Lateralized courtship in a parasitic wasp.

Lateralization (i.e. left-right asymmetries in the brain and behaviour) of courtship displays has been examined in a growing number vertebrate species, while evidence for invertebrates is limited. In this study, we investigated lateralization of courtship and mating displays in the parasitic wasp Leptomastidea abnormis. Results showed a population-level lateralization of male courtship displays. Male antennal tapping on the female's head was right-biased. However, right-biased male courtship acts were not characterized by higher male antennal tapping frequencies, nor success in mating although antennal tapping frequency was higher in males with mating success with respect to unsuccessful males. Overall, our results add basic knowledge to the behavioural ecology of insect parasitoids. To the best of our knowledge, this is the first report of behavioural lateralization in parasitic Hymenoptera.

Lateralisation of aggressive displays in a tephritid fly.

Lateralisation (i.e. different functional and/or structural specialisations of the left and right sides of the brain) of aggression has been examined in several vertebrate species, while evidence for invertebrates is scarce. In this study, we investigated lateralisation of aggressive displays (boxing with forelegs and wing strikes) in the Mediterranean fruit fly, Ceratitis capitata. We attempted to answer the following questions: (1) do medflies show lateralisation of aggressive displays at the population-level; (2) are there sex differences in lateralisation of aggressive displays; and (3) does lateralisation of aggression enhance fighting success? Results showed left-biased population-level lateralisation of aggressive displays, with no consistent differences among sexes. In both male-male and female-female conflicts, aggressive behaviours performed with left body parts led to greater fighting success than those performed with right body parts. As we found left-biased preferential use of body parts for both wing strikes and boxing, we predicted that the left foreleg/wing is quicker in exploring/striking than the right one. We characterised wing strike and boxing using high-speed videos, calculating mean velocity of aggressive displays. For both sexes, aggressive displays that led to success were faster than unsuccessful ones. However, left wing/legs were not faster than right ones while performing aggressive acts. Further research is needed on proximate causes allowing enhanced fighting success of lateralised aggressive behaviour. This is the first report supporting the adaptive role of lateralisation of aggressive displays in insects.

First report of behavioural lateralisation in mosquitoes: right-biased kicking behaviour against males in females of the Asian tiger mosquito, Aedes albopictus.

Lateralisation (i.e. functional and/or structural specialisations of left and right sides of the brain) of aggressive traits has been studied in a number of vertebrates, while evidence for invertebrates is scarce. Mosquito females display aggressive responses against undesired males, performing rejection kicks with the hind legs. In this research, we examined lateralisation of kicking behaviour in females of the Asian tiger mosquito, Aedes albopictus. We found a right-biased population-level lateralisation of kicking behaviour. Four repeated testing phases on mosquito females confirmed the preferential use of right legs. However, when left legs were used, the mean number of kicks per rejection event was not different to that performed with right legs. Both left and right kicking behaviour lead to successful displacement of undesired partners. This is the first report about behavioural lateralisation in mosquitoes.

Predation by Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against the dengue vector, Aedes aegypti, in an aquatic environment treated with mosquitocidal nanoparticles.

Aedes aegypti is a primary vector of dengue and chikungunya. The use of synthetic insecticides to control Aedes populations often leads to high operational costs and adverse non-target effects. Botanical extracts have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles, but their impact against predators of mosquito larvae has not been well studied. We propose a single-step method for the biosynthesis of silver nanoparticles (AgNP) using the extract of Artemisia vulgaris leaves as a reducing and stabilizing agent. AgNP were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). SEM and XRD showed that AgNP were polydispersed, crystalline, irregularly shaped, with a mean size of 30-70 nm. EDX confirmed the presence of elemental silver. FTIR highlighted that the functional groups from plant metabolites capped AgNP, stabilizing them over time. We investigated the mosquitocidal properties of A. vulgaris leaf extract and green-synthesized AgNP against larvae and pupae of Ae. aegypti. We also evaluated the predatory efficiency of Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against larvae of Ae. aegypti, under laboratory conditions and in an aquatic environment treated with ultra-low doses of AgNP. AgNP were highly toxic to Ae. aegypti larval instars (I-IV) and pupae, with LC50 ranging from 4.4 (I) to 13.1 ppm (pupae). In the lab, the mean number of prey consumed per tadpole per day was 29.0 (I), 26.0 (II), 21.4 (III), and 16.7 (IV). After treatment with AgNP, the mean number of mosquito prey per tadpole per day increased to 34.2 (I), 32.4 (II), 27.4 (III), and 22.6 (IV). Overall, this study highlights the importance of a synergistic approach based on biocontrol agents and botanical nano-insecticides for mosquito control.

