Uptick in Olive Fruit Fly Infestations Reported in Andalusia

As olive groves enter their most vulnerable stage of development, authorities said the number of captured flies and observed damage was significantly higher than in previous years.
Bactrocera oleae (Tephritidae)
By Máté Pálfi
Jul. 6, 2023 14:07 UTC

As olive groves in Andalusia, the world’s largest olive oil-pro­duc­ing region, enter the pit-hard­en­ing phase of their phe­no­log­i­cal devel­op­ment, the num­ber of olive fruit flies reported in groves across the autonomous com­mu­nity has spiked.

While recent rain­fall in Andalusia is unlikely to sal­vage expec­ta­tions of another poor har­vest in Spain, the lit­tle rain that did fall cre­ated ideal con­di­tions for the pro­lif­er­a­tion of the olive fruit fly, the region’s most promi­nent olive tree pest.

According to the regional government’s phy­tosan­i­tary author­i­ties, the num­ber of flies cap­tured and the amount of fruit already dam­aged indi­cate an increased pres­ence of olive fruit flies in spring 2023 com­pared to pre­vi­ous ones.

See Also:Mysterious African Insects Are Infesting Portuguese Olive Groves

However, the author­i­ties added that high tem­per­a­tures at the end of June com­bined with sus­tained efforts to treat groves has led to a recent decrease in fruit fly pop­u­la­tions and dam­age to olives.

The first dam­age caused by olive fruit flies in Andalusia was reported at the end of May.

Surveys con­ducted at the end of June by author­i­ties found that the province of Córdoba has seen the most dam­age, with 4.6 per­cent of olives sur­veyed with vis­i­ble olive fruit fly bites, a slight increase from the mid­dle of the month.

This has coin­cided with an increase in olive fruit fly plate cap­tures in the province. Authorities use plate cap­tures as a proxy for repro­duc­tive behav­ior since they use pheromones to attract the flies before they get stuck.

Meanwhile, in Jaén, the largest olive oil-pro­duc­ing province in Andalusia, author­i­ties saw a decrease in olive fruit fly bites, with a mid-month sur­vey find­ing 2.6 per­cent of fruits dam­aged and the end-of-month sur­vey show­ing 2.04 per­cent with dam­age.

However, author­i­ties also noted a sig­nif­i­cant increase in plate cap­tures over the same period indi­cat­ing olive grow­ers must remain vig­i­lant.

The province of Cadíz also demon­strated a con­cern­ing increase in olive fruit fly bites, while the province of Seville expe­ri­enced a slight decrease. Authorities had not pub­lished data from other provinces at the time of writ­ing.

However, author­i­ties said olive fruit fly cap­tures from all types of traps have been con­sid­er­ably higher in June than usual, even in areas where tra­di­tion­ally there have been fewer prob­lems with fruit fly infes­ta­tions.

Along with chem­i­cal and organic treat­ments, author­i­ties have rec­om­mended to olive grow­ers that they fos­ter appro­pri­ate envi­ron­ments for the olive fruit fly’s nat­ural preda­tors, includ­ing var­i­ous wasp and bee­tle species – Pnigalio mediter­ra­neus, Psittalia con­color, Eurytoma martel­lii, Cyrtoptyx latipes and Eupelmus uro­zonus.

Previously, Andalusian researchers pro­moted efforts to intro­duce bats to olive groves, another local olive fruit fly preda­tor.


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