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Resilience and functionality of European Norway spruce forests are increasingly threatened by mass outbreaks of the bark beetle Ips typographus promoted by heat, wind throw and drought. Here, we review current knowledge on Norway spruce and I. typographus interactions from the perspective of drought-stressed trees, host selection, colonisation behaviour of beetles, with multi-level effects of symbiotic ophiostomatoid fungi. By including chemo-ecological, molecular and behavioural perspectives, we provide a comprehensive picture on this complex, multitrophic system in the light of climate change. Trees invest carbon into specialised metabolism to produce defence compounds against biotic invaders; processes that are strongly affected by physiological stress such as drought. Spruce bark contains numerous terpenoid and phenolic substances, which are important for bark beetle aggregation and attack success. Abiotic stressors such as increased temperatures and drought affect composition, amounts and emission rates of volatile compounds. Thus, drought events may influence olfactory responses of I. typographus, and further the pheromone communication enabling mass attack. In addition, I. typographus is associated with numerous ophiostomatoid fungal symbionts with multiple effects on beetle life history. Symbiotic fungi degrade spruce toxins, help to exhaust tree defences, produce beetle semiochemicals, and possibly provide nutrition. As the various fungal associates have different temperature optima, they can influence the performance of I. typographus differently under changing environmental conditions. Finally, we discuss why effects of drought on tree-killing by bark beetles are still poorly understood and provide an outlook on future research on this eruptive species using both, field and laboratory experiments.

The present study was conducted to determine the role of guava fruit volatiles in attraction, oviposition and associated fitness parameters of the peach fruit fly, Bactrocera zonata Saunders, which is a key pest of guava and many other fruits. B. zonata female flies’ attraction was observed in a Y-tube olfactometer using fruits of three locally grown guava varieties; Gola, Larkana Small Surahi (LSS) and Larkana Large Surahi (LLS). Female flies showed significantly higher levels of attraction to both un-infested and infested guava fruit odors compared to control (blank). In pairwise comparisons between different fruit varieties, females B. zonata showed significantly greater levels of attraction towards un-infested Gola compared to un-infested LSS, while in the case of the same variety, significantly higher number of flies were attracted to un-infested compared to infested fruit in all three tested varieties. In two-choice oviposition bioassays, B. zonata females made significantly more visits, greater numbers of ovipositions, spent a significantly longer time, and larger numbers of pupae and adults developed on Gola fruits compared to LSS fruits. However, in no-choice bioassays, females made more visits and spent a significantly greater amount of time on LSS compared to Gola and LLS. GC–MS analysis of guava headspace revealed presence of aliphatic and aromatic esters as a dominant group of compounds in both un-infested and fruit-fly-infested guava fruits, with a higher quantity mostly occurring in fruit-fly-infested fruits. Role of guava volatiles is discussed in an ecological context of attraction and oviposition behaviors of adult females and fitness of their offspring.

Eurasian spruce bark beetles (Ips typographus) use both attractant and anti-attractant semiochemicals to find suitable mature host trees. Trans-4-thujanol is abundant in young, unsuitable spruce trees. Electrophysiological studies have demonstrated its high activity levels, but field data are lacking.Enantioselective GC-MS analysis showed that only (1R,4S)-(+)-trans-4-thujanol was present in Norway spruce bark volatiles. In a factorial design field-trapping experiment, trans-4-thujanol alone was not attractive to Ips typographus. Traps baited with I. typographus' aggregation pheromone and trans-4-thujanol or the known anti-attractant 1,8-cineole caught fewer beetles than those baited with the aggregation pheromone alone. Catches for trans-4-thujanol and 1,8-cineole were dose-dependent. Intermediate doses of trans-4-thujanol and 1,8-cineole had a similar effect. Surprisingly, in contrast to 1,8-cineole and other known Ips anti-attractants, which all inhibit males more strongly than females, the addition of trans-4-thujanol to the aggregation pheromone reduced the attraction of females more.The Norway spruce volatile (+)-trans-4-thujanol is a novel I. typographus anti-attractant with potency comparable to the known anti-attractants 1,8-cineole and verbenone, and is more effective for females than for males. Incorporating (+)-trans-4-thujanol into anti-attractant lures could improve protection of trees from mass attack by I. typographus.