Associative learning for danger avoidance nullifies innate positive chemotaxis to host olfactory stimuli in a parasitic wasp.

Animals rely on associative learning for a wide range of purposes, including danger avoidance. This has been demonstrated for several insects, including cockroaches, mosquitoes, drosophilid flies, paper wasps, stingless bees, bumblebees and honeybees, but less is known for parasitic wasps. We tested the ability of Psyttalia concolor (Hymenoptera: Braconidae) females to associate different dosages of two innately attractive host-induced plant volatiles (HIPVs), ethyl octanoate and decanal, with danger (electric shocks). We conducted an associative treatment involving odours and shocks and two non-associative controls involving shocks but not odours and odours but not shocks. In shock-only and odour-only trained wasps, females preferred on HIPV-treated than on blank discs. In associative-trained wasps, however, P. concolor's innate positive chemotaxis for HIPVs was nullified (lowest HIPV dosage tested) or reversed (highest HIPV dosage tested). This is the first report of associative learning of olfactory cues for danger avoidance in parasitic wasps, showing that the effects of learning can override innate positive chemotaxes.

Cues Triggering Mating and Host-Seeking Behavior in the Aphid Parasitoid Aphidius colemani (Hymenoptera: Braconidae: Aphidiinae): Implications for Biological Control.

Aphidius colemani Viereck (Hymenoptera: Braconidae: Aphidiinae) is a pan-tropical, broadly oligophagous, solitary endoparasitoid of many aphids of economic importance. Here, we review current knowledge about this important biological control agent, with a special focus on the physical and chemical cues triggering mating and host-seeking behavior. First, we focus on female-borne olfactory cues evoking courtship in A. colemani males, as well as on the relationship between male mating performance and quality of the host species. Second, we examine how A. colemani females forage for hosts and assess their suitability, using both aphid-borne kairomones and host-related physical cues. Third, we review A. colemani-based biological control approaches, outlining how knowledge of its reproductive behavioral ecology may enhance biological control of aphid pests. Concepts for future biocontrol programs are outlined, including 1) use of sex attractant dispensers for monitoring, 2) mass-rearing optimization based on knowledge of mate-finding strategies and sexually selected traits, 3) deployment of aphid-borne foraging kairomones as field lures to attract parasitoids into infested agro-ecosystems, 4) use of sensitization or associative learning practices to optimize efficacy of mass-reared wasps.

Release and establishment of the parasitoid Diachasmimorpha kraussii against the tephritid fruit fly Bactrocera latifrons in Hawaii.

Diachasmimorpha kraussii (Fullaway) (Hymenoptera: Braconidae) was first released against Bactrocera latifrons (Hendel) (Diptera: Tephritidae) in Hawaii in March 2003. Over a three month period, eight releases, totaling 7,696 females and 3,968 males, were made in a turkeyberry, Solanum torvum Swartz (Solanales: Solanaceae) patch known to have a well established B. latifrons population. The establishment of D. kraussii was assessed through fruit collections conducted over a three-year period beyond the last release. D. kraussii was recovered 2 weeks, 31 months, and 39 months after the last parasitoid release, with collections not only from the release site, but also from a control site about 5.0 km distance from the release site. Recovery from fruit collections three years after the last parasitoid release confirmed that D. kraussii had become established in Hawaii. Parasitism rates were low, only 1.0-1.4%, compared to rates of 2.8-8.7% for the earlier established egg-larval parasitoid, Fopius arisanus (Sonan).

