Herbivores associated with Arundo donax in California.

Abstract

The Old World grass, Arundo donax L. (giant reed), is a serious invader of California riparian areas, and its purported ecosystem impacts led to its consideration as a target for biological control development. However, the herbivore complex in the Arundo adventive range has not been characterized, so there is little information regarding insects that may hinder biological control efforts by interfering with the release of new agents or that could be promoted as augmentative biological control agents if they have a substantial impact on the target weed. Here we report the results of surveys in California, with emphasis on three presumably non-indigenous insects that inflict significant damage to the host. One is a shoot-boring wasp, Tetramesa romana (Walker) (Hymenoptera: Eurytomidae), with a range limited to southern California and that damages shoots generally less than 1 cm in diameter. A shoot fly, Cryptonevra sp., is also associated with shoot damage and often mortality of secondary stems. A third herbivore, the aphid Melanaphis donacis (Passerini), is widespread in the southern and central parts of the state but has less apparent impact to the host. T. romana and Cryptonevra sp. are currently candidates for biological control development and introduction from overseas locations. Their established presence in California suggests that efforts could be revised to focus on documentation of host ranges and impacts under field rather than in quarantine conditions, in anticipation of future re distribution in North America.

Testing the Enemy Release Hypothesis on tall-statured grasses in South Africa, using Arundo donax, Phragmites australis, and Phragmites mauritianus as models

“…Tetramesa romana damages A. donax by producing galls in the stems and lateral shoots. Damage (number of exit holes) was highly variable across sites, however, was overall relatively low (LTS – 19% and NWS – 26% had damage) compared with surveys in North America (Dudley et al ., 2008). Tetramesa romana populations were highly dependent on the season, being most abundant in the summer months of November and December.…”

“…Such pre-emptive surveys have proven their worth in the biological control programme on the invasive alien species (IAS) Arundo donax (L.) in North America. Herbivore surveys on A. donax were able to identify that the reed was not enemy free in the adventive range and a specialist herbivore, Tetramesa romana Walker (Hymenoptera: Eurytomidae) had established from an earlier unknown introduction (Dudley et al ., 2006). From this, augmentative biological control could be initiated which involved increasing T. romana populations to heighten their impacts on the reed (Dudley et al ., 2008; Moran et al ., 2017).…”

“…Herbivore surveys on A. donax were able to identify that the reed was not enemy free in the adventive range and a specialist herbivore, Tetramesa romana Walker (Hymenoptera: Eurytomidae) had established from an earlier unknown introduction (Dudley et al ., 2006). From this, augmentative biological control could be initiated which involved increasing T. romana populations to heighten their impacts on the reed (Dudley et al ., 2008; Moran et al ., 2017). There have been a number of similar examples of herbivore surveys uncovering the accidental introduction of native specialists on IAS and thus revealing that, unlike what the ERH predicts, these plants are no longer strictly enemy free in the adventive range (McClay, 1988; Hoffmann & Moran, 1991).…”

Giant reed (Arundo donax L.): A weed plant or a promising energy crop?

“…Although an Arundo wasp of Spanish genotype has been selected as the mostly suitable for a mass field releases , this insect seems to be unable to reduce significantly the total giant reed biomass (Dudley et al, 2008). The same tendency has been observed in R. donacis that negatively affects specifically the lateral shoots stems that are only minimally involved in total giant reed biomass (Cortés et al, 2011).…”

“…The herbivores Melanaphis donacis (Passerini), Tetramesa romana (Walker) (Hymenoptera: Eurytomidae), Rhizaspidiotus donacis (Leonardi) (Hemiptera: Diaspididae), Cryptonevra sp. (Diptera: Chloropidae) and Lasioptera donacis (Coutin and Faivre-Amiot) (Diptera: Cecidomyiidae), have been evaluated as candidates in A. donax biological control (Seawright et al, 2009;Moran and Goolsby, 2009;Dudley et al, 2008). Among these, T. romana (Arundo wasp) and R. donacis showed the most promising features as biological control agents and show host specificity for giant reed .…”