Armored bush crickets (Acanthoplus spp.) are sporadic pests on cereals in southern Africa. The performance of different IPM components on pearl millet [Pennisetum glaucum] in Namibia and sorghum in Namibia and Zambia is reported, based on on-farm participatory trials

Chisi, M

Ekandjo, S

Minja, E

Musonda, E

Mwandila, D

Wohlleber, B

ICRISAT Open Access Repository

corneousness contributes towards resistance to grainmolds in white-grained genotypes. The iodine vapor ab-sorption test described facilitates visual assessment ofendosperm corneousness in sorghum.ReferencesGlueck, J.A. and Rooney, L.W. 1980. Chemistry ofgrain in relation to mold resistance. Pages 119-140 inSorghum diseases — a world review. Proceedings of theInternational Symposium on Sorghum Diseases, 11-15Dec 1978. ICRISAT, Hyderabad, Patancheru 502 324,Andhra Pradesh, India: International Crops Research In-stitute for Semi-Arid Tropics.Rooney, L.W. and Miller, F.R. 1982. Variation in thestructure and kernel characteristics of sorghum. Pages143-162 in Proceedings of the International Symposiumon Sorghum Grain Quality, 28-31 Oct 1981. ICRISAT,Hyderabad, Patancheru 502 324, Andhra Pradesh, India:International Crops Research Institute for Semi-AridTropics.Somani, R.B. and Indira, S. 2000. Relationship betweenwater imbibition and grain hardness to grain mold resis-tance in sorghum. Indian Phytopathology 53: 42-44.A New Method of Inoculating GrainSorghum Spikelets with SorghumMidge Eggs by Water InjectionA T Hardy and B A Franzmann (Department ofPrimary Industries, PO Box 102, Toowoomba, Queens-land, 4350, Australia)A new method of infesting flowering sorghum [Sorghumbicolor (L.) Moench] spikelets for midge (Stenodiplosissorghicola Coquillett) resistance screening work has beendeveloped. It uses midge eggs injected into individualsorghum spikelets with an adjustable volume micro-pi-pette. This method was developed to overcome the incon-sistent egg lay achieved across a range of midge-resistantsorghum lines.In the new method, a small volume of water containinga set number of eggs is injected between the glumes ofeach spikelet. After injection the water evaporates leav-ing the eggs attached to the inside structures of the spike-let. A variety of egg densities were tested, ranging fromexactly 2 eggs per spikelet up to 4—6 eggs per spikelet.Not all eggs remained within each spikelet. One trial thatinvolved infecting exactly 2 eggs per spikelet over a num-ber of lines with spikelets of different size and shape re-sulted in an average of 0.8-1.1 eggs per spikelet, and50-75% egg infestation of spikelets with eggs. Similarlyinjecting 4-6 eggs per spikelet resulted in 2-3 eggs perspikelet, and 80-95% infestation of spikelets with eggs.In all the trials, most of the eggs were found positioned onthe inside of the glumes regardless of spikelet dimen-sions, with the remaining eggs on other structures withinthe spikelet, or on the outside of the glumes.The possibility of using eggs stored in water for pro-longed periods was tested in a laboratory bioassay by thewater injection method. Freshly laid midge eggs werestored in water from 0- 21 days in the refrigerator at 4°C.The results indicated that eggs stored in water for 4 h were significantly more viable (80%) hatch) than eggsstored for 1-7 days in the refrigerator (40-65% hatch).No viable eggs were retrieved after 14 or 21 days.Using midge eggs stored in water prior to injectioninto sorghum spikelets appears to be a useful and practi-cal technique for midge-resistance studies. This tech-nique needs to be improved for precise and consistent egginsertion into each spikelet across a range of sorghumlines. It could then be used to conduct a range of tests forantibiosis and tolerance mechanisms for resistance to sor-ghum midge.Integrated Pest Management ( I P M )Components for Control of ArmoredBush Cricket on Pearl Millet andSorghum in Farmers' Fields inNamibia and ZambiaE Minja1, B Wohlleber2, S Ekandjo3, M Chisi4,E Musonda5, and D Mwandi la6( 1 . International Crops Research Institute for the Semi-Ar id Tropics ( ICRISAT), P O Box 1096, L i longwe,Malawi ; 2. Ministry of Agriculture, Water and Rural De-velopment, Private Bag 13184, Windhoek, Namibia; 3.Ongwediva Agricultural Development Centre, PrivateBag 5556, Oshakati, Namibia; 4. Golden Valley ResearchTrust, P