Delimitation and description of the immature stages of a pollinating fig wasp, Ceratosolen solmsi marchali Mayr (Hymenoptera: Agaonidae).

The mutualism between fig trees and their wasp pollinators is a model system for many ecological and evolutionary studies. However, the immature stages of pollinating fig wasps have rarely been studied. We monitored developing fig wasps of known ages and performed a series of dissections at 24 h intervals to identify key developmental traits of Ceratosolen solmsi marchali Mayr (Hymenoptera: Agaonidae), a pollinator of Ficus hispida L. (Moraceae). We identified where in the Ficus ovary eggs were deposited and time to hatch. We were also able to identify the timing and key underlying characters of five larval instars, three sub-pupal stages, and a single prepupal stage. We provide detailed morphological descriptions for the key stages and report some behavioral observations of the wasps in the several developmental stages we recorded. Scanning electron microscope images were taken.

Obligate mutualism within a host drives the extreme specialization of a fig wasp genome.

BACKGROUND: Fig pollinating wasps form obligate symbioses with their fig hosts. This mutualism arose approximately 75 million years ago. Unlike many other intimate symbioses, which involve vertical transmission of symbionts to host offspring, female fig wasps fly great distances to transfer horizontally between hosts. In contrast, male wasps are wingless and cannot disperse. Symbionts that keep intimate contact with their hosts often show genome reduction, but it is not clear if the wide dispersal of female fig wasps will counteract this general tendency. We sequenced the genome of the fig wasp Ceratosolen solmsi to address this question. RESULTS: The genome size of the fig wasp C. solmsi is typical of insects, but has undergone dramatic reductions of gene families involved in environmental sensing and detoxification. The streamlined chemosensory ability reflects the overwhelming importance of females finding trees of their only host species, Ficus hispida, during their fleeting adult lives. Despite long-distance dispersal, little need exists for detoxification or environmental protection because fig wasps spend nearly all of their lives inside a largely benign host. Analyses of transcriptomes in females and males at four key life stages reveal that the extreme anatomical sexual dimorphism of fig wasps may result from a strong bias in sex-differential gene expression. CONCLUSIONS: Our comparison of the C. solmsi genome with other insects provides new insights into the evolution of obligate mutualism. The draft genome of the fig wasp, and transcriptomic comparisons between both sexes at four different life stages, provide insights into the molecular basis for the extreme anatomical sexual dimorphism of this species.

Pollinating fig wasp Ceratosolen solmsi adjusts the offspring sex ratio to other foundresses.

Local mate competition theory predicts that offspring sex ratio in pollinating fig wasps is female-biased when there is only one foundress, and increased foundress density results in increased offspring sex ratio. Information of other foundresses and clutch size have been suggested to be the main proximate explanations for sex ratio adjustment under local mate competition. Our focus was to show the mechanism of sex ratio adjustment in a pollinating fig wasp, Ceratosolen solmsi Mayr, an obligate pollinator of the functionally dioecious fig, Ficus hispida Linn., with controlled experiments in the field. First, we obtained offspring from one pollinator and offspring at different oviposition sequences, and found that offspring sex ratio decreased with clutch size, and pollinators produced most of their male offspring at the start of bouts, followed by mostly females. Second, we found that offspring sex ratio increased with foundress density, and pollinators did adjust their offspring sex ratio to other females in the oviposition patches. We suggest that when oviposition sites are not limited, pollinators will mainly adjust their offspring sex ratio to other foundresses independent of clutch size changes, whereas adjusting clutch size may be used to adjust sex ratio when oviposition sites are limited.

Antennal sensilla of female Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae), a nymphal parasitoid of the spiraling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae).

Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae) is a minute, obligate endoparasitoid against the spiraling whitefly Aleurodicus dispersus nymph. The external morphology and distribution of the antennal sensilla of female E. guadeloupae were observed by scanning electron microscopy. Antennae of female E. guadeloupae were geniculate in shape, which consist of scape with a radicula, pedicel, and flagellum. Eight morphological sensilla types were recorded in the females: nonporous sensilla chaetica (CH-NP) and nonporous sensilla trichodea (ST-NP); uniporous sensilla chaetica (CH-UP) and uniporous sensilla trichodea (ST-UP) with a tip pore, basiconic capitate peg sensilla with numerous pores open at the bottom of the grooves; multiporous sensilla placoid (MSP) with the multiporous cuticular structure; uniporous rod-like sensilla (RO-UP) with robust grooved surfaces and the tremendous apical hole; nonporous finger-like sensilla (FI-NP) with abundant pimples at the bulgy, mortar-shaped short stalk. In order to further explore the host location mechanisms and courtship behavior of E. guadeloupae, the possible roles of the antennal sensilla of this species were discussed.

Chaos of Wolbachia sequences inside the compact fig syconia of Ficus benjamina (Ficus: moraceae).

Figs and fig wasps form a peculiar closed community in which the Ficus tree provides a compact syconium (inflorescence) habitat for the lives of a complex assemblage of Chalcidoid insects. These diverse fig wasp species have intimate ecological relationships within the closed world of the fig syconia. Previous surveys of Wolbachia, maternally inherited endosymbiotic bacteria that infect vast numbers of arthropod hosts, showed that fig wasps have some of the highest known incidences of Wolbachia amongst all insects. We ask whether the evolutionary patterns of Wolbachia sequences in this closed syconium community are different from those in the outside world. In the present study, we sampled all 17 fig wasp species living on Ficus benjamina, covering 4 families, 6 subfamilies, and 8 genera of wasps. We made a thorough survey of Wolbachia infection patterns and studied evolutionary patterns in wsp (Wolbachia Surface Protein) sequences. We find evidence for high infection incidences, frequent recombination between Wolbachia strains, and considerable horizontal transfer, suggesting rapid evolution of Wolbachia sequences within the syconium community. Though the fig wasps have relatively limited contact with outside world, Wolbachia may be introduced to the syconium community via horizontal transmission by fig wasps species that have winged males and visit the syconia earlier.

Molecular approaches to identify cryptic species and polymorphic species within a complex community of fig wasps.

Cryptic and polymorphic species can complicate traditional taxonomic research and both of these concerns are common in fig wasp communities. Species identification is very difficult, despite great effort and the ecological importance of fig wasps. Herein, we try to identify all chalcidoid wasp species hosted by one species of fig, using both morphological and molecular methods. We compare the efficiency of four different DNA regions and find that ITS2 is highly effective for species identification, while mitochondrial COI and Cytb regions appear less reliable, possibly due to the interference signals from either nuclear copies of mtDNA, i.e. NUMTs, or the effects of Wolbachia infections. The analyses suggest that combining multiple markers is the best choice for inferring species identifications as any one marker may be unsuitable in a given case.

[Control effect of parasitic Metaphycus parasaissetiae on host Parasaissetia nigra].

A laboratory test was conducted to study the control effect of parasitic Metaphycus parasaissetiae on its host Parasaissetia nigra. The functional reactions of the parasitism conformed to the Holling Type II Equation, but the parameters of the functional reactions varied with temperature. Taking the ratio of instant attack rate to preying time (a/T(h)) as an evaluation index, the preying efficiency at 30 degrees C was the highest, with a/T(h) being 23.4211. There was a stronger interference effect in the functional reactions of the parasitism within M. parasaissetiae populations. With the increase of the population density, the amounts of parasitism decreased gradually. Hassell Equation (E = QP(-m)) could describe the relationships between the searching efficiency of M. parasaissetiae and its population density much precisely within the range of 21 degrees C - 33 degrees C. The interference increased with temperature within the range of 21 degrees C - 27 degrees C, and the interference coefficient reached the highest (0.6626) at 27 degrees C. When the temperature was raised to 30 and 33 degrees C, the interference coefficient decreased to 0.6161 and 0.5916, respectively. In the prophase of egg-laying, the parasitized P. nigra could be entirely controlled by M. parasaissetiae. However, when a few larvae were crawling out, the control effect was declined to 81.4%.