Giulia Giunti

Lek dynamics and cues evoking mating behavior in tephritid flies infesting soft fruits : implications for behavior-based control tools

Soft fruits are cultivated in many parts of the world and are heavily attacked by a huge range of arthropod pests, including many Tephritidae flies. Soft fruits are consumed by a broad array of consumers, including children, pregnant women and elderly people; thus, high safety levels are required to ensure their adequate protection. On this basis, ecofriendly control tools against Tephritids Infesting Soft Fruits (TISF) are urgently needed. Despite extensive research carried out on Tephritidae behavioral ecology, little is known about lek dynamics and cues evoking mating behavior in TISF. Here we provide a focused look at this issue, reviewing the current knowledge about sexual communication in TISF. First, we examine pre-courtship lek dynamics and the role of male-male aggression in TISF. Second, we review knowledge about mating behavior sequences, with special reference to chemical (mainly sex pheromones) and physical cues (both vibrational and visual) guiding mate choice dynamics. Third, current and potential Integrated Pest Management applications aimed at area-wide control of TISF are outlined, with special reference to improvement of monitoring, the sterile insect technique, and “lure and kill” tools, including the male annihilation technique based on the sprayable specialized pheromone and lure application technology.

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.

Changes in olive oil volatile organic compounds induced by water status and light environment in canopies of Olea europaea L. trees

BACKGROUND Light and water are major factors in fruit development and quality. In this study, the effect of water and light in Olea europaea trees on volatile organic compounds (VOCs) in olive oil was studied over 2 years. Mature fruits were harvested from three zones of the canopy with different light exposure (64%, 42% and 30% of incident light) of trees subjected to full, deficit or complementary irrigation. VOCs were determined by SPME GC-MS and analysed by principal component analysis followed by discriminant analysis to partition treatment effects. RESULTS Fruit fresh weight and mesocarp oil content decreased in zones where intercepted light was less. Low light levels significantly slowed down fruit maturation, whereas conditions of water deficit accelerated the maturation process. The presence of cyclosativene and α-muurulene was associated with water deficit, nonanal, valencene with full irrigation; α-muurulene, (E)-2-hexanal were related to low light conditions, while trans-β-ocimene, α-copaene, (Z)-2-penten-1-ol, hexanal and nonanal to well exposed zones. The year strongly affected the VOC profile of olive oil. CONCLUSION This is the first report on qualitative changes in VOCs induced by light environment and/or water status. This information is valuable to better understand the role of environmental factors on the sensory quality of virgin olive oil.

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

ABSTRACT 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 femaleborne 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.

Event-Based Prospective Memory in Newly Diagnosed, Drug-Naive Parkinson's Disease Patients

The present study investigated memory for intention in individuals with Parkinsons disease (PD) who were newly diagnosed and not yet treated to avoid the effect of therapy as a potential confounding variable. A comprehensive neuropsychological battery and an event-based prospective memory task were administered to 41 subjects with de novo PD and 40 control subjects. Separate scores were computed for correct execution of intended action (prospective component) and recall of intention (retrospective component). PD patients performed marginally worse (p = .053) than controls on the prospective component of the task. On the other hand, the performance of the two groups was comparable for the retrospective component. Neuropsychological findings revealed lower performance of the PD group in episodic memory and in some measures of executive functions. These results suggested a subtle prospective memory dysfunction present at the initial stage of PD, which may be related to disruption of fronto-striatal circuitry.

The impact of adult diet on parasitoid reproductive performance

Diet is one of the most common influences on parasitoid reproductive traits. The life span, mating ability, fecundity, fertility and sex ratio of parasitoids can be affected by the quality of the adult diet. In the field, parasitoids can rely on different hosts and non-host nutrient sources, such as floral and extrafloral nectar, hemipteran honeydew and pollen, and various artificial diets have been used in mass rearing. In addition, some parasitoid species obtain nutrients by feeding on their host while adult (host feeding). In this review, we summarize current knowledge on the impact of the adult diet on the reproductive behavior of hymenopteran and dipteran parasitoids, with a particular focus on longevity, offspring production and host searching traits. First, we focus on food preferences and learning abilities of parasitoids to discriminate high-quality diets. Second, we analyze the impact of the adult diet on longevity, examining different natural and artificial food sources as well as the effect of their concentration and frequency. Third, we highlight the impact of the adult diet on host foraging. Fourth, we review the impact of adult diet on parasitoid offspring with special reference to (1) egg load, maturation and resorption, (2) parasitism and (3) progeny production and sex ratio. Finally, a number of implications for biological control and integrated pest management are discussed.

