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A. PRIMARY 1. SUBJECT CLASSI- Ag icU1turp FICATION U. SECONDARY I ]nnptt- sind PPAt'A 2. TITLE AND SUBTITLE affecting food supplies in developing countries: problems and needs

3. AUTHORS) Sanchez, F.F.

4. DOCUMENT DATE 5. NUMBER OF PAGES I6. ARC NUMBER 1975I 7 ARC 7.REFERENCE ORGANIZATION NAME AND ADDRESS Fish and Wildlife Service, Department of the Interior, Denver, Colorado 80225

8. SUPPLEMENTARY NOTES (Sponeoring Organizaton, Publisher&# Availabillty) (In FAO plant protection bulletin, v.23, p. 96-102)

9. ABSTRACT

A brief discussion of damage to food crops in Southeast Asia, the Pacific Islands, South Asia, Latin America, Africa, and the Near East. To boost the production of needed food, the world now Is looking to technology- Intensive agriculture. Ironically, though, these progressive agricultural practices are accompanied by an increase in the complexity and intensity of pest problems. To solve these problems and to reap the full benefits of modern agriculture, pest management systems thus must be refined even further.

10. CONTROL NUMBER 11. PRICE OF DOCUMENT PN-AAB-678

12. DESCRIPTORS .I PROJECT NUMBER

Developing countries 14. CONTRACT NUMBER Food supply PASA RA(ID)1-67 Res. Rodents Is. TYPE OF DOCUMENT

AID $90-1 (4"741 96 FAO PLANT PROTECTION BULLETIN

Rodents Affecting Food Supplies in Developing Countries: Problems and Needs" Fernando F. Sanchez, /Rodent Research Center, College, Laguna, Philippines'

Throughout much of the developing world, in the tropics, although serious rodents are major pests contributing losses to rodents to low occur in the temperate countries as well. agricultural production. While it is extremely In the rice growing regions of the world, difficult to obtain adequate quantitative data, particularly in tropical Asia, several of serious rodent damage to major crops in most rodents cause chronic losses from sowing of the developing countries has been reported, until harvest and, subsequently, in storage Estimates from various sources are available from farm to warehouse (1, 2, 4, 8, giving national loss figures, but they are 13, 14, 17). largely Other major crops subject to rodent depreda­ "guesstimates", i.e. unsound, generalized pro- tions are maize, wheat, coconut, sugar cane, jections from localized data. It is certain, how- oil palm, cocoa, and root crops (1,2, 3, 4, ever, that rodents exert a serious limitation 9, 12, 14, 15, 16). Severe food shortages have oc­ on the world food supply as well as causing curred in the past in large localized areas chronic losses to the export crops upon which in several Asian countries due to serious these countries depend for foreign exchange. population eruptions. In most of the region, Because of a general lack of reliable data this farmers are virtually helpless to control presentation aims to provide an overview rodent of depredations - not because of indifference, the ways rodents are problems contributing but because of lack of technology, knoxvldge, to low agricultural productivity in the develop- and capital. While farmers do employ various ing world. Characteristically, many of the most methods of rodent control, they lartely severely affected areas are within are the tropic ineffective and indicate a poor understanding zone. Favorable environmental conditions may of particular pest situations on the part of all have much to do with the dense rodent popuia- concerned. tions and severe damage problems occurring

Pest species I Acknowledgments: The author has bencfitted from extensive discussions with many Research Center siaff, particularlymembers of the Rodent Michael W. Fall and Species of the genus Russell R. Reidinger, Jr. of the Rallus are among the assigned to the Center. The views expressed,usAw/Psrw Team princip resent the author's however, rep- al crop pests o widespread persona! opinions in an area which rc- in the tropical and subtropical importance mains hi:hly controversial. Acknowledgement areas of the world. to the FAO Plant Protection Service, especially 11.R.is riTo due Severti s for providing the Shuyler subspecies of Rat/us raltus, scaions on the Near Eust, Olher losses vegicus, R. argentiventer, ]. nir ant problems due' to R. e.xulans and several prob!ents, and for furtherrodents, infornmauion and Olher vertebrate and a~sistance. similar species of Bandicoiaare often identified Research2Support of the author's work under the Rodent important pest species in these areas (3,4,8). as Center programnie has Philippine and United States Governments.been recceived from the Gnsernment Philippine R. rat/us and R. funds werc provided by the National Eco- nlorregicus are worldwide in nomic distribution. R. argendirenler's distribution Industry,and Development Authority, the Biureau of Plant and the University of the Philippines at Los extends Baflos. United from Thailand through the Jndo- by the States Government sunport was provided Agency for International Development and the China region, Bureau of Spor, Fisheries and Wildlife under Malaysia, Indonesia and the the project Philippines. R. exulans' range includes Burma, titledtild Theh Control onrlof7.tcrtof Vertebrate P,.sts,11ss____1S__R_____ UsDtIt'ASARACD) Thailand, Malaysia, Indonesia, the Philippines FAO PLANT PROTECTION BULLETIN 97

