Heat, Fruit Fly Hamper Harvests in Peru and Northern Chile

Unseasonably warm weather has resulted in an unprece­dented fruit fly infes­ta­tion and low­ered an already poor har­vest out­look in north­ern Chile and south­ern Peru.

“The Mediterranean fruit fly plague is caus­ing havoc in the north of Chile and the south of Peru,” said Máximo Karl Paniagua, direc­tor of the Azapa Valley Olive Growers Association in north­ern Chile.

The inva­sive species – a close cousin of the olive fruit fly – feeds on more than 200 dif­fer­ent types of fruit and veg­eta­bles. While cit­rus and stone fruit are its most com­mon food source, females have been known to prey on olives.

Karl has seen evi­dence of Mediterranean fruit flies begin­ning to infest some olive trees in the region, with a more sig­nif­i­cant pres­ence detected in trees that bore very lit­tle fruit and were left unhar­vested.

Karl and Gianfranco Vargas, a Peruvian olive oil pro­ducer and pres­i­dent of the cul­tural asso­ci­a­tion Sudoliva, attrib­uted the spread of the Mediterranean fruit fly to the unsea­son­ably warm weather caused by El Niño.

“When El Niño devel­ops, and there are these exces­sive heat waves, the con­di­tions for the Mediterranean fruit fly and other pests to repro­duce and spread are increased,” Vargas said.

Karl added that the warmer weather increases the chance that a larger por­tion of fruit fly lar­vae will make it to adult­hood and be able to repro­duce.

The recent heat­wave expe­ri­enced in the region fur­ther ham­pered the Peruvian olive har­vest, with pro­duc­tion now expected to fall below the 700 to 1,000 tons esti­mated a few months ago, right before the har­vest began.

“The har­vest has been very bad,” Vargas said. ​“Initially, we expected to har­vest 10 per­cent of the nor­mal amount. Now, we expect to har­vest five per­cent.”

While the high tem­per­a­tures have been the lead­ing cause of the decrease in pro­duc­tion, Vargas is also wor­ried about the impact of the Mediterranean fruit fly infes­ta­tions, par­tic­u­larly on the region’s cen­te­nary trees.

“The last time a Mediterranean fruit fly attack occurred in Peru was between 1925 and 1940. In Tacna, the infes­ta­tion could not be con­trolled, and they had to cut down the olive trees,” he said. ​“That’s why in Tacna, Peru, you don’t find cen­turies-old olive trees like you can see in Arica.”

While pre­vi­ous El Niño cycles have resulted in small Mediterranean fruit fly infes­ta­tion in north­ern Chile, Karl said these were all con­trolled quickly.

He added that Chile had pre­vi­ously exe­cuted a long-term plan and arrived at the point where the fruit fly was extinct in the coun­try. Some esti­mate it will take five years to con­trol the cur­rent infes­ta­tion.

“Chile achieved the objec­tive but has since stum­bled,” he said. ​“The author­i­ties relaxed the sys­tems put in place to con­trol the Mediterranean fruit fly.”

He believes author­i­ties and farm­ers must act deci­sively before the olive trees begin to blos­som in August to avoid another poor har­vest and the fur­ther spread of the pest.

Karl also wor­ries that if the infes­ta­tion is not con­tained quickly, the Mediterranean fruit fly will spread to the coun­try’s cen­ter, where most Chilean olive oil is pro­duced.

According to Karl, Chilean author­i­ties pre­vi­ously suc­ceeded in elim­i­nat­ing the Mediterranean fruit fly by going from one olive grove to the next, apply­ing treat­ments to kill the flies.

Authorities also attempted to con­trol the infes­ta­tion by irra­di­at­ing Mediterranean fruit flies in cap­tiv­ity and releas­ing them into the val­leys. The irra­di­ated flies are ster­ile, and the idea is that they will mate with other flies to pro­duce eggs that will never hatch.

Currently, Chile can irra­di­ate 14 mil­lion flies per month, but Karl esti­mates that author­i­ties must raise this thresh­old to 30 mil­lion to man­age the infes­ta­tion.

Based on the evi­dence that he has seen, Karl believes this infes­ta­tion orig­i­nated in cit­rus and trop­i­cal fruits grown in north­ern Peru and has been spread to south­ern Peru and north­ern Chile through the ille­gal smug­gling of fruits and veg­eta­bles.

“There are more than 100 infor­mal roads that cross the bor­der into Chile, where there are no checks and goods, espe­cially fruit, come in, and this has cre­ated the prob­lem we are expe­ri­enc­ing today,” he said.

Karl believes more peo­ple guard­ing the bor­der could help crack down on smug­gling but said under­ly­ing eco­nomic con­di­tions will always make sell­ing ille­gally smug­gled Peruvian fruit in Chilean mar­kets more prof­itable.

In the mean­time, sim­i­lar erad­i­ca­tion mea­sures are also being imple­mented to elim­i­nate the Mediterranean fruit fly in south­ern Peru; Karl said these pro­grams had not been entirely suc­cess­ful, fur­ther exac­er­bat­ing the sit­u­a­tion.

“It is impor­tant for us to work closely with our Peruvian coun­ter­parts to erad­i­cate the Mediterranean fruit fly in every val­ley,” he said.

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