Heat, Fruit Fly Hamper Harvests in Peru and Northern Chile

Unseasonably warm weather has created the conditions for the Mediterranean fruit fly to proliferate. Smuggling may have furthered its spread in Chile.
Mediterranean Fruit Fly (Ceratitis capitata}
By Daniel Dawson
Apr. 28, 2024 17:11 UTC

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.

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.- Gianfranco Vargas, pres­i­dent, Sudoliva

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.

See Also:Olive Lace Bug Adds to Harvest Woes for Australian Farmers

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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