and the Pacific Ocean islands. spp. adequate distribution records nor adequate are widely distributed in Asia. The genus' descriptions of taxonomic relationships are range includes Sri Lanka, India, Nepal, Burma, available in many of the. areas o' concern. Thailand, China (including Taiwan province), Table I attempts to show the major rodent Indo-China, Malaysia and Indonesia. These pests limiting agricultural production in various observations must be qualified because neither regions of the developing world. In tile suc-

TABLE |. - MAJOR RODENT PESTS LIMITING AGRICULTURAL PROOUCTION IN DEVEAOPING COUNIR[ES

Crops damaged Region Species G crop:, Rice Maize Wheat Coco' Sugar fOil Root nut cane palm crops

Southeast Asia argentiventei X X x X x R. rattus x x x x x x R. exulans x x x x R. tlomanicus x x x R. losea x R. muelleri X Bandcota spp. x Xx Hystrix brachyura x Calloscurs spp. x x Sundasclurus hippurus x Mis spp. x Pacific Islands R. exulans x x x x R. raitus X X x R. norvegicus x South Asia Bandicota bengalensis x x x x x B. indica x indica X Mldlardia melada x Tatera indlica x R. rattis x x ilis spp. x Funambulus pennantl x

Latin America R. norvegicus x R. ratts x x x Sigmodon Idspidus x x x Holochllus sculreus X x Myocaster coypus x Ridpidomys coesi x Peromyscus spp. x

Africa Thryononys swinderian s x x x Praomys natialensis x x R. raittis x x Arricanthis spp. x x x x x Alstomyt sp. X x Dasylnys. incomirs x Rhabdonys pumilio x Hystrlx spp. X Xerits erythropus X Cricetoinys gamnbianus X X FulisciurU$ spp. X Jleliosciurusspp. x 98 FAO PLANT PROTECFoN BULLETIN

ceeding, discussion, an overview of rodents as arc responsible for damage to rice but q'. ar­ pests in agriculture by region is given. gentiventer apparently predominates. Although no estimates of damage arc avail­ able, rodents are marked as particularly serious Damage to crops pests of rice and sugar cane in Bu'rma.

SOUTHEAST ASIA PACIFIC ISLANDS Rodents cause serious chronic losses in the Among the Pacilic Ocean Islands coconuts region's agriculture, while serious rat outbreaks constitute a major crop and one that is heavily have occurred sporadically over wide areas of damaged bk, (11, 16). Losses from these the Philippines (13), Indonesia, Malaysia and pests in Tahiti and the Fiji Islands (15) are at Thailand. The Philippines, in the early 1950s, times quite heavy, sometimes approaching experienced the disastrous rat. outbreaks on 50 percent. Similarly heavy losses to coconuts the island of Mindanao which triggered food have been reported in New Hebrides, the shortages in the area. Repeated outbreaks Tokelaus (18), Gilbert and Ellice Islands (9). have occurred before and since then, em- Some studies suggest that coconut trees in some phasizing the continuing importance of rodents areas compensate for a portion of the damage in the well-being of the country's agriculture, by additional nut production (15). Rice is the most impoirtant crop affected in the Damage to cocoa by rats is serious in the Philippines but maize, coconut, sugar cane, Solomon Islands, Samoa, and New Hebrides. and root crops are also seriously damaged. Rats (p-incipally the Norway rat) are said Rodents cause considerable damage to Ma- to limit sugar production in Fii. Sugar c;:'e laysia's major economic crops, the most seri- is mostly grown along the coastal areas here ously affected being rice, oil paln, and cocoa. the rat problem is not acute. Four rat species are important in rice fields in Rats are also serious pests of some of the peninsular Malaysia (3, 17) and three rodent subsistence crops of the Pacific Islands. Yams, species are serious p-sts in oil palm and cocoa sweet potatoes and cassava may receive sub­ plantations. stantial damage. Indonesian agriculture, like that in much of the southeast Asian region, is beset with serious SOUTH ASIA rodent problems (4, 10). Rat outbreaks have been recorded on Java during the years of In the vast and densely populated south 1915, 1938, 1953-54, 1963-64, and 1972-73. Asian region (Pakistan, India, Sri Lanka and Serious rat damage has, likewise, occurred in Bangladesh), rodents are a major cause of food Celebes and Sumatra at various times. The losses (2, 12, 14). Estimates of from I to more major crops that are affected by rodent depreda- than 12 million tons' loss have been given for tions in Indonesia are rice, oil palm and. sugar India's yearly food grain production. Indian cane. Some damage also occurs on maize sugar cane and coconut production are also and coconut. severely hampered by rodents but estimates for In Thailand rodents arc also important these as well as for other food crops similarly agricultural pest problems (8). More than damaged are unavailable. ten species arc associated with, rice alone under Pakistan's agriculture is also plagued by field conditions. In addition to rice, rodents rodent pests, but very little information as yet damage maize, sugar cane, soybean, peanut is available. The FAO rodent control project and coconut, there lists five rodent species as major pests. Rodent damage to rice in the Republic of Rice in Bangladesh receives heavy damage South Viet-Nam is widespread and includes from two rat species. Other crops are also even the floating rice varieties. Four species damaged but losses are poorly documented. FAO PLANT PROTECTION BULLETIN 99