Induced niche shift as an anti-predator response for an endoparasitoid.

When two developmental stages do not share the same ecological niche, the control of the niche shift through a change in developmental timing, referred to as 'heterokairy', can provide an adaptive advantage for the individual (e.g. if mortality risk is higher in the first niche). For endoparasitic species that develop inside another (host) species, mortality of the host may directly induce mortality risk for the parasite. Thus, endoparasitoid larvae should be selected for response to host predation. In this study, aphids previously parasitized by the endoparasitoid Endaphis fugitiva, Gagné and Muratori (Diptera: Cecidomyiidae), were experimentally exposed to increased mortality risks. Both simulated attack and actual predator attacks against aphid hosts induced early emergence of the parasitoid larvae. Parasitoid emergence from the aphids occurred several minutes before the predator finished feeding on the aphid, allowing enough time for the parasitoid larvae to avoid direct predation. Predator-induced emergence produced significantly smaller parasitoid larvae than controls, but, interestingly, no effect on Endaphis adult size was found. To our knowledge, this is the first evidence of induced emergence in an insect parasitoid, but we suggest that this mechanism might be at work in many other species where plasticity in development time allows the individual to perform an adaptive niche shift.

The Structure and Phenology of Non-Native Scolytine Beetle Communities in Coffee Plantations on Kaua'i.

Populations and communities are known to respond to abiotic conditions, but the forces determining the distribution of particular insect pests are sometimes overlooked in the process of developing control methods. Bark and ambrosia beetles (Curculionidae: Scolytinae) are important pests of crops, forestry, and ecosystems worldwide, yet the factors that influence their success are unknown for many species. The Hawaiian archipelago is host to over three dozen invasive scolytines, many of which occur on Kaua'i and are pests of agriculture. We analyzed scolytine community dynamics at two coffee estates: a hand-harvested site in a tropical wet forest and a mechanically harvested site in a tropical dry savanna. Our regression analyses show overall scolytine abundance was negatively correlated with rainfall, as were four species: the tropical nut borer (Hypothenemus obscurus), H. brunneus, Cryphalus longipilus, and Xyleborinus andrewesi. These relationships contributed to the compositions of the communities being markedly dissimilar despite having the same species richness. Multivariate analysis found no influence from temperature or harvest method on community dynamics. This information can be valuable for the timing of pest control methods, for predicting the success of possible new scolytine arrivals on Kaua'i, and for forecasting how these species may spread with climate change.

Feeding and attraction of non-target flies to spinosad-based fruit fly bait.

A spinosad-based fruit fly bait, GF-120, has recently become a primary tool for area-wide suppression or eradication of pest tephritid fruit flies. The present study assessed the attraction and feeding of five non-target fly species to GF-120 in Hawaii. These non-target flies include three beneficial tephritid species [Eutreta xanthochaeta (Aldrich), Tetreuaresta obscuriventris (Loew), Ensina sonchi (L.)] introduced for weed biological control, an endemic Hawaiian tephritid [Trupanea dubautiae (Bryan)] (all Diptera: Tephritidae) and the cosmopolitan Drosophila melanogaster Meigen (Diptera: Drosophilidae). All five non-target fly species were susceptible to GF-120, as was the target pest Mediterranean fruit fly Ceratitis capitata (Wiedemann). Feeding on, or even brief tasting of, GF-120 killed all fly species within 2 h. When individual flies were provided with a choice of GF-120 or honey solution, there was no difference in the frequency of first food encounter by E. xanthochaeta, D. melanogaster or C. capitata. The other three non-target species approached honey more often than GF-120 in their first food encounter. Feeding times on GF-120 and honey were not significantly different for D. melanogaster and C. capitata, while the other four non-target species fed longer on honey than on GF-120. There was no significant difference in feeding time on honey versus GF-120 between males and females of each species. These results suggest that area-wide treatment using GF-120 for the purpose of eradication of pest fruit flies has potential negative impacts on these and other non-target fly species in Hawaii.

