/seee gth d pests (Mathur 1958,Turgeo . etal n 1994). etal e Th . cone genue wormth f so sDioryctria (Pyralidae e majoar ) r seed pest f Cedruso s deodara, firs, pines in India and abroad (Singh & Bhandari 1986). Hedlin et al. (1980) described 21 species from the United States, Canada and Mexico. Cone worms begin feedin conee th n gsi only when thematuree ar y d larvae. Conse- quently, a distinct larval entrance hole, often surrounded by silk, is visible on attacked cones larvae Th . e pupat a pupatio n i e n chambe conen i rleav d an s e the cavity after adult emergence, resulting in cone mortality and complete seed loss. Similar reports are available on Cedrus deodara and chilgoza pines (Pinus girardiana) Indin i a (Sing Bhandar& h i 1986) f greawhico e t har commercia l importance. Cone moths of the genus Barbara (Tortricidae) are also major seed and cone insects. Among them, Barbara colfaxiana Kear, is a particularly important pest of Douglas fir. Seed worms like Cydia spp. (Laspeyresia spp.) feed almost exclusively on seeds (Coulson & Witter 1984). The coleopteran seed pests are limited to four families - Scolytidae (cone beetles), Curculionidae (cone weevils), Bruchidae and Cerambycidae. Damage cause Conophthorusy db speciesubstantiae b n sca commercialln i l y valuable pine species. Successful colonisation of the second-year cones ensures the death of conee th d seedsthusl lose al an s f th s,o . Infested easile coneb n ys ca recognised by resin accumulatio entrance th t na e hole discoloured an , reduced dan d sizf eo cones. Out of 11 species of Conophthorus that occur in North America, 3 are frequently serious pests, i.e. the white pine cone beetle, C. coriperday (Schwarz.), 440 Journal of Tropical Forest Science 10(4): 438 - 455 (1998) pind re ee conth e beetle resinosae. C , ponderosd an (Hopkins)d re e ath pind ean , cone beetle ponderosae. C , (Hopkins) (Coulso Witten& r 1984)e n mosth I . f o t cone beetles particularld an , y amon genue gth s Conopthorus, adults after leaving their overwintering hybernacula, go through a sequence of behaviours leading to brood establishments, which include initial penetration, construction, and filling plugginpocketg e th eg axia e f d o th an sf lp g o tunnelu entrance Th . e tunnel into e conth constructes ei y femaledb s which prepare bling pocketeg d s after reaching the center of the axis. In C. ponderosae, on ponderosa pine the female usually girdle axie th ss nea basee th r , thereby severin conductive gth e tissued an s causing early cone death. Girdling appears to be a prerequisite for brood development (Kinzer 1976). Cone weevils greaf o e t,b thougheconomit no y ,ma c importance causo d t e,ye substantial damag deciduouo t e s tree species. Curculio d Conotrachelusan spp. breeacorne th larg a n df i s o e numbe oakf ro , butternuts, walnuts, hickoried san filberts (Barbosa & Wagner 1989). The Quercus seed weevil, Sitophilus glandium (Marshall) (Curculionidae), attacks young developing acorns of Quercus semicarpifolia, Q glauca, Q. lanuginosa and Q leucotrichopora. The young grubs of this weevil mine throughout the tissues, but older grubs work at the base, leaving the distal part untouched. Sometimes the whole crop is destroyed resultin n i poog r regeneratio f oako n s (Sing Bhandar& h i 1986)e Th . Cerambycids, on the other hand, lay eggs singly between scales of fully grown green cones. The young grubs bore into cones, feed on all tissues including seed and cause damage up to 40%. They are known to cause comparatively lesser damage than other insect orders. Bruchid vere sar y serious pest seedsf so , especiall Acaciaf o y (Southgate 1983, Dwivedi 1993 Albiziad an ) spp. (Mathu . 1958,Joshal t re . 1990al t storage in i ) s ea well as to pods on trees. In India, eight species of bruchids, viz. Bruchidius pisorum (Linn.) . pygoquadrimaculatusB , sp. saundersiB , (Jakel.) . schrodei,B , . uberatusB (Fahr.),Bruchus bilineatopygus (Pic.), B. sparsemaculatus(Pic.) and Caryedon gonagra (Fabr.), have been reported to damage Albizia seeds (Singh et al. 1983, Singh & Bhandari 1986,Josh thesef 1990). o al t t . bilineatopygusie B , Ou . causes abou% t80 damag procera. seedA e lebbek. th d A f o esan t o (Josh 1990. al t e i , Joshi 1992). Light brown coloured, small, active, about 4.0 - 4.5 mm long weevils of B. bilineatopygus lay oval, light-yellowish eggs on the young pods of A. lebbek, in the first week of September. The small grubs enter the fleshy pods by the middle of September, evidently visible by the oozing of a small quantity of gummy fluid from bored pod. The grubs reach the young seeds by the end of the month where they feed on them and reach to a maximum length of about 5 mm inside the seeds. These grubs are greenish-yellow in colour. They turn into about 4 mm long yellow- coloured pupae by the end of October. These weevils after emerging from the seed pods again oviposit the eggs of the second generation on either side of the seed pods of A. lebbek and A. procera. These eggs hatch to grubs, which enter inside the seed develoo st p into pupa thed ean n ultimatel weevilso yt . These weevils after emerging fro seede mth s again oviposi storee t eggth n dso seed whicn si h they continue to breed. The pest has more than five generations in a year (Joshi 1992). Journal of Tropical Forest Science 10(4): 438 - 455 (1998) 441 Lamprey et al. (1974) observed Bruchidius spadicousFabr. to be infesting seeds of Acacia tortilis spirocarpaX Tanzanian i sais i t dI . that passag seedf eo sf o throug t gu e hth browsing mammals kills the larval insect and renders the seeds viable with higher germination rate (Lamprey et al.