O Box 54, Fringi la, Zambia; 5. Mount MakuluCentral Research Station, Private Bag, Chilanga 7, Zam-bia; 6. Lusitu Agricultural Research Off ice, P O Box 97,Siavonga, Zambia)Armored bush crickets (Acanthoplus spp) are sporadicbut economically important pests of cereals in severalcountries in southern Africa. In outbreak seasons,ISMN 40, 1999 47A. discoidalis J. Irish causes on average 30% grain yieldloss on pearl millet in Namibia (Wohlleber 1996), whileA. speiseri Brancsik causes up to 60% yield losses on sor-ghum in the Gwembe valley of southern Zambia(Musonda and Leuschner 1990). In both countries, and inneighboring Zimbabwe, Botswana, Mozambique,Malawi, and Tanzania, the pest is a threat to poor farm-ers' livelihoods both in outbreak seasons and also inyears of low pest population density.Before the 1990s, the biology of armored bush crick-ets was very poorly understood. Recently however, thetaxonomy of the group has been improved by a revisionof southern African genera (Irish 1992), whilst Mbata(1992) and Musonda and Leuschner (1990) have ex-tended ecological knowledge of these pests. Musondaand Leuschner (1990), Leuschner (unpublished), and es-pecially Wohlleber (1996) and Wohlleber et al. (1996)have started to develop management strategies. Thesestrategies include; use of short-duration varieties, cleanweeding within and around fields, use of insecticide baitsalong field borders, selective spraying on nearby bushes,and egg search and collection. Farmers in Namibia andZambia have developed their own cultural practices thatinclude early sowing, clean weeding, field bordertrenches, early harvesting, stooking pearl millet, andhand-picking crickets in Namibia, and lower leaf strip-ping on sorghum in Zambia.The strategies were tested individually in Namibia andZambia and most of them were found effective to somedegree (Musonda and Leuschner 1990; Wohlleber 1996).To ensure sustainability however, these strategies werecombined to form an integrated pest management (IPM)strategy) and tested for the first season in 1997/98. Di f -ferent component combinations were tested and verifiedin on-farm trials in Namibia and Zambia. The combina-tions were:Namibia. Early sowing and hand-picking were commonto most farmers;1. Mixed local cultivars of pearl millet and sorghum;clean weeding2. Short-duration pearl millet variety Okashana 1 mixedwith local cultivar Karango; clean weeding; selectivebush spraying; field edge baiting3. Mixed local cultivars of pearl millet and sorghum;clean weeding; predatory birds4. Okashana 1 mixed with local pearl millet cultivar andcowpea [Vigna unguiculata (L.) Walp.]; clean weed-ing; kraal manure application5. Okashana 1 mixed with local pearl millet, sorghum,cowpea and melons (Cucumis and Citrullus spp);early sowing at field borders, late sowing in themiddle of fields; clean weeding; trench preparationalong bushy field borders6. Okashana 1 mixed with cowpea and melons; kraalmanure application; clean weeding; early harvesting,and stooking7. Mixed local cultivars of pearl millet and sorghum;kraal manure application; clean weeding; early har-vesting and stookingZambia. Early sowing, sole crop of short-duration sor-ghum variety Kuyuma, mixed cropping of long-durationvariety Longo, were common to all on-farm participatingfarmers;1. Early-sown Kuyuma; clean weeding; lower leaf strip-ping; and hand-picking2. Early-sown Kuyuma and Longo; trench preparationfor Kuyuma field; clean weeding within and aroundfields; hand-picking3. Early-sown Kuyuma; clean weeding; hand-picking4. Early-sown Kuyuma; weeding once at 4 weeks aftergermination.5. Local cultivar Longo mixed with cowpea, mungbeans [Vigna radiata (L.) Wilczek], and melonsIn Namibia and Zambia, farmers' fields (0.25-0.5 ha)were used as replicates. In cases where farmers own largefields and agreed to have different combinations, farmersacted as blocks. Crickets were counted at crop maturity/harvest on 5-m x 5-m sub-plots marked out randomly ineach field. Crop maturity/harvest period coincides withthe highest population peak for the crickets. Similar butseparate sub-plots were used for damage and yield as-sessments.The estimated cricket population density in Namibiaand Zambia during the 1997/98 season was 25-30% thatof a normal outbreak season. The low pest populationdensities were an