Ro­dent con­trol on small-scale farms a key to food se­cu­rity

Pests can in­flict con­sid­er­able dam­age on agri­cul­ture

African Independent - - BUSINESS - LOURENS SWANEPOEL STEVEN BELMAIN

of ro­dent pests on small farms in Africa. Our re­view high­lighted sev­eral im­por­tant find­ings. We found me­dian crop losses (mid­point of re­ported losses) at­trib­uted to ro­dent pests were about 15%. This has a sig­nif­i­cant impact on grain yields and is com­pa­ra­ble to losses from ce­real stem bor­ers in Africa where much greater in­vest­ments have been made in con­trol.

But there was a big dis­crep­ancy in es­ti­mated and re­ported losses, which high­lights the im­por­tance of stan­dar­d­is­ing re­search pro­to­cols. Lit­tle re­search has been done to try and find a link be­tween ro­dent den­sity to crop impact, which lim­its the set­ting of rea­son­able man­age­ment thresh­olds on when to con­trol ro­dents based on their den­sity.

Most im­por­tantly, there is a paucity of re­search in­ves­ti­gat­ing ef­fec­tive­ness of con­trol mea­sures on ro­dent pests.

We made sev­eral rec­om­men­da­tions that we feel will im­prove the ro­bust­ness of ro­dent pest re­search. The most im­por­tant ones in­cluded the fact that re­searchers must adopt a “meta­an­a­lytic” frame­work. For ex­am­ple, they must place their study in the con­text of prior lit­er­a­ture and re­port on the ef­fect of ro­dent con­trol, par­tic­u­larly mak­ing the com­par­i­son be­tween stud­ies and strate­gies more ex­plicit.

Re­searchers and fund­ing or­gan­i­sa­tions must be en­cour­aged to es­tab­lish and fund long-term stud­ies. Once a firm foun­da­tion has been es­tab­lished on un­der­stand­ing the driv­ers of pop­u­la­tion cy­cles of the dom­i­nant ro­dent pest species, man­age­ment and com­mu­nity ecol­ogy can be suc­cess­fully de­vel­oped.

For ex­am­ple, in some African coun­tries such as Tan­za­nia, re­searchers showed that rain­fall plays an im­por­tant role in pre­dict­ing ro­dent pest out­breaks. This fa­cil­i­tated re­gional plan­ning to con­trol ro­dent pests in agri­cul­tural ar­eas.

Rain­fall pre­dicts out­breaks Re­searchers must fo­cus more on em­pir­i­cal treat­ment con­trol stud­ies that test a man­age­ment ac­tion com­pared to no man­age­ment ac­tions.

Th­ese must be done with suit­able repli­ca­tion that in­ves­ti­gates man­age­ment ac­tions on ro­dent pest pop­u­la­tions and as­so­ci­ated crop losses. For ex­am­ple, our re­cent meta-anal­y­sis showed avian preda­tors, such as barn owls, can re­duce ro­dent pests.

Last, eco­log­i­cally based ro­dent man­age­ment ac­tiv­i­ties and re­search should be car­ried out by mul­ti­dis­ci­plinary and in­ter­dis­ci­pli­nary teams. In this way re­search can be sus­tained over a longer pe­riod. – The Con­ver­sa­tion

Lourens Swanepoel is as­so­ci­ate lec­turer at the Univer­sity of Venda and Steven Belmain is pro­fes­sor of ecol­ogy at the Univer­sity of Green­wich

PIC­TURE: EPA

DEADLY PEST: As crop are en­dan­gered by rats, farm­ers in Kan­dal province, Cam­bo­dia, spend their nights catch­ing the ro­dents and ex­port­ing them to Viet­nam for food.

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