Early adult learning affects host preferences in the tephritid parasitoid Psyttalia concolor (Hymenoptera: Braconidae)

Parasitic wasps rely on a hierarchy of stimuli to locate their hosts. Olfactory cues from the natal host complex affect parasitoid preferences and can be learned by parasitoids during larval stages and the early adult stage. While the existence of pre-imaginal conditioning has been documented in several braconid aphid parasitoids, no evidence has yet been provided for parasitic wasps attacking Tephritidae. Psyttalia concolor (Hymenoptera: Braconidae) is a koinobiont larval–pupal endoparasitoid of tephritid flies. In this study, we evaluated the influence of larval and early adult experience on subsequent host seeking in P. concolor females. Parasitoids were reared using Ceratitis capitata or Bactrocera oleae larvae as hosts, and emerging wasp adults were tested for host preferences in two-choice bioassays. P. concolor females preferred to oviposit in, and had higher oviposition success rates on the natal host. When P. concolor females were excised from their host puparia, preventing them from chewing emergence holes, they lost their natal host preference, solidifying the evidence of early adult learning for host selection. This study adds to the growing body of basic knowledge on braconid host-location behavior. From an applied point of view, training procedures for early adult learning has potential for use in mass rearing of parasitoids employed in biological control programs against tephritid flies.

A novel GIS-based approach to assess beekeeping suitability of Mediterranean lands

Honeybees are critically important for the environment and to the economy. However, there are in substantial decline worldwide, leading to serious threat to the stability and yield of food crops. Beekeeping is of pivotal importance, combining the wide economical aspect of honey production and the important ecological services provided by honeybees. In this scenario, the prompt identification of beekeeping areas is strategic, since it maximised productivity and lowered the risks of colony losses. Fuzzy logic is an ideal approach for problem-solving tasks, as it is specifically designed to manage problems with a high degree of uncertainty. This research tested a novel GIS-based approach to assess beekeeping suitability of lands located in Calabria (Southern Italy), without relying to Analytic Hierarchy Process – Multiple Criteria Decision Making (AHP-MCDM), thus avoiding the constraints due to the technique and decision makers’ influences. Furthermore, the data used here were completely retrieved from open access sources, highlighting that our approach is characterized by low costs and can be easily reproduced for a wide arrays of geographical contexts. Notably, the results obtained by our experiments were validated by the actual beekeeping reality. Besides beekeeping, the use of this system could not only be applied in beekeeping land suitability evaluations, but may be successfully extended to other types of land suitability evaluations.

Singing on the wings! Male wing fanning performances affect female willingness to copulate in the aphid parasitoid Lysiphlebus testaceipes (Hymenoptera: Braconidae: Aphidiinae)

Lysiphlebus testaceipes (Hymenoptera: Braconidae: Aphidiinae) is a generalist endoparasitoid attacking more than 100 aphid species. In L. testaceipes, wing fanning is a main male courtship display evoked by a female‐borne sex pheromone. However, no information is available on the characteristics and behavioral role of male fanning during courtship in this parasitoid. Here, the courtship behavior of a wild strain of L. testaceipes was quantified and the male wing fanning performances were analyzed through high‐speed video recordings and examined in relation to mating success. Courtship sequence of wild L. testaceipes did not substantially differ from that previously reported for other populations mass reared on aphids. We observed that the male courtship duration did not affect mating success. However, video analysis revealed that the males producing high‐frequency fanning signals achieved higher mating success over those that display low‐frequency fanning. Wing fanning before successful and unsuccessful courtship differed in amplitude of wing movements and alignment toward the mate, highlighting that frontal courtship positively influence the female mating decisions. This study increases knowledge on sexual behavior in a key parasitoid of aphids, highlighting the importance of wing fanning among the range of sensory modalities used in the sexual communication of L. testaceipes. From a practical point of view, this information is useful in L. testaceipes‐based biocontrol strategies, since it can help to establish parameters for quality checking of mass‐reared wasps over time.

VOC emissions influence intra- and interspecific interactions among stored-product Coleoptera in paddy rice

Olfaction is a pivotal sense for insects and granivorous pests may exploit grain volatiles for food selection. Tribolium confusum, is a secondary pest of stored cereals that benefits from primary pests’ infestation, as other secondary feeders, triggering competition. This study aimed to evaluate the preferences of T. confusum females toward different-infested paddy rice, highlighting the impact of intra- and interspecific competition. Tribolium confusum showed positive chemotaxis toward rice infested by larvae of a primary pest (Sitophilus zeamais), but not for grain attacked by adults alone. Furthermore, kernels concurrently infested by a primary (S. zeamais) and a secondary pest (T. confusum or Cryptolestes ferrugineus) were evaluated in Y-tube bioassays, highlighting that both food-sources were innately attractive for T. confusum females. Moreover, females positively oriented toward rice infested by conspecifics, while they avoided grain infested by C. ferrugineus, averting an extremely competitive habitat. Behavioural responses of T. confusum females and volatile emissions of different-infested rice highlighted the occurrence of plant-mediated interactions among insects from the same trophic guild. Seventy volatiles were identified and significant differences among the tested food-sources were recorded, emphasizing the presence of 6 putative attractants and 6 repellents, which may be useful biocontrol tools.