outcome of low and unevenly distrib-uted rainfall in Namibia (total 250-350 mm) and Zambia(total 400-500 mm). Grain yield loss was estimated at5-15% on pearl millet in Namibia and 10-40% on sor-ghum in Zambia. Tables 1 and 2 show the cricket popula-tion density, panicle damage, and estimated grain yieldsunder different component combinations tested inNamibia and Zambia.In Zambia the long-duration sorghum cultivar Longosuffered severely from terminal drought that resulted inno grain being produced. Despite low and poorly distrib-uted rainfall for crop establishment, the improved short-duration pearl millet variety Okashana 1 and improvedshort-duration sorghum variety Kuyuma performed wellin terms of the grain yields that farmers harvested at theend of the season. Similarly, most of the components es-pecially early sowing, use of kraal manure, weeding,48 ISMN 40, 1999T a b l e 1 . P e r f o r m a n c e o f I P M components f o r cont ro l o f a r m o r e d c r icke t o n p e a r l m i l l e t , N a m i b i a , 1997 /98 .C r o p p i n g pat te rnM i x e d loca l cu l t i va r s o fpear l m i l l e t and s o r g h u mOkashana 1 m i x e d w i t hloca l m i l l e t K a r a n g oM i x e d loca l cu l t i va r s o fpear l m i l l e t and s o r g h u mOkashana 1 m i x e d w i t hloca l s o r g h u m and c o w p e aOkashana 1 m i x e d w i t hloca l m i l l e t , s o r g h u m ,c o w p e a , m e l o n sOkashana 1 m i x e d w i t hc o w p e a and m e l o n sM i x e d loca l cu l t i va r so f pear l m i l l e t and s o r g h u mM e a nS EI P M c o m p o n e n t c o m b i n a t i o n sE a r l y s o w i n g1, c lean w e e d i n g ,h a n d - p i c k i n g1C l e a n w e e d i n g , Se lec t ive bushs p r a y i n g , f i e l d edge ba i t i ngC l e a n w e e d i n g , p redatory b i rdsC l e a n w e e d i n gEa r l y s o w i n g a long f i e l d bordersand s o w i n g i n m i d d l e o ff i e lds , t rench a long bushy bordersC l e a n w e e d i n g , k raa l manu re ,Ea r l y ha rves t i ng and s t o o k i n gC lean w e e d i n g , k raa l manu re ,Ea r l y ha rves t ing and s t o o k i n gCr i cke t s atat harvest( n u m b e r s )5.23.15.35 .43.05.12 2 . 47.1± 1.5D a m a g e dpan ic les(%)20 .415.318.29 . 04 .34 .14.210.8± 2.6Es t ima tedg ra in y i e l d(t ha- 1)0.50.80.50 . 70 .91.30 .60.8± 0.31. Pract ices c o m m o n to a l l f a rmers in no r t he rn N a m i b i aT a b l e 2 . P e r f o r m a n c e o f I P M components f o r cont ro l o f a r m o r e d c r icke t o n s o r g h u m , Z a m b i a , 1 9 9 7 / 9 8 .C r o p p i n g pat ternSole c rop sho r t -du ra t i onvar ie ty K u y u m aSole c rop K u y u m aSole c rop K u y u m aSole c rop K u y u m aL o c a l l o n g - d u r a t i o n c u l t i v a rL o n g o m i x e d w i t h c o w p e a ,me lons and m u n g beansM e a nS EI P M c o m p o n e n t c o m b i n a t i o n sE a r l y s o w i n g1, c leanw e e d i n g , lea f s t r i pp i ng , h a n d - p i c k i n g2Clean w e e d i n g , t rench a roundf i e l d , h a n d - p i c k i n g2C l e a n w e e d i n g , h a n d - p i c k i n g2One w e e d i n g w i t h i n f i e l d4 weeks af ter g e r m i n a t i o nC l e a n w e e d i n gCr i cke ts atat harvest(numbers )2.22.13.19.34 .34.2± 1.1D a m a g e dpan ic les( % )5.44 .55.333 .2N o pan ic lesma tu red9.7± 2.9Es t ima tedgra in y i e l d(t ha-1)0 .70.80.50.3N o y i e l d0.5± 0.21 . E a r l y s o w i n g was p rac t i ced by a l l p a r t i c i p a t i n g fa rmers2 . Pract ice i m p o r t e d f r o m N a m i b i a and accepted by some fa rmers i n Z a m b i aISMN 40, 1999 49hand-picking, early harvesting, and stooking were all ad-vantageous to crop performance.The pest population estimates were similar forNamibia and Zambia. However, damage was slightlyhigher in Zambia than in Namibia due to the fact that allfarmers' families in Namibia have a traditional commit-ment to hand-picking the crickets daily from their fieldsand crushing them or suffocating them in polythene bagsbefore burning them. This tradition is lacking in Zambia.Some of the extension personnel in Namibia have alsobeen trained to use a forecasting tool (a cricket egg-hatching trap) developed by Wohlleber et al. (1996) tomonitor cricket egg hatch after the first heavy rains. Thisinformation enables the extension staff to inform farmersin time to