Parasitoids of the eucalyptus gall wasp Leptocybe spp.: a global review

Abstract

The genus Leptocybe Fisher & La Salle (Hymenoptera: Eulophidae) and its type species L. invasa were first described in 2004. Leptocybe spp. are global pests of eucalyptus plantations, and parasitoids play an important role in their control. In this review, we describe the species, distribution, biology, ecology and parasitism levels of Leptocybe spp. parasitoids and the problems associated with biological control programmes against Leptocybe spp. Additionally, prospects for the use of conservation or augmentative biological control programmes against Leptocybe spp. are discussed. Worldwide, approximately 23 species of parasitoids of Leptocybe spp. in 7 families and 10 genera have been found to date. Comparing the parasitism levels of the parasitoids showed that Quadrastichus mendeli, Selitrichodes neseri and several (approximately 4) native Megastigmus spp. could be exploited to manage Leptocybe spp. Available information on the Leptocybe spp. parasitoids is expected to improve our understanding related to ongoing studies of biological control programmes against Leptocybe spp.

Sensory Geneidentificationin the Transcriptome of the Ectoparasitoid Quadrastichus Mendeliinthe Eucalyptus Gall wasp Leptocybe Invasa

“…In contrast, the general functional mechanism of SNMP2 in parasitoids is still poorly understood. In addition, Q. mendeli is a uniparental parasitoid that is not required in the male search for mating 22 . Thus, the function of QmenSNMPs may include an oviposition pheromone receptor rather than a sex receptor and a membrane protein with unknown functions, which needs to be further explored.…”

Structure and Sense Organs of Ovipositors of an Endoparasitoid Aprostocetus causalis and an Ectoparasitoid Quadrastichus mendeli in Leptocybe spp.

“…In addition, A. causalis is an amphigenetic endoparasitoid and the use of sensilla is expected to involve in various sensitivities caused by the males (Zheng et al, 2016). By contrast, Q. mendeli is a uniparental ectoparasitoid, which is not required to search for the males for mating (Huang et al, 2018 b ). Moreover, endoparasitoids usually use the large barbs on the first valvulae of ovipositors to lay the egg inside of the host (Vincent & King, 1996).…”

Comparison of bacterial diversity and abundance between sexes of Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) from China

“…2, Table 3). Rhizobium produces a variety of enzymes with cellulose-and pectin-hydrolyzing activities that can hydrolyze the glycoside skeleton of the plant cell wall and play a very important role in the symbiosis between Rhizobium and leguminous plants (Robledo et al, 2008;Huang et al, 2018). Rhizobium is an endosymbiont detected in the gut of some phytophagous insects and can help the host synthesize nitrogen-containing substances that are lacking in food (Russell et al, 2009).…”

“…A new study demonstrated that an increasing number of areas will become suitable for L. invasa due to climate warming (Huang et al, 2019). Every delicate twig, vein and petiole of eucalyptus trees may provide a spawning ground for this pest, and galls ultimately lead to stunted growth of the trees, causing great losses in local eucalyptus plantations (Mendel et al, 2004;Zheng et al, 2014a;Huang et al, 2018). DNA barcode data indicated that L. invasa includes two genetically separate lineages (lineages A and B).…”

“…The absence of natural enemies, presence of large amounts of suitable host plants, small size, protection in galls, strong resistance to low temperature and thelytokous parthenogenesis of L. invasa caused its rapid invasion and growth of in China (Zheng et al, 2014a). As a result, it has become one of the most difficult pests to control (Zheng et al, 2014a;Huang et al, 2018;Le et al, 2018). It is important in tems of theory and application to study the endosymbiotic bacterial diversity of L. invasa and then control the wasps by using these endosymbiotic bacteria.…”