Ophelimus bipolaris sp. n. (Hymenoptera, Eulophidae), a New Invasive Eucalyptus Pest and Its Host Plants in China

Eucalyptus species have become one of the most commonly planted trees worldwide, including China, due to their fast growth and various commercial applications. However, the productivity of Eucalyptus plantations has been threatened by exotic invasive insect pests in recent years. Among these pests, gall inducers of the genus Ophelimus of the Eulophidae family are among the most important invasive species in Eucalyptus plantations. We report here for the first time the presence of a new invasive Eucalyptus gall wasp, Ophelimus bipolaris sp. n., in Guangzhou, China, which also represents the first species of the genus reported from China. The identity of the new species was confirmed by an integrative approach combing biological, morphological and molecular evidence. The new species is described and illustrated. This wasp induces galls only on the leaf blade surface of four Eucalyptus species: E. grandis, E. grandis × E. urophylla, E. tereticornis and E. urophylla. Our preliminary observation showed that O. bipolaris could complete a life cycle on E. urophylla in approximately 2 months under local climatic conditions (23.5–30 °C). Considering the severe damage it may cause to Eucalyptus production, further investigations of its biology and control are urgently needed in China.

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

Gall-inducing insects live within plant tissues and induce tumor-like growth that provides insects with food, shelter, and protection from natural enemies. Interestingly, these insects can be precisely targeted by parasitoids. However, the chemical mechanism of the host location by parasitoids of gall-inducing insects has not been elucidated. Empirical evidence has shown that sensory genes play a key role in the host location of parasitoids. To date, the sensory genes that regulate parasitoids to locate gall-inducing insects have not been uncovered. An obligate ectoparasitoid, Quadrastichus mendeli Kim & La Salle (Hymenoptera: Eulophidae: Tetrastichinae), is one of the most important parasitoids of Leptocybe invasa, which is a global gall-making pest in eucalyptus plantations. Therefore, Q. mendeli - L. invasa provides an ideal system to study the way that parasitoids use sensory genes in gall-making pests. In this study, we present the transcriptome of Q. mendeli using high-throughput sequencing. In total, 31820 transcripts were obtained and assembled into 26925 unigenes in Q. mendeli. Then, the major sensory genes were identified, and phylogenetic analyses were performed with these genes from Q. mendeli and other model insect species. Three chemosensory proteins (CSPs), 10 gustatory receptors (GRs), 21 ionotropic receptors (IRs), 58 odorant binding proteins (OBPs), 30 odorant receptors (ORs) and 2 sensory neuron membrane proteins (SNMPs) were identified in Q. mendeli by bioinformatics analysis. Our report is the first to obtain abundant biological information on the transcriptome of Q. mendeli that provided valuable information regarding the molecular basis of Q. mendeli perception, and it may help to understand the host location of parasitoids of gall-making pests.

Biological control of eucalyptus Gall wasp, Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) in Punjab, India

In this investigation, biological control of eucalyptus Gall wasp, Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) in Punjab, India was investigated. The genus Leptocybe Fisher & La Salle (Hymenoptera: Eulophidae) was founded with its type species, L. invasa from Israel in 2004. Adult wasps of L. invasa induce galls on the shoots and midribs of leaves of Eucalyptus sp. and also damage nursery seedlings and young plantations. In the present study, survey was carried out from the year 2012 to 2014, on gall wasp infestation in different eucalyptus growing areas of Punjab. Observations revealed that eucalyptus growing areas in Punjab were under the threat of attack by gall wasp, L. invasa. During the present study, biological control agents Megastimus viggianii and Quadrastichus mendeli have been successfully applied in the gall infested areas of Punjab, from 2012 to 2017, where infestation of gall wasp was regularly decreased and came below 10 % by July, 2017. Consequently, Eucalyptus gall forming insect L. invasa has been controlled successfully by applying the biological control through releasing the parasitoids (Megastimus viggianii and Quadrastichus mendeli), in Punjab, India.

Ophelimus mediterraneus sp. n. (Hymenoptera, Eulophidae): a new Eucalyptus gall wasp in the Mediterranean region

We report here for the first time the presence ofOphelimus mediterraneussp. n. in Mediterranean Europe. This species appears to be closely related toOphelimus maskelli, a well-known invasive pest ofEucalyptus. Based on molecular (cytochrome oxidase I, 28S), morphological (multivariate ratio analysis) and bio-ecological investigations, our study gives unambiguous relevant criteria that allow the discrimination between these two species. A full description ofO. mediterraneussp. n. is also provided. The geographic distribution ofO. mediterraneussp. n. as well as its impact onEucalyptusspecies needs to be more widely assessed since its presence may have been confused withO. maskelliin their sympatric introduced areas. Further investigations of potential parasitoids in the native area may thus be welcomed to evaluate classical biological control achievability.

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

Little is known of the olfactory mechanisms of host detection in the ovipositors of endoparasitoids and ectoparasitoids. An endoparasitoid Aprostocetus causalis La Salle & Wu (Hymenoptera: Eulophidae) and an ectoparasitoid Quadrastichus mendeli Kim & La Salle (Hymenoptera: Eulophidae: Tetrastichinae) are the two parasitoids of the eucalyptus gall wasp Leptocybe spp. Structures and sense organs of ovipositors of A. causalis and Q. mendeli were studied using scanning and transmission electron microscopy, which provided essential information for exploring the mechanism of host detection by endoparasitoid and ectoparasitoid. The ovipositors of two parasitoids consisted of the first and second valvulae and ended in a pointed tip. There were three types of microtrichia, two types of sensilla chaetica, and one type of sensilla campaniformia on the ovipositors of A. causalis and Q. mendeli. However, Q. mendeli has the fourth type of microtrichia on the ovipositor. The morphology, types, distribution, length, and width of these sensilla and microtrichia were described, and their possible functions are discussed in conjunction with the stinging, oviposition, and the host selection process.

Biological traits of Quadrastichus mendeli (Hymenoptera, Eulophidae), parasitoid of the eucalyptus gall wasp Leptocybe invasa (Hymenoptera, Eulophidae) in Thailand

Quadrastichus mendeli Kim & La Salle, a parasitoid of Leptocybe invasa Fisher & La Salle, is a uniparental species. This study assessed the biological traits of Q. mendeli in the laboratory at a temperature of 27 ± 1 °C. Diets had a highly significant effect on the mean longevity of female Q. mendeli. Feeding honey solution prolonged the mean longevity of the parasitoid to 4.80 days. The estimated 50% survival period was 3 days. The mean potential fecundity in all ages was 8.85 eggs per female. Age had a highly significant effect on the mean egg load. There was a positive relationship between egg load and female size. The mean of realized fecundity throughout the life span was 2.47 progenies per female. The mean developmental time of Q. mendeli from the egg to adult stage was 27.06 days. The shorter developmental time of Q. mendeli in comparison to its host can be considered a reason for the successful control of L. invasa in Thailand.