Search

Many animals have evolved associations with symbiotic microbes that benefit the host through increased growth, lifespan, and survival. Some interactions are obligate (essential for survival) while others are facultative (usually beneficial but not essential). Not all individuals host all facultative symbionts in a population, and thus there is probably a trade-off between the cost of hosting these symbionts and the benefits they confer to the host. Plant-sucking insects have been one of the most important models to test these costs and benefits experimentally. This research is now moving beyond the description of symbiont effects towards understanding the mechanisms of action, and their role in the wider ecological community. We present a quantitative and systematic analysis of the published evidence exploring this question. We found that whitefly and true bugs experience benefits through increased growth and fecundity, whereas aphids experience costs to their fecundity but benefits through increased resistance to natural enemies. We also report the lack of data in some plant-sucking groups, and explore variation in effect strengths and directions across aphid host, symbiont and plant species thus highlighting the importance of considering the context dependency of these interactions.

Dendrothripoides moundi sp.n. Female macroptera. Slide-mounted macerated females bicolored (Fig. 1); head, pronotum, metanotum, first abdominal segment and legs pale yellow; abdominal segments II–X golden brown; antennal segments I–V yellow, VI mainly yellow but with apex brown (Fig. 5), VII–VIII brown; fore wing with three white and two black areas as following: white at base also with white band distal to veinal fork and at apex, small dark marking near base and median area (Fig. 6). Antennae 8-segmented, segments III and IV with forked sense cones, IV and V weakly pedicelate, III–VI rounded at each side (Fig. 5). Ocellar setae III arising on lateral side of ocellar triangle, shorter than distance between hind ocelli (Fig. 2). Pronotum (Fig. 3) without distinct sculpture lines, with about 40 discal setae well-developed, posteroangular setae spatulate (Fig. 3) with four pairs of posteromarginal setae. Mouth-cone long and stout, extending just beyond posterior margin of prosternum (Fig. 3). Mesonotum with polygonal sculpture (Fig. 4), without campaniform sensilla. Metanotum medially with polygonal sculpture, median pair of setae behind anterior margin; campaniform sensilla present (Fig. 4). Fore wing first vein with 1 + 4 and 2 setae on distal third; clavus with 4 marginal setae and no discal setae. Abdomen relatively short and broad; segment X tubular, heavy, longitudinally grooved. Tergite I dorsally with 3–4 anastomosing transverse lines of sculpture; tergites II–VIII with conspicuous stout microtrichia about 8–10 microns long on triangular warts in about five rows, covering more than two-thirds of the dorsal aspect (Fig. 9); II–VII with S1 setae shorter than S2 setae, 5 and 16 microns long respectively, posteromarginal setae (S3) stouter and curved, about 30 microns long, and on II–V setae S4 only about 20 microns long; tergite VIII with S1 setae almost as long as S2 setae; tergites IX and X with setae S1, S2 and S3 spine-like, long and dark (Fig. 11). Sternites II–VII each with about 3 pairs of setae on posterior margin. Measurements (holotype female, in microns). Body length 1233. Head, length 96; width across eyes 130; ocellar setae I 7, III 8; four pairs of postocular setae 12–13. Pronotum, length 114; width 195; posteroangular setae 34. Posteromedial setae 18; four pairs of posteromarginal setae 8–12. Fore wing length 471. Antennal segments I–VII length 16, 24, 38, 44, 30, 40, 10, 18. Tergite VIII S1 length 48, S2 55; tergite IX S1 length 111, S2 length 125, S3 length 101. Tergite X S1 length 92, S2 length 87, S3 length 101. Male macroptera. Similar in structure to female but smaller and slender. Abdominal segments IX and X strongly sclerotized; tergite IX with median pair of short conical setae close to each other, and 3 pairs of small tubercles arranged laterally below median pair of setae; sternites III–VII each with a small transverse pore plate on middle of anterior margin (Fig. 10). Measurements (paratype male in microns). Body length 813. Fore wing 450. Pore plate dimensions on sternites III, IV and V: 23/6; 20/5; 23/4. Type material. Holotype female, Kaominina, Moramanga, MADAGASCAR (lat: -18.94; lon: 48.41; elevation: 909.0 m.a.s.l.), on flowers of Lantana camara, 15.iv.2018 (Enric Frago) in the collection of insects of the Centre de Biologie pour la Gestion des Populations (CBGP) Montpellier, France. Paratypes: 7 females and 1 male with the same data as holotype in CBGP Montpellier, 1 female in Muséum national d’ histoire Naturelle, Paris. Comments. This species is very similar to D. nakaharai but it differs from it in the colour of the fore wing, the sculpture of the metanotum, the position of the metanotal campaniform sensilla, and the size and shape of the male sternal pore plates.

