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Eucalypt domestication and breeding

In Sardinia (Italy), Eucalyptus plantations cover approximately 23,000 hectares, above all in the southern part of the island. There is a complex of phytophagous insect pests that is threatening the health status of Eucalyptus trees. The most recent invasions include the sap-suckers, Glycaspis brimblecombei, Blastopsylla occidentalis, and the bronze bug, Thaumastocoris peregrinus. Other pest species have also been reported, including the gall wasps, Ophelimus maskelli and Leptocybe invasa, the longhorn beetles, Phoracantha semipunctata and P. recurva, and the weevils, Gonipterus scutellatus and Polydrusus (= Metallites) parallelus. Defoliation caused by the gypsy moth, Lymantria dispar, have also been frequently observed in various Eucalyptus-planted areas of Sardinia.

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Insect pests of eucalyptus plantations in sardinia (italy)

Research Highlights: We present the first attempts to model the distributions of the two cryptic and globally invasive species of Leptocybe invasa sensu lato (Fisher & LaSalle) (Hymenoptera: Eulophidae) in its purported country of origin, namely Australia. Background and Objectives: Leptocybe invasa is an invasive eucalypt-galling wasp that spread quickly all over the world in the early to mid-2000’s, achieving significant pest status through its severe impacts on the growth and productivity of extra-limital eucalypt plantations. Until its discovery in Europe and the Middle East, the genus was undescribed, and its native range remains unclear. Molecular studies indicate the globally invasive population comprises two cryptic species with variable modes of reproduction. Collection records from Australia, the purported origin, represent only one of the invasive lineages, restricted to subtropical and tropical Queensland and northern New South Wales. To date, the original invasive lineage has not been found in Australia, despite searches over the seventeen years that it has been spreading overseas. Materials and Methods: To understand the distributions of the invasive populations, and to infer Leptocybe spp. native ranges within Australia, we used correlative niche modelling in Maximum Entropy (MaxEnt) and multivariate analysis, and created a CLIMEX model based on development rates of an invasive population. Results: We used the environmental conditions in the extra-limital range to infer possible origins, with our findings supporting the possibility that the invasive populations may have originated from different populations in Australia. Conclusions: We highlight the need for better understanding of the distribution, genetic diversity, and reproductive mode of the species within Australia. The variety of climatic niches occupied by invasive lineages of the wasp potentially present new threats to eucalypts in previously uninfested habitats.

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Where Did You Come From? Where Did You Go? Investigating the Origin of Invasive Leptocybe Species Using Distribution Modelling

Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) is an invasive pest in Eucalyptus plantations around the world. The successful colonization of L. invasa is possibly related to its reproductive biology. The objective of this study was to examine the reproductive biology of L. invasa. In Guangxi Province, the sex ratio (proportion of female, 0.99) of L. invasa was female-dominant throughout the year based on natural and artificial infestation. This result was similar to the ratios observed for other geographic populations in China, including those in Fujian (0.99), Guangdong (0.98), Hainan (0.95), Jiangxi (0.96), and Sichuan (0.99). The offspring sex ratio favored females. A large number of females emerged from the galls produced by females, with few males found. Galls on the petioles and midribs of Eucalyptus plants could be caused by newly emerged females with mature eggs. The lengths of the ovariole, spermatheca, common oviduct, and reproductive glands did not differ among L. invasa females, but their lateral oviducts showed differences from 0 to 42 h after emergence, indicating that this insect is proovigenic. These results could explain why L. invasa populations can rapidly increase in invaded areas.

Reproductive Biology of Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae).

The presence of the invader eucalyptus gall wasp Leptocybe invasa Fischer & La Salle (Hymenoptera: Eulophidae) is recorded for the first time in Mexico. This forest pest has been detected in northern Mexico City, at an elevation of ≈2,240m, with an average temperature of 17.9°C. It has also been detected in the areas of Nezahualcoyotl and Texcoco, State of Mexico; Cuautla, Morelos; Guadalajara, Jalisco and Ciudad Victoria, Tamaulipas. In these states, L. invasa attacked Eucalyptus camaldulensis Dehnh. About 2.6% of the E. camaldulensis trees reported in Mexico City had infestations in about 27% of the twigs. In addition, 25% of the leaves had galls, with an average of 23.5±4.8 galls per branches of 20cm in length.

http://www.revista.ib.unam.mx/index.php/bio/article/download/271/1212

First record of eucalyptus gall wasp Leptocybe invasa (Hymenoptera: Eulophidae) in Mexico

This study explores infestation density of Leptocybe invasa on five commercially grown Eucalyptus species in Coastal, Plateaux, and Southern Highlands agroecological zones of Tanzania. Infestation density between agroecological zones, Eucalyptus species, age classes and tree crown parts, relationship between stand altitudes and the magnitude of infestation, damage index, species age, and abundance of L. invasa on different Eucalyptus species were examined. There were significant differences in infestation between zones and Eucalyptus species. Eucalyptus tereticornis was more affected, followed by E. camaldulensis, and E. saligna was the least while E. grandis and E. citriodora were not affected. No significant differences in damage between different crown parts were observed. Trees with age of 1–3 yr were damaged more than those of age 4–6 yr. Pest infestation increased with an increase of L. invasa abundance but decreased with an increase of altitudes. Control efforts needs to focus on controlling the sp...

Infestation Density of Eucalyptus Gall Wasp, Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae) on Five Commercially Grown Eucalyptus Species in Tanzania

R. Petro

Papers

Infestation Density of Eucalyptus Gall Wasp, Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae) on Five Commercially Grown Eucalyptus Species in Tanzania