Population-level lateralized aggressive and courtship displays make better fighters not lovers: evidence from a fly.

Lateralization (i.e., left-right asymmetries in the brain and behavior) of aggressive and courtship displays has been examined in many vertebrate species, while evidence for invertebrates is limited. We investigated lateralization of aggressive and courtship displays in a lekking tephritid species, the olive fruit fly, Bactrocera oleae. Results showed a left-biased population-level lateralization of aggressive displays, with no differences between the sexes. In both male-male and female-female contests, aggressive behaviors performed with left body parts led to greater fighting success than those performed with right body parts, while no differences in fighting duration were found. Olive fruit fly males also showed a side bias during courtship and mating behavior, courting females more frequently from the left than the right, front, or back sides. No differences were detected between courtship duration and copulation duration following the different male directional approaches. Male mating success was comparable whether females were approached from the left, right, front, or back side. Lateralized aggressive and courtship displays at the population-level may be connected to the prolonged social interactions occurring among lekking flies. Further research is needed on possible benefits arising from lateralization of courtship traits in insects.

Contest experience enhances aggressive behaviour in a fly: when losers learn to win.

In several animal species, aggressive experience influences the characteristics and outcomes of subsequent conflicts, such that winners are more likely to win again (the winner effect) and losers more likely to lose again (the loser effect). We tested the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae), as a model system to evaluate the role of the winner and loser effects in male-male territorial contests. Further, we conducted experiments to test if winning and losing probabilities are affected only by the outcome of the previous contests, or whether the fighting experience itself is sufficient to induce an effect. Both winners and losers of two consecutive encounters displayed higher intensity of aggression and fought longer in subsequent contests. In both cases, they achieved higher fighting success than naïve males. The enhanced fighting performance of both winners and losers was stimulated by merely experiencing a contest, not necessarily by the relative outcome of previous fights. Overall, this study highlights the fact that previous victories and defeats both enhance aggressive behaviour in olive fruit flies, allowing them to achieve higher fighting success in subsequent contests against inexperienced males.

Eco-friendly control of malaria and arbovirus vectors using the mosquitofish Gambusia affinis and ultra-low dosages of Mimusops elengi-synthesized silver nanoparticles: towards an integrative approach?

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. However, the use of synthetic insecticides to control Culicidae may lead to high operational costs and adverse non-target effects. Plant-borne compounds have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles. Their impact against biological control agents of mosquito larval populations has been poorly studied. We synthesized silver nanoparticles (AgNP) using the aqueous leaf extract of Mimusops elengi as a reducing and stabilizing agent. The formation of AgNP was studied using different biophysical methods, including UV-vis spectrophotometry, TEM, XRD, EDX and FTIR. Low doses of AgNP showed larvicidal and pupicidal toxicity against the malaria vector Anopheles stephensi and the arbovirus vector Aedes albopictus. AgNP LC50 against A. stephensi ranged from 12.53 (I instar larvae) to 23.55 ppm (pupae); LC50 against A. albopictus ranged from 11.72 ppm (I) to 21.46 ppm (pupae). In the field, the application of M. elengi extract and AgNP (10 × LC50) led to 100 % larval reduction after 72 h. In adulticidal experiments, AgNP showed LC50 of 13.7 ppm for A. stephensi and 14.7 ppm for A. albopictus. The predation efficiency of Gambusia affinis against A. stephensi and A. albopictus III instar larvae was 86.2 and 81.7 %, respectively. In AgNP-contaminated environments, predation was 93.7 and 88.6 %, respectively. This research demonstrates that M. elengi-synthesized AgNP may be employed at ultra-low doses to reduce larval populations of malaria and arbovirus vectors, without detrimental effects on predation rates of mosquito natural enemies, such as larvivorous fishes.

Oviposition of the invasive two-spotted leafhopper on an endemic tree: effects of an alien weed, foliar pubescence, and habitat humidity.