Key to species of Dendrothripoides 1. Body bicolored, head and thorax yellow in contrast to golden brown abdomen..................................... 2 -. Body not bicolored, largely yellowish..................................................................... 3 2. Fore wing uniformly dark brown to apex, but base with anterior margin narrowly pale extending to short pale cross area at veinal fork; metanotal median area with irregular polygons, one campaniform sensillum placed slightly in advance of the other; male sternal pore plates circular, less than 15 microns in diameter (Philippines)....................... nakaharai Reyes -. Fore wing brown with apex and base pale, but with wide white cross-band distal to veinal fork (Fig. 6); metanotal median area with regular polygons, campaniform sensilla placed side-by-side; sternal pore plates of male transverse, about 20 microns wide and 5 microns long (Madagascar)............................................................... moundi sp.n. 3. Abdominal tergites with fine microtrichia arising from equiangular reticulations; tergite VIII with setae S1 and S2 almost equal in length (Philippines)................................................................ microchaetus Okajima -. Abdominal tergites with spine-like microtrichia arising from V-shaped lines of sculpture; tergite VIII with S1 setae slightly shorter than S2 setae................................................................................... 4 4. Pronotal discal setae very small and slightly lanceolate; mouth-cone conical, extending between fore coxae; abdominal tergites VI���VII with S1 setae much larger than S2 setae (Pantropical)...................................... innoxius (Karny) -. Pronotal discal setae large and distinctly lanceolate; mouth-cone long and slender, extending beyond fore coxae; abdominal tergites VI���VII with S1 setae much smaller than S2 setae...................................................... 5 5. Fore wing mainly dark brown, with small white area near base distally; males with large oval pore plates (Southern Africa).......................................................................................... venustus Faure -. Fore wing with two dark areas separated by two white areas; males with pore plates small and circular (Thailand)...................................................................................................... poni Kudo, Published as part of Goldarazena, Arturo, Matsumoto, Masami, Ranarilalatiana, Tolotra, Dianzinga, Niry T., Frago, Enric & Michel, Bruno, 2020, Dendrothripoides moundi (Thysanoptera, Thripidae), a new species from Madagascar, pp. 396-400 in Zootaxa 4877 (2) on page 397, DOI: 10.11646/zootaxa.4877.2.12, http://zenodo.org/record/4424080

Thrips reunionensis sp.n. Female macroptera. Colour of macerated slide mounted females brown (Fig. 1), legs brown with tibia and tarsi yellow; antennal segments I���II brown, III mainly yellow (Fig. 7), IV���V yellow at base; fore wing shaded with basal area close to the clavus slightly clearer. Antennae 7-segmented. Ocellar setae III arising on the lateral side of the triangle, shorter than the distance between hind ocelli (Fig. 6). Pronotum with many transverse sculpture lines not closely spaced, about 40 discal setae, posteroangular setae about 0.6 as long as pronotum with 4 pairs of posteromarginal setae (Fig. 2). Mesonotal anteromedian campaniform sensilla present. Metanotum medially with longitudinal row of large slightly elongate reticles that lack internal markings, median setae not on anterior margin; campaniform sensilla present (Fig. 5). Fore wing first vein almost complete with 2 setae on distal third (Fig. 3); clavus with 5 marginal setae and 1 discal setae (Fig. 8). Abdominal tergites with sculpture lines extending to seta S2 but not between S1 and the campaniform sensilla (Fig. 13); tergite II with 3 lateral marginal setae (Fig. 11); ctenidia present on V���VIII. Pleurotergites with no discal setae and without microtrichia. Tergite VIII with comb of microtrichia complete, long and slender (Fig. 14). Sternites III���VII with 10���15 discal setae in one irregular row (Figs 9���10); II without discal setae and with 2 pairs of marginal setae. Measurements (holotype female in microns). Body length 1710. Head, length 121; width across eyes 146; ocellar setae II 9, III 23. Pronotum, length 128; width 230; posteroangular setae 85, 84. Fore wing length 997. Antennal segments I���VII length 26, 40, 65, 66, 46, 57, 15. Male. Similar to female but smaller and yellow (Fig. 4). Tergite VIII posteromarginal comb absent, microtrichia absent also laterally. Tergite IX setal pair S2 arising slightly behind pair S1, but arranged almost in straight line. Sternites III���VII each with transverse oval pore plate and one or two pairs of discal setae (Fig. 12). Specimens studied. Holotype female, La Reunion Island, on flowers of Dombeya sp. (Malvaceae), 14.vi.2018 (Enric Frago and Niry Dianzinga) in the collection of insects of the Centre de Biologie pour la Gestion des Populations (CBGP) Montpellier, France. Paratypes: 6 females and 12 males with the same data as holotype in CBGP Montpellier, 1 female and 1 male in Mus��um national d��� Histoire naturelle, Paris. Comments. Using the key by Mound (2010) this species tracks to couplets 24 and 25 but it differs from Thrips kurahashii in the position of ocellar setae III and the presence of metanotal campaniform sensilla. The colour also is different, yellow in T. kurahashii and brown in T. reunionensis. Mound (2010) noted variation in Thrips acaciae but that species has four lateral marginal setae on tergite II, more than 24 discal setae in sternites III���VII and a weak comb of microtrichia on tergite VIII posterior margin. Because in Thrips the number of antennal segments within species may vary from seven to eight this species could be confused also with specimens of Thrips simplex with seven antennal segments. However, the male of simplex is black with longer and wider pore plates, and in both sexes the metanotal campaniform sensilla are absent and the metanotal reticles have internal markings. Moreover, the fore wings of T. simplex have a long white proximal area that is light brown in T. reunionensis., Published as part of Goldarazena, Arturo, Dianzinga, Niry T., Frago, Enric, Michel, Bruno & Reynaud, Philippe, 2020, A new species of the genus Thrips (Thysanoptera, Thripidae) from the Malagasy Region, pp. 443-446 in Zootaxa 4750 (3) on pages 443-446, DOI: 10.11646/zootaxa.4750.3.13, http://zenodo.org/record/3707452, {"references":["Mound, L. A. (2010) Species of the genus Thrips (Thysanoptera, Thripidae) from the Afro-tropical region. Zootaxa, 2423 (1), 1 - 24. https: // doi. org / 10.11646 / zootaxa. 2423.1.1"]}