In Si Lanka rice may also be heavily damaged NEAR EAST by a species of ilandicota. Damage to coco­ nuts and root crops, at times, are no less I!. problems of north and serious. Africa the Near East include many which also affet nearby parts of Africa and other parts of Asia. But the depredations by species of 4An'icanthis, LATIN AMERICA Nesokia, and Taterit, among otherk must be noted. Severe damage to grain crtps, sugar Rodent pests damage the rice crops of Nica- cane, vegetables and fruits are reportd so fre­ ragua, Panama, Colombia, Surinam, and Vene- quently as to be "routine" zuela (12, 14). Severe infestation of sugar cane fields by rats are problems in most of the Carib­ bean Jslands, Mexico, Panama and Guyana. Other losses and problems due Maize and sweet potatoes are equally subject to rodents to damage as reported from Panama. This limited documentation of rodent depredations Post-harvest losses of grains, legnes, oil serves as an indication ofwhat might be expected seeds and other vgricultural products rre preva­ from other areas of tropical Latin America lent essentiall, throughout the develop/ig world. where rodents damage major food crops. These losses do not include only tboe due Disastrous to crop losses are reported repeatedly consumption of the product and its lossin weight from northeast Brazil. Argentina's crops are and volume. The increased losses -de to ir­ subjected to severe attacks by rodents. Range- retrievable spillage and rodent hoarling are land destruction by rodents is an important significant. Reduction in nutritive value, due problem in Chile. Gophers, Geomys sp., are sometimes to selective feeding, is great. Rodent a significant problem in portions of Central feeding results also in increased susceptibility America. of the stored foods to attack by insects and microorganisms. Losses resulting frzm gross contamination AFRICA by faeces and urine do not result in as much less consumption in the &veloping world as might At least be thought, but do esult fre­ 18 species of rodents have been quently in lowered sales prices. And adequate reported causing damage to various crops in -prices are one of the most important itcentives Africa (I). About half of these are established to increased production. Mice are inportant pests of the major agricultural crops of the in field crop and postharvpst losses. In the continent. Serious damage has occurred in latter, however, they are :.;insidicus pest wheat, maize, coconut, oil palm, cocoa, cassava seldom adequately "appreciated" for deir true and yams. There is no available estimate of importance. Their ability to live and breed rodent damage for Africa, but field losses are hidden within a stack of bagged grain isrespon­ often considerble. As in other areas, primitive sible for considerable damage. storage facilities may contribute significantly to Rodents are heavily involved in bsses in problems with subitantial post-harvest losses, livestock production. Yomi:g smallstzek are Though it is also true in some other areas of killed and eaten. Rats are notorious for the the world, the difficulties of rodent control in havoc they wreak in egg production. They are west Africa are complicated, indeed greatly frequently involved in disease tiansmis­ so, by the fact that some of the pest species, sion, notably leptospirosis (12). Theirinvolve­ for example, the "grass cutter" of the genus ment in human disease and its levy ai food Thr)yonoiy)s, are also important items in the production is well documented; plague, though human diet. Safety in control operations reduced in incidence, is still a problem to be assumes a new dimension, settled. 100 FAO PLANT PROTECTION BULLETIN