Plant traits are an expression of strategic tradeoffs in plant performance that determine variation in allocation of finite resources to alternate physiological functions. Climate factors interact with plant traits to mediate tree survival. This study investigated survival dynamics in Norway spruce (Picea abies) in relation to tree-level morphological traits during a prolonged multi-year outbreak of the bark beetle, Ips typographus, in Central Europe. We acquired datasets describing the trait attributes of individual spruce using remote sensing and field surveys. We used nonlinear regression in a hypothesis-driven framework to quantify survival probability as a function of tree size, crown morphology, intraspecific competition and a growing season water balance. Extant spruce trees that persisted through the outbreak were spatially clustered, suggesting that survival was a nonrandom process. Larger diameter trees were more susceptible to bark beetles, reflecting either life history tradeoffs or a dynamic interaction between defense capacity and insect aggregation behavior. Competition had a strong negative effect on survival, presumably through resource limitation. Trees with more extensive crowns were buffered against bark beetles, ostensibly by a more robust photosynthetic capability and greater carbon reserves. The outbreak spanned a warming trend and conditions of anomalous aridity. Sustained water limitation during this period amplified the consequences of other factors, rendering even smaller trees vulnerable to colonization by insects. Our results are in agreement with prior research indicating that climate change has the potential to intensify bark beetle activity. However, forest outcomes will depend on complex cross-scale interactions between global climate trends and tree-level trait factors, as well as feedback effects associated with landscape patterns of stand structural diversity.

Arvicolinae rodents are known pests causing damage to both agricultural and forest crops. Today, rodenticides for rodent control are widely discouraged owing to their negative effects on the environment. Rodents are the main prey for several predators, and their complex olfactory system allows them to identify risks of predation. Therefore, the potential use of predators' scents as repellents has gained interest as an ecologically based rodent control method. In a two-choice experiment, we investigated the potential repellent effects of five synthetic predator compounds: 2-phenylethylamine (2-PEA), 2-propylthietane (2-PT), indole, heptanal and 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), at 1% and 5% doses, using the bank vole (Myodes glareolus) as a rodent model.The compound 2-PEA reduced both the food contacts and the time spent by voles in the treatment arm compared to the control arm. Likewise, 2-PT-treated arms reduced the food contacts, and the voles spent less time there, although this latter difference was not significant. Indole also showed a tendency to reduce the time spent at the treatment arm; however, this result was not significant. Unexpectedly, TMT had the reverse effect in showing attractive properties, possibly due to odor cues from differently sized predators and intraguild predation in nature. We found no dose-related effects for any compounds tested.Our results suggest that the 2-PEA and 2-PT are both effective odor stimuli for triggering reduced food contacts and area avoidance, and they may be good repellent candidates. We suggest further testing of 2-PEA and 2-PT in field experiments to further determine their dose-efficiency as repellents against rodents in more natural environments. © 2022 The Authors. Pest Management Science published by John WileySons Ltd on behalf of Society of Chemical Industry.

Conifer-feeding bark beetles are important herbivores and decomposers in forest ecosystems. These species complete their life cycle in nutritionally poor substrates and some can kill enormous numbers of trees during population outbreaks. The Eurasian spruce bark beetle (Ips typographus) can destroy >100 million m(3) of spruce in a single year. We report a 236.8 Mb I. typographus genome assembly using PacBio long-read sequencing. The final phased assembly has a contig N-50 of 6.65 Mb in 272 contigs and is predicted to contain 23,923 protein-coding genes. We reveal expanded gene families associated with plant cell wall degradation, including pectinases, aspartyl proteases, and glycosyl hydrolases. This genome sequence from the genus Ips provides timely resources to address questions about the evolutionary biology of the true weevils (Curculionidae), one of the most species-rich animal families. In forests of today, increasingly stressed by global warming, this draft genome may assist in developing pest control strategies to mitigate outbreaks.Daniel Powell et al. present a high-quality genome assembly of the Eurasian spruce bark beetle, Ips typographus, which is known to cause substantial damage to European forests. Their results provide an important resource for investigation of the underlying physiology of this pest species and limit future threats to European forests.