Goldarazena, Arturo, Dianzinga, Niry T., Frago, Enric, Michel, Bruno, Reynaud, Philippe (2020): A new species of the genus Thrips (Thysanoptera, Thripidae) from the Malagasy Region. Zootaxa 4750 (3): 443-446, DOI: https://doi.org/10.11646/zootaxa.4750.3.13

Elevational gradients are a powerful tool to explore how species communities respond to changes in environmental conditions along short geographic distances. It is usually observed that species di-versity decrease monotonically with elevation, or follow a mid-elevation peak. These effects, however, may vary among taxa and geographic regions. Changes driven by elevation may also depend on land-scape characteristics like habitat heterogeneity and patchiness, but also on seasonal variations such as those occurring between cold and hot seasons. Here, we used as biological model thrips (Insecta: Thysanoptera), which is a diverse group of slender insects, to investigate the drivers of insect diversity and of community composition along elevational gradients in Reunion Island. We sampled thrips on 106 plant species belonging to 44 families along seven replicated elevated gradients from 0 to 1,600 m in both summer and winter conditions. We identified 4,278 specimens representing 41 species and we estimated their diversity both at the local (alpha) and at the compositional (beta) diversity level. These metrics were related with elevation, and with landscape characteristics around each site, which included habitat diversity and patchiness (or fragmentation). We found that different thrips communities are directly related to host plants: invasive plants hosted a large diversity of thrips, whereas some endemic ones hosted unique communities. Elevation, patchiness and season were variables with an evident effect on both alpha and beta diversity. Beta diversity revealed that diversity of thrips was larger at low elevations, and this change was mostly dominated by richness differences (i.e. low elevation sites had more unique species than high elevation ones). Our results show that important diversity patterns can be appreciated through the lens of beta diversity, and may help to understand how regional pools of insects are distributed in relationship with topography, landscape and climatic conditions.

Plants form the base of complex communities on terrestrial ecosystems, and are the basic resource for insect herbivores and their associated natural enemies. Most plants contain flowers, and important interactions occur in these organs. Many insects are flower visitors and are known to be affected by habitat loss, fragmentation, and changes in landscape structure, but few studies have experimentally tested how habitat loss alters the structure of flower-visiting insect communities.In this study we focused on thrips (Insecta: Thysanoptera) as a model system. Previous studies in Reunion have revealed that flowers of the following exotic plants species host highly diverse communities of flower-visiting thrips : Solanum mauritianum, Lantana camara, Ipomea indica. Here, we tested the hypothesis that elimination of S. mauritianum flowers (as an important habitat for adult thrips) will trigger changes in thrips communities in the other two plants.We established replicated communities involving the three plants, and in a paired design, S. mauritanicum flowers were eliminated or not. The effect of this treatment on thrips was assessed during one month, by estimating their abundance, richness (i.e. the number of species) and diversity (shanon and simpson indexes). A community of eleven native and exotic thrips species was found. The treatment did not have any effect on insect abundance or diversity, but it had an effect on richness: elimination of S. mauritianum flowers had a negative effect on the richness of the number of species found on L. camara, but not on I. indica. At the landscape level, we observed that both the proportion of sugarcane and habitat fragmentation correlated with thrips richness. These correlations, however, were only observed when S. mauritianum flowers were eliminated, and not in our controls. Although our study was performed on exotic plant species, we provide evidence that at a fine spatial scale, the loss of a plant species that hosts a large diversity of flower-visiting insects can have consequences that cascade to the community of insects inhabiting other plants. Future studies are needed to unveil whether similar effects occur in communities of non-exotic plants, and to explore the consequences of habitat loss at a larger scale.