Other verlebrate problems (c) Encouragement of developed countrics and international organizations to provide Rodents are only one group of vertebrates expert assistance, training opportunities, which cause reductions in world food supplies, and appropriate commodity support for Most other and terrestrial vertebrate vertebrate pest management. pests only cause major reductions locally. (d) Development of graduate programmes in The depredations of monkeys must not be vertebrate pest management in the region. lightly pas.ed over, however. Even large game (e) Establishment of a regional vertebrate are d:t.ructive when. not managed pest management programme to undertake well, Perhaps thie greatest losses among these research to develop strategies, methods, animals are caused by rabbits and hares, with and materials to protect and ensure the pastures and vegetables suffering most. gains made in agricultural production. The grain eating birds and fruit eating and vampire bats are the greatest sources of agri- At this juncture, it may be opportune to em­ cultural losses among the flying animals. phasize some considerations that might prove Means have lately been developed to reduce crucial to the success of vertebrate management losses due to vampire bats. Among the grain programmes in developing countries. The va­ eating birds, the weavers and especially the riety of situations under which rodents can and genus Que.ea are important pests. FAO is do become problems complicate both the conducting resear6h leading toward control of development and implementation of control. these bird.pests in a regional project in Africa Our knowledge of the various tropical agro­ involving 13 nation,;, ecosystems is woefully inadequate. A thorough understanding of the ecology of pest spi-cies, and the varied situations where they are pests, Critical needs represents an essential need and one which will require expert assistance in most countries. There are some critical needs, the fulfilment Often we have no more than a name, of of which should alleviate the rodent and other questionable taxonomic validity, by which to vertebrate problems affecting food supplies in identify a pest rodent; the same species may be the developing world. These r:eeds were clearly known by different names in different countries. stated in the report of the 1973 FAo Panel on The identification of the species responsible for Vertebrate Pest Management in Asia and the crop damage is quite problematic because of Far East (3). While the recommendations had the peculiar habits of rodents. In the tropici reference to a particular region they could well several species may coexist in the same field be applied to the entire developing world. It area with only one or two being responsible may be noted that these recommendations for the damage. Correct identification, never­ represent no more than a restatement of the theless, is a must for the proper handling of ideas espou-ced for more than 2f years. Another particular rodent pest- situations. The general two years have passed since the FAo expert shortage of competent research workers in consultation and progress in meeting these rodent and biology is largely respon­ needs has been, to say the least, disappointing. sible for this sad state of affairs. The recommendations were: Rodent pest problems in neighbouring coun­ tries have considerable biological similarities (a) Establishment of regional coordination that make the establishment of cooperative for vertebrate pest management activities. regional research prograrmmes aimed at reducing (b) Improvement of information exchange crop losses quite attractive. However, the thrcugh print media and regular meetings of divergent cultural backgrounds, a2ricultural research and extension specialists in ver- practices, and local economics require that cach tebrate pest management. country's programmes be soundly based on FAO PLANT PROTECTION BULLETIN 101 interpretations and evaluations made in a local tised. In mono-cropping, uniform context. planting dates may be a management technique. The At the moment sustained baiting with chronic high reduction of losses in storage achievable toxicants appears to be a most promising method through exclusion of the animals from the store of control, protecting tropical agriculture from make consideration of this technique imperative. rodent depredations (5, 7). Several variations The techniques to be combined vaty from of this basic programme have been used success- problem to problem. It is easy for those from fully with several pest species in several crops. the more developed world to forget how many The problem of rodenticide resistance, well- of their practices, widely accepted, have been known in the temperate countries, should be of value in lPreventing or reducing vertebrate watched closely in the tropics as the use of pest problemis. Improved construction and chronic rodenticides becomes more intensive garbage-handling techniques are but two and routine. There is a greatly underestimated examples. need for continuing research to develop and Finally, there are the ultimate problems of test new, safe, and effective chemical control implementing programmes and bringing rodent agents. control technology and information to Because the small of the tremendous development costs farmer. This task is generally delegated for chemical to technolo,,.y, there has been minimal the extension technician who is simultaneously activity in developing new rodenticides. The responsible for all other aspects of agricultural market potential for rodenticides in agriculture production as well. Action to hire and train is quite limited because the quantities of ma- greatly increased numbers of agriculturd tech­ terials typically rqiuh -d, evL. over large areas, nicians and to provide them the means ., reach are rdatively s..ll compared to insecticides farmers must rest primarily with the developing and herbicides. The major markets continue countries themselves. However, most countries to be urban and industrial applications in de- are only beginning to recognize this problem veloped countries. Chemical companies are and we can expect that assistance with agricul­ unders andably reluctant to invest huge sums tural training programmes will be an important of money under such a situation. International activity for international and regional organiza­ organizations may be helpful in devising ways tions for the forseeable future. to break this stalemate in chemical development. Though only chronic toxicant baiting may be all that is necessary to manage some rodent Summary problems, most of these and other vertebrate pest situations will require the integration of Problems with rodent damage to food crops many techniques based upon multi-disciplinary are already worldwide and limit agricultural information. Even the proper timing ofchronic production in many areas of the developing toxicant baiting may depend upon information countries, which are characteristically food from meteorology, agronomy and sociology deficient. In the years ahead, however, those as much as that from the vertebrate pest control of us in the developing world could face a specialist (6). sur­ The use of acute toxicants in prising paradox. With the goal of increased baits seems imperative in some control pro- food production to support expanding grammes. human A recent report on trapping in- populations, we are pursuing more technology­ creases the likelihood of this age-old control intensive agriculture. But with our increasingly technique being appropriately used especially progressive agricultural practices, we are also ;vhere increased employment is also an essential. experiencing an increase in the complexity and Most other management techniques involve intensity of our pebt problems. To meet these modiftation of the environment in some way. problems, and reap the full benefits that modern These may include such measures asappropriate agriculture can supply, we must increase the crop rotation where multi-cropping is prac- sophistication of our pest management syslems. 102 FAO PLANT PROTECTION BULLETIN