Plant volatiles are the invisible players in the plant-insect co-evolutionary arms race. They are involved in various plant-mediated tri-trophic interactions within the ecosystem. Volatiles, emitted from different parts of the plant, serves as a cue for the host-seeking herbivores. Interestingly, insects perceive and process such complex environmental cues with their advanced olfactory system. During herbivory, plants also produce defensive volatiles recognized as herbivore-induced plant volatiles (HIPVs) that often serve a dual purpose by attracting the natural enemies and giving an alarming signal to the plants nearby. Insects tend to avoid the host plants emitting such defensive volatiles and non-host plants, releasing non-host volatiles (NHVs). Understanding the dynamics of host selection through plant volatile recognition by pest insects is highly important to develop eco-friendly pest management practices employing strategies such as push-pull strategy. In the present chapter, we have reviewed different aspects of plant volatile production, insect olfactory system organization, the contribution of plant volatiles in host-seeking behavior of insects, and finally their potential use in formulating insect pest management strategies.

Bark beetles often serve as forest damaging agents, causing landscape-level mortality. Understanding the biology and ecology of beetles are important for both, gathering knowledge about important forest insects and forest protection. Knowledge about the bark beetle gut-associated bacteria is one of the crucial yet surprisingly neglected areas of research with European tree-killing bark beetles. Hence, in this study, we survey the gut bacteriome from five Ips and one non-Ips bark beetles from Scolytinae. Results reveal 69 core bacterial genera among five Ips beetles that may perform conserved functions within the bark beetle holobiont. The most abundant bacterial genera from different bark beetle gut include Erwinia, Sodalis, Serratia, Tyzzerella, Raoultella, Rahnella, Wolbachia, Spiroplasma, Vibrio, and Pseudoxanthomonas. Notable differences in gut-associated bacterial community richness and diversity among the beetle species are observed. Furthermore, the impact of sampling location on the overall bark beetle gut bacterial community assemblage is also documented, which warrants further investigations. Nevertheless, our data expanded the current knowledge about core gut bacterial communities in Ips bark beetles and their putative function such as cellulose degradation, nitrogen fixation, detoxification of defensive plant compounds, and inhibition of pathogens, which could serve as a basis for further metatranscriptomics and metaproteomics investigations.

Resilience and functionality of European Norway spruce forests are increasingly threatened by mass outbreaks of the bark beetle Ips typographus promoted by heat, wind throw and drought. Here, we review current knowledge on Norway spruce and I. typographus interactions from the perspective of drought-stressed trees, host selection, colonisation behaviour of beetles, with multi-level effects of symbiotic ophiostomatoid fungi. By including chemo-ecological, molecular and behavioural perspectives, we provide a comprehensive picture on this complex, multitrophic system in the light of climate change. Trees invest carbon into specialised metabolism to produce defence compounds against biotic invaders; processes that are strongly affected by physiological stress such as drought. Spruce bark contains numerous terpenoid and phenolic substances, which are important for bark beetle aggregation and attack success. Abiotic stressors such as increased temperatures and drought affect composition, amounts and emission rates of volatile compounds. Thus, drought events may influence olfactory responses of I. typographus, and further the pheromone communication enabling mass attack. In addition, I. typographus is associated with numerous ophiostomatoid fungal symbionts with multiple effects on beetle life history. Symbiotic fungi degrade spruce toxins, help to exhaust tree defences, produce beetle semiochemicals, and possibly provide nutrition. As the various fungal associates have different temperature optima, they can influence the performance of I. typographus differently under changing environmental conditions. Finally, we discuss why effects of drought on tree-killing by bark beetles are still poorly understood and provide an outlook on future research on this eruptive species using both, field and laboratory experiments.