The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is an exotic pest from South-East Asia that attacks a wide variety of plant species in Hawaii. Myrica faya Aiton is an aggressive exotic weed that displaces and excludes native plants in Hawaiian forests. It has been argued that because of the high nutritional quality of its foliage, M. faya might facilitate leafhopper invasion of native Hawaiian ecosystems that were originally dominated by the endemic tree Metrosideros polymorpha (Gaudichaud). In the present study, we quantified suitability of M. faya and M. polymorpha as ovipositional hosts for S. rufofascia. Overall, leafhoppers preferred to deposit their eggs into the foliage of M. faya. M. faya presence in the area did not affect leafhopper oviposition on M. polymorpha. Foliar pubescence provided good protection of hirsute morphotypes of M. polymorpha. At the same time, glabrous M. polymorpha morphotypes were quite suitable for leafhopper oviposition. There was no difference in the abundance of leafhopper eggs along a precipitation gradient. Our results confirm that invasion of native Hawaiian forests by the weed M. faya will facilitate their invasion by S. rufofascia. Because of the broad host range characteristic of the two-spotted leafhopper, this build-up may adversely affect a number of endemic plant species growing in native forests.

The Coffee Berry Borer (Hypothenemus hampei) Invades Hawaii: Preliminary Investigations on Trap Response and Alternate Hosts.

In August 2010 the coffee berry borer, Hypothenemus hampei, was first reported to have invaded the Kona coffee growing region of Hawaii, posing a severe economic challenge to the fourth largest agricultural commodity in the State. Despite its long and widespread occurrence throughout the tropics as the most serious pest of coffee, there are still discrepancies in the literature regarding several basic aspects of berry borer biology relevant to its control. In Kona coffee plantations, we investigated the beetles' response to several trap and lure formulations, and examined the occurrence of beetles in seeds of alternate host plants occurring adjacent to coffee farms. While traps were shown to capture significant numbers of beetles per day, and the occurrence of beetles in alternate hosts was quite rare, the unique situation of coffee culture in Hawaii will make this pest extremely challenging to manage in the Islands.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 June 2010 - 31 July 2010.

This article documents the addition of 205 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Bagassa guianensis, Bulweria bulwerii, Camelus bactrianus, Chaenogobius annularis, Creontiades dilutus, Diachasmimorpha tryoni, Dioscorea alata, Euhrychiopsis lecontei, Gmelina arborea, Haliotis discus hannai, Hirtella physophora, Melanaphis sacchari, Munida isos, Thaumastocoris peregrinus and Tuberolachnus salignus. These loci were cross-tested on the following species: Halobaena caerulea, Procellaria aequinoctialis, Oceanodroma monteiroi, Camelus ferus, Creontiades pacificus, Dioscorea rotundata, Dioscorea praehensilis, Dioscorea abyssinica, Dioscorea nummularia, Dioscorea transversa, Dioscorea esculenta, Dioscorea pentaphylla, Dioscorea trifida, Hirtella bicornis, Hirtella glandulosa, Licania alba, Licania canescens, Licania membranaceae, Couepia guianensis and 7 undescribed Thaumastocoris species.

Extrafloral nectary phenotypic plasticity is damage- and resource-dependent in Vicia faba.

Phenotypic plasticity enables many damaged plants to increase nectar secretion rates from extrafloral nectaries (EFNs), or in the case of broad bean, Vicia faba L. to produce additional EFNs, to attract natural enemies of herbivores. While plants benefit greatly from these defensive mutualisms, the costs of producing EFNs are largely unknown. We hypothesized that if EFN production is costly, then damaged plants with high resource levels would be able to produce more EFNs than plants that are resource-limited. Here, we show that this indirect inducible defence does follow this general pattern. Vicia faba enriched with 6 or 12 g of 14:14:14 NPK fertilizer increased EFN numbers after leaf damage by 46 and 60%, respectively, compared with nutrient-poor plants. Thus, EFN production is both damage- and resource-dependent. Analogous to direct defences, production of EFNs may limit the overall loss of leaf tissue when risk of herbivory increases.