The sheer magnitude of this task requires solid ened, supported and coordinated by equally national pest managementprogrammes strength- solid regional and international psgramnies.

LITERATURE CITED

1. BELLIER, L. Rodent pests of west Africa. SPAN, 1968 in Indonesia. Proceeding, Rodents as 1973 16: 28-30. Factors in Disease and Efmainic Loss, 2. BRowN, R.A. Rodent control problems in de- East-I'est Center, thmohld p. 265-272. 1970 veloping countries. Proceedings of the 11. STORER, T.r.,cd. Pacific Island raterology. Report Fourth Vertebrate Pest Conference, lVest 1962 of study madc on Ponapt and adjacent Sacratento, California, March 3-5, 1970, islands, 1955-58. Honoita, Bernice P. p. 140-143. Bishop Museum. Bulletin 225. 3. FAo. Report of the Ad hoc Panel on Vertebrate 12. TAYLOR, K.D. Rodent problems in tropical 1973 Pest Manaement in Asia and the Far East, 1972 agriculture. PANS, 18: 81-43. 20-27 September 1973, .8agk.ok, Thailand. 13. PJHIIPIrNS. UNtvmasrry. COLLEGE OF ARICUL- Rome. FAo Regular Programme No. 1972-73 TURE. Philippine Agricdturist [Rodent RAFE 14. issue], 56 (7 and 8): 4. 217-2S9. SA.CuIEZ, F.F. Vertebrate pest problems in 14. U.S. DHEART.%T-,-r OF TlE IN-Y~m . Rodents, 1974 Southeast Asia. Proceedings of the Re- 1968 bats, and birds. Damage r food supplies gional Training Seminar on Field Rat Control in the diet-deficient regions of the world. and Research, 4-15 March 1974, Manila. Denver Wildlife Research Center, Section RCR/4, 74-03-05. of AID. (Unpublished trip 5. SANCHEZ, report) F.F. Vertebrate pest management. 15. WILLIAMS, J.M. Rat damage 2j coconuts in 1975 Proceedings of the Confereuce on Plant 1974 Fiji. Part 1. Assessmeat of damage. Protection in Tropical and Sub-Tropical PANS, 20: 379-391. Areas, Manila, .4-15 Norenher 1974. 16. WILSON, E.J. The rat problem in ihe Pacific 6. SANciu Az, F.F. et a!. Annual report. College, 1968 Basin. Proceedings, Roder-s as Factors in 1972 Laguna, Rodent Research Center. Disease and Economic Lw, East-lWest 7. SANCIrz, F.F. et at. Antual report. College, Center, Houolu t, p. 9-30. 1973 Laguna, Rodent Reearch Center. 17. WooD, B.J. 1nesliations of ras in riccfields 8. SHuY.rR, H.R. Rodents as pests of rice in Thai- 1971 demonstrating en effective wntrol me:hod 1970 land. Int. Rice Conmurn Newsl., 19 (2): giving substantial yield irmrse. PANS, 20-24. 17: 180-193. 9. SMITH, F.J. Rat damage to coconuts in the Gilbert 18. WouzicK, K. Rat ecology and cetrcl in the 1968 and Ellice Islands. Proceedin,,,s, Rodents 1968 Tokclau Islands, Central lraiic. P; aeed­ es 1"actors in Disease and Econom;ic Loss, inR, Rodents as Factors ii Diseaje and East-West Center, Honolulu, p. 55-57. Economic Loss, East-West C'mfer, Ilonoitht, 10. SO KARnA, D. The ricefield rat and its control p. 73-83.