Seed consumption by rodents causes substantial economic losses in agriculture and forest restoration. Rodents rely on their sensitive sense of smell to gather information about their environment. However, comparably little is known about how rodents use olfaction to locate food. We used bank voles to measure attraction to acorn odors in a Y-maze. Preferences were measured using two behaviors: approaching (time spent in odor preference zones) and investigation (numbers of nose pokes in odor nozzle), which yielded similar results. Shorter time intervals (15 and 30 s) in the preference zones were at least as good as the longer time interval (60 s) for detecting differences in approaching behavior. In this way, it is possible to reduce the measurement time with approximately 50%. Investigation, which was evaluated using only one time interval (180 s), yielded longer measurement time. Acorns were as preferred as the familiar, standard food (rodent chow) while an acorn aeration extract did not produce any response. We conclude that short measurement times for the evaluation of attractive odors makes it possible to efficiently assay the wide range of volatile compounds from bank voles’ natural foods which may be important in studies wishing to develop new rodent control methods.

Key message The dog detection allows timely removal by sanitation logging of first beetle-attacked trees before offspring emergence, preventing local beetle increases. Detection dogs rapidly learned responding to synthetic bark beetle pheromone components, with known chemical titres, allowing search training during winter in laboratory and field. Dogs trained on synthetics detected naturally attacked trees in summer at a distance of > 100 m. Context An early detection of first beetle-attacked trees would allow timely sanitation felling before offspring emergence, curbing local beetle increase. Aims We tested if detection dogs, trained off-season on synthetic pheromone components from Ips typographus, could locate naturally bark beetle–infested spruce trees. Methods Indoor training allowed dogs to discriminate between the infestation odours (target) and natural odours (non-target) from the forest. Odour stimuli were shown by chemical analysis to be bioactive at extremely low-levels released (−4 ng/15 min) in the laboratory. Results Detection dogs, trained to recognise four different synthetic pheromone compounds in the wintertime, were able to detect naturally infested spruce trees unknown to humans the following summer. The dog-handler pairs were able to detect an infested spruce tree from the first hours of beetle attack until several weeks after first attack, long before discolouration of the crown. Trained sniffer dogs detected infested spruce trees out to ≥ 100 m, as measured by GPS-collar tracks. Conclusion Dog-handler pairs appear to be more efficient than humans alone in timely detecting bark beetle infestations due to the canine’s ability to cover a greater area and detect by olfaction infestations from a far longer distance than can humans.

Bark beetles kill apparently vigorous conifers during epidemics by means of pheromone-mediated aggregation. During non-endemic conditions the beetles are limited to use trees with poor defense, like wind-thrown. To find olfactory cues that help beetles to distinguish between trees with strong or weak defense, we collected volatiles from the bark surface of healthy felled or standing Picea abies trees. Furthermore, living trees were treated with methyl jasmonate in order to induce defense responses. Volatiles were analyzed by combined gas chromatography and electroantennographic detection (GC-EAD) on Ips typographus antennae. Compounds eliciting antennal responses were characterized by single sensillum recording for identification of specific olfactory sensory neurons (OSN). Release of monoterpene hydrocarbons decreased, while oxygenated compounds increased, from spring to early summer in felled trees. In both beetle sexes particular strong EAD activity was elicited by trace amounts of terpene alcohols and ketones. 4-Thujanol gave a very strong response and the absolute configuration of the tested natural product was assigned to be (+)-trans-(1R,4S,5S)-thujanol by stereoselective synthesis and enantioselective gas chromatography. One type of OSN responded to all ketones and five other OSN were characterized by the type of compounds that elicited responses. Three new OSN classes were found. Of the eight EAD-active compounds found in methyl jasmonate-treated bark, the known anti-attractant 1,8-cineole was the one most strongly induced. Our data support the hypothesis that highly active oxygenated host volatiles could serve as positive or negative cues for host selection in I. typographus and in other bark beetles.