initiate management practices. The Sorghumand Millets Improvement Program (SMIP) facilitated ex-change visits of one technical staff directly involved withthe farmers in each of Namibia and Zambia. These visitswere in anticipation that the exchange of technologiesbetween the two countries wi l l continue to develop.During the course of field work in the 1997/98 season,a few Zambian farmers were convinced and accepted thathand-picking crickets from their fields was helpful in re-ducing panicle damage. According to the farmers in Zam-bia, hand-picking did not involve extra costs from thembecause it was carried out at the same time as farmerswere scaring birds from their fields. The search for addi-tional management components including populationforecasting and the use of semio-chemicals (chemicalsmells or cues, e.g., pheromones) and bio-pesticides tocomplement the above practices is anticipated in the nearfuture. The technologies were only tested and verifiedwith a few farmers, particularly in Zambia. There is a need for follow-up verification with more farmers for ef-fective diffusion and spillover to neighboring countries.ReferencesIrish, J. 1992. The Hetrodinae (Orthoptera: Ensifera:Bradyporidae) of southern Africa: systematics and phy-logeny. Navorsinge van die Nasionale MuseumBloemfontein, Natural Science 8(8):393-434.Mbata, K.J. 1992. The biology and host plant specificityof Acanthoplus speiseri Brancsik (Orthoptera:Tettigoniidae: Hetrodinae), a pest of grain crops. Journalof the Entomological Society of South Africa55(1):99-106.Musonda, E. and Leuschner, K. 1990. Biology and con-trol of armored cricket. Pages 230-243 in Proceedings ofthe Sixth Workshop on Sorghum and Millets forSouthern Africa, 18-22 September 1989, Bulawayo,Zimbabwe. PO Box 776, Bulawayo, Zimbabwe: SADC/ICRISAT Sorghum and Millets Improvement Program.Wohlleber, B. 1996. First results of research on the ar-mored bush cricket (Acanthoplus discoidalis) on pearlmillet in Namibia: population dynamics, biology, andcontrol. Pages 163-172 in Drought-tolerant crops forsouthern Africa; proceedings of the SADC/ICRISAT Re-gional Sorghum and Pearl Mil let Workshop, 25-29 July1994, Gaborone, Botswana (Leuschner, K. and Manthe,C. S. eds.) Patancheru, 502 324, Andhra Pradesh, India:International Crops Research Institute for the Semi-AridTropics. 376 pp.Wohlleber, B., Schmutterer, H., Leuschner, K., andEkandjo, S.T. 1996. Armored bush cricket (Acanthoplusdiscoidalis) — population dynamics, biology, and con-trol on pearl millet. Pest Control Workshop, September1996, Ministry of Agriculture, Water and Rural Develop-ment, Windhoek, Namibia.Evaluation of Sorghum Genotypes forRelative Resistance to Corn LeafAphid, Rhopalsiphum maidis S P Singh and R P S Grewal (Chaudhary Charan Singh(CCS) Haryana Agricul tural University, Hisar 125 004,Haryana, India)The corn leaf aphid, Rhopalsiphum maidis (Fitch.), was first reported in Haryana on sorghum by Singh (1985).For the last few years corn leaf aphid attacks on maturingsorghum have been observed to be increasing during Sep-tember and October when they reduce grain and greenfodder yields and the quality of the fodder. The aphidsinitially appear in patches in the field and are generallyfound deep in the whorl of middle leaflets, and on theundersides of leaves. Even stems and panicles can beseen to be infested. Both nymphs and adults suck theplant sap and cause yellowish mottling of the leaves.Consequently marginal leaf necrosis appears. The aphidsproduce an abundance of honeydew on which moldsgrow.This pest is becoming a regular problem on sorghumat the harvesting stage, a time when chemical control isvery diff icult and uneconomic. Thus, sorghum genotypeswith resistance to aphids would be an extremely valuableway to control this pest. The present investigations wereundertaken to identify the sorghum genotypes least sus-ceptible to corn leaf aphid.50 ISMN 40, 1999

Integrated Pest Management (IPM) Components for Control of Armored Bush Cricket on Pearl Millet and Sorghum in Farmers' Fields in Namibia and Zambia

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Integrated Pest Management (IPM) Components for Control of Armored Bush Cricket on Pearl Millet and Sorghum in Farmers' Fields in Namibia and Zambia

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