A New Invasive Pest in California

Black fig fly (Silba adipata) is a specialised pest of figs native to the Mediterranean area and first reported within the U.S. in 2021, in southern California. This fly is a menace to industrial fig manufacturing, and whereas little is understood about it, researchers at the moment are working to enhance our data of black fig fly ecology and administration. Right here, an grownup feminine black fig fly is proven depositing eggs into the ostiole of a fig fruit. (Picture by Houston Wilson, Ph.D.)

By Valeh Ebrahimi, Ph.D., Kadie Britt, Ph.D., and Houston Wilson, Ph.D.

Houston Wilson, Ph.D.

Kadie Britt, Ph.D.

Valeh Ebrahimi, Ph.D.

There may be at all times alarm when a brand new invasive pest makes its approach into the USA. A number of invasive flies have precipitated concern up to now, together with Mediterranean fruit fly (Ceratitis capitata), olive fruit fly (Bactrocera oleae), and noticed wing drosophila (Drosophila suzukii). The latest fly pest of concern in California is the black fig fly (Silba adipata), a species that completely feeds and reproduces on figs.

Black fig fly is initially from the Mediterranean area and may at the moment be discovered all through southern Europe, north Africa, and the Center East. Extra not too long ago, the black fig fly was discovered infesting figs in South Africa (2007), Mexico (2020), and now southern California (2021). California produces near 100% of the U.S. fig crop. Fortunately, the fly has not but been recovered within the Central Valley, the place a majority of business fig acreage is positioned. Following detection in Mexico, the U.S. Division of Agriculture’s Animal and Plant Well being Inspection Service positioned further restrictions on the importation of contemporary figs from Mexico to the USA.

In a new article printed in April within the open-access Journal of Built-in Pest Administration, our crew on the College of California, Riverside, and UC Cooperative Extension element present data of black fig fly biology and administration and efforts underway to raised perceive how to reply to this new invasive species.

Black fig fly (Silba adipata) is initially from the Mediterranean area and may at the moment be discovered all through southern Europe, north Africa, and the Center East. Extra not too long ago, the black fig fly was discovered infesting figs in South Africa (2007), Mexico (2020), and now southern California (2021). Proven right here is an grownup male. (Picture by Martin Hauser, Ph.D.)

Black fig fly is a small, shiny black fly with reddish eyes and brown legs, roughly 3.5 to 4.5 millimeters lengthy. Adults are recognized to feed on sap from overripe fig fruits and have proven a robust desire for the milky latex secretions coming from fruits. Females have an extended, sharp ovipositor that aids deposition of egg clusters within the ostiole of fig fruits, and so they seem to strongly choose unripe fig fruits.

Larvae emerge from eggs inside the fig and feed on inside fruit tissue, inflicting injury that may result in untimely fruit drop from bushes. When prepared, larvae make their approach out of the fruit (inflicting a attribute small exit gap), drop to the soil, and pupate. Pupae are the overwintering stage and in spring they emerge, mate, and start to assault figs. Black fig fly is multivoltine and may have between 4 and 6 generations per 12 months below a Mediterranean local weather.

Grownup black fig fly populations might be monitored utilizing a McPhail-type entice baited with both torula yeast or a mix of two p.c ammonium sulfate and hexanol. Following native stories of infestation in southern California, traps have been deployed in just a few places in Ventura and Santa Barbara counties in 2021. Each lures have been profitable at attracting and capturing grownup black fig fly.

Black fig fly (Silba adipata) larvae emerge from eggs inside the fig and feed on inside fruit tissue, inflicting injury that may result in untimely fruit drop from bushes. When prepared, larvae make their approach out of the fruit, drop to the soil, and pupate. (Picture by Houston Wilson, Ph.D.)

Black fig fly (Silba adipata) larvae emerge from eggs inside the fig and feed on inside fruit tissue, inflicting injury that may result in untimely fruit drop from bushes. When prepared, larvae make their approach out of the fruit, drop to the soil, and pupate. (Picture by Houston Wilson, Ph.D.)

Black fig fly (Silba adipata) larvae emerge from eggs inside the fig and feed on inside fruit tissue, inflicting injury that may result in untimely fruit drop from bushes. When prepared, larvae make their approach out of the fruit (inflicting a attribute small exit gap, proven right here), drop to the soil, and pupate. (Picture by Houston Wilson, Ph.D.)

Grownup black fig fly (Silba adipata) populations might be monitored utilizing a McPhail-type entice (proven right here) baited with both torula yeast or a mix of two p.c ammonium sulfate and hexanol. (Picture courtesy of College of California Agriculture and Pure Assets)

There may be little or no present info on pure enemies. One research reported parasitization of black fig fly pupae by the wasp Pachycrepoideus vindemmiae, however implications for organic management in industrial orchards stays unclear, as this can be a generalist parasitoid that assaults greater than 60 totally different species throughout Europe and North America.

For now, and within the close to future, orchard sanitation is crucial and any dropped fruits must be eliminated and destroyed as a consequence of potential larval infestation. At present, suggestions for chemical management are very restricted. Even so, larvae are the damaging stage, and focusing on them might be robust as a consequence of safety from the outer masking of the fig fruit. Insecticide baits could have larger administration potential however haven’t been evaluated but in California.

Data concerning common biology and phenology of black fig fly in California is at the moment unclear, together with complete variety of generations per 12 months, present geographic distribution and potential for unfold, minimal and most temperature thresholds, and degree-day necessities throughout life phases. As knowledge are generated to deal with these unknowns, we may have the power to raised predict the potential unfold of this pest in California, in addition to timing of key phenological occasions. Extra broadly, these knowledge can be utilized to find out a extra complete threat evaluation for the main fig manufacturing areas within the Central Valley, in addition to areas the place black fig fly has already established. As an example, one key purpose could be to estimate the timing of grownup emergence and doable infestation occasions relative to improvement and availability of latest fig fruits.

Over the subsequent 12 months, knowledge on the developmental biology of black fig fly can be generated after which used to mannequin the potential geographic vary of this invasive pest. Moreover, we plan to guage numerous entice and lure sorts to optimize monitoring protocols, totally delineate the present unfold of this pest, and consider the efficacy of chemical controls, together with supplies authorised for natural manufacturing.

In late summer season of 2021, we visited fig growers in southern California and noticed firsthand the injury that black fig fly could cause. This pest is especially difficult as a result of it’s not often evident the place a feminine has laid eggs or the place a larva is current inside the fig. By the point infestation is obvious, fig fruits have often already fallen from the tree. As such, bettering monitoring protocols is one in all our highest priorities. Black fig fly will proceed to be a difficulty for fig growers in southern California for the foreseeable future, however analysis is underway to deal with among the most urgent questions.

Valeh Ebrahimi, Ph.D., and Kadie E. Britt, Ph.D., are postdoctoral students within the lab of Houston Wilson, Ph.D., assistant cooperative extension specialist within the Division of Entomology on the College of California, Riverside. Valeh is positioned on the UC Riverside campus and Kadie and Houston are positioned off campus on the Kearney Agricultural Analysis and Extension Heart in Parlier, California. Twitter: @EbrahimiValeh, @kadiehemp, and @treecrops. E mail: valehe@ucr.edu, kadieb@ucr.edu, and houston.wilson@ucr.edu.

Associated