The presence of nonprey or nonhosts is known to reduce the strength of consumer– resource interactions by increasing the consumer's effort needed to find its resource. These interference effects can have a stabilizing effect on consumer–resource dynamics, but have also been invoked to explain parasitoid extinctions. To understand how nonhosts affect parasitoids, we manipulated the density and diversity of nonhost aphids using experimental host–parasitoid communities and tested how this affects parasitation efficiency of two aphid parasitoid species. To further study the behavioral response of parasitoids to nonhosts, we tested for changes in parasitoid time allocation in relation to their host‐finding strategies. The proportion of successful attacks (attack rate) in both parasitoid species was reduced by the presence of nonhosts. The parasitoid Aphidius megourae was strongly affected by increasing nonhost diversity with the attack rate dropping from 0.39 without nonhosts to 0.05 with high diversity of nonhosts, while Lysiphlebus fabarum responded less strongly, but in a more pronounced way to an increase in nonhost density. Our experiments further showed that increasing nonhost diversity caused host searching and attacking activity levels to fall in A. megourae, but not in L. fabarum, and that A. megourae changed its behavior after a period of time in the presence of nonhosts by increasing its time spent resting. This study shows that nonhost density and diversity in the environment are crucial determinants for the strength of consumer–resource interactions. Their impact upon a consumer's efficiency strongly depends on its host/prey finding strategy as demonstrated by the different responses for the two parasitoid species. We discuss that these trait‐mediated indirect interactions between host and nonhost species are important for community stability, acting either stabilizing or destabilizing depending on the level of nonhost density or diversity present.

National audience; In the process of finding out alternatives to chemical control in horticultural settings in Reunion island, two predatory bugs have been discovered: Orius naivashae (Poppius, 1920) (Heteroptera, Anthocoridae) and Cyrtopeltis callosus Odhiambo, 1961 (Heteroptera, Miridae). These two species are already known in Eastern Africa; they are now established in the island and their voluntary introduction is unlikely. O. naivashae has already been studied in South Africa as a biological control agent, and is therefore a predator with potential interest for controlling pests, especially in integrated pest management programs. However, the biology of C. callosus is so far little known and future studies are needed to allow its use as a biological control agent.; Dans le cadre de recherche de solutions alternatives à la lutte chimique, deux Punaises prédatrices ont été découvertes dans les systèmes de cultures maraîchers de La Réunion : Orius naivashae (Poppius, 1920) (Heteroptera, Anthocoridae) et Cyrtopeltis callosus Odhiambo, 1961 (Heteroptera, Miridae). Ces deux Punaises connues également de l'est de l'Afrique n'ont, a priori, pas été introduites volontairement et sont établies sur l'île de La Réunion. O. naivashae a déjà été étudiée en Afrique du Sud dans le cadre de programmes de lutte biologique et est un prédateur potentiellement intéressant dans le contexte de programmes de lutte intégrée à La Réunion ; la biologie de C. callosus est complètement inconnue et nécessite d'être étudiée avant d'envisager son utilisation en protection des cultures.

Plants respond to insect attack by releasing blends of volatile chemicals that attract their herbivores’ specific natural enemies, while insect herbivores may carry endosymbiotic microorganisms that directly improve herbivore survival after natural enemy attack. Here we demonstrate that the two phenomena can be linked. Plants fed upon by pea aphids release volatiles that attract parasitic wasps, and the pea aphid can carry facultative endosymbiotic bacteria that prevent the development of the parasitic wasp larva and thus markedly improve aphid survival after wasp attack. We show that these endosymbionts also attenuate the systemic release of volatiles by plants after aphid attack, reducing parasitic wasp recruitment and increasing aphid fitness. Our results reveal a novel mechanism through which symbionts can benefit their hosts and emphasise the importance of considering the microbiome in understanding insect ecological interactions., Bacterial symbionts are increasingly known to influence behaviour and fitness in insects. Here, Frago et al. show that plants fed on by aphids with symbionts have altered volatile chemical profiles, leading to reduced parasitoid attack of aphids.