Restoration of mixed oak forest in northern temperate regions is important for biodiversity and for adaptation of forest management to climate change. Direct seeding has been considered as a cost-effective method for the assisted regeneration of oaks. However, removal of acorns by granivorous rodents hinders its application. Patterns of acorn removal can vary with habitat type, presence of predators, and acorn size. In this field study, we tested the effects of distance to forest edge, predator excrement as a repellent, and acorn size on the performance of direct-seeded oak in southern Sweden. The experiment was carried out at two different sites. Our hypotheses were: (i) in clear-cuts, acorn removal is higher closer to the forest edge compared to open areas, (ii) treatment with predator excrement reduces acorn removal without affecting germination, and (iii) larger acorns will be removed more readily than smaller acorns. Finally, we also investigated if seedlings from larger acorns survive better and grow taller compared to smaller acorns in relation to habitat structure and predator excrement as repellent. Acorn removal differed at the two sites. At Skrylle (older clear-cut), no forest edge effects were found. At Klaverod (new clear-cut site), our results suggest that removal of acorns was higher in the open clear-cut due to the presence of large slash piles. Less vegetation coverage correlated with lower rates of acorn removal, except near slash piles. Our results therefore suggest that forest managers should reduce understory vegetation and avoid slash piles during direct seeding of oak. Mink excrement failed to protect acorns against removal, but did not reduce acorn germination. Bigger acorns produced taller seedlings but did not enhance overall woodland establishment due to their higher removal rate. Our results further suggest a potential food satiation effect due to an extra supply of additional food. Satiation manipulation might potentially be a method of mitigating the impact of seed predation by granivorous rodents during the direct seeding of oak, but such an approach requires further research before it could be recommended.

The onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a polyphagous pest that causes serious damage to agricultural crops, vegetables, and ornamental plants worldwide. Farmers rely on the extensive usage of synthetic chemical insecticides to control T. tabaci. There is a dire need to develop alternative control strategies to overcome the problems posed by chemical insecticides. Efficient traps would allow sensitive monitoring and possibly mass trapping. A field experiment was conducted to evaluate the potential of three plant compounds with known release rates (ranging from 6-30 mg/d); eugenol (Eug), 1, 8-cineole (eucalyptol), and linalool in all possible combinations with a thrips attractant, ethyl iso-nicotinate (EI). A combination of EI with Eug increased the effect of EI by attracting 100% more thrips (effect size, 1.95) as compared to the control of EI alone. Catches in remaining treatments were lower and or not significantly different from EI alone. The results from our study could be used to develop improved volatile blends to be used for monitoring traps. Our data suggests that these traps could be effective even at very low populations.

In this proof of concept study, we report the off season training of two detection dogs on a series of synthetic semiochemicals associated with Ips typographus pest bark beetle infestations of spruce trees. Scent detection training allowed dogs to discriminate between physiologically-relevant infestation (target) odours, quantified by GC-MS using extracted ion chromatogram to be bio-active at levels of < 10−4 ng /15 min or lower, and natural non-target odours that might be encountered in the forest. Detection dogs trained to recognize four different synthetic pheromone compounds in the winter time, well before beetle flight, were able to detect natural infested spruce trees unknown to humans the following summer. The trained detection dogs were able to detect an infested spruce tree from the first hour of bark beetle attack until several weeks after the attack. Trained detection dogs appear to be more efficient than humans in detecting early bark beetle infestations because the canines ability to cover a greater area and by olfaction detect infestations from a far greater distance than can humans. Infested spruce trees could be detected by trained detection dogs out to more than 100 m.Key MessageDetection dogs were rapidly trained to locate release of synthetic bark beetle pheromone componentsSynthetics allowed dog training off-season both in laboratory and fieldDogs trained on synthetics detected naturally target pest insect attacked trees at a distance of more than 100 m.The method allows rapid removal of single, first attacked trees before offspring emergence, thus curbing local pest increase and lowering spread of attacks in the landscap

Taxi Stockholm is a Swedish taxi company which would like to improve their mobile phone application with a destination prediction feature. This thesis has created an algo- rithm which predicts a destination to which a taxi customer would like to go. The problem is approached using the KDD process and data mining methods. A dataset consisting of previous taxi rides is cleaned, transformed, and then used to evaluate the performance of three machine learning models. More specifically a neural network model paired with K- Means clustering, a random forest model, and a k-nearest neighbour model. The results show that the models that were developed in this thesis could be used as a first step in a destination prediction system. The results also show that personal data increase the accu- racy of the neural network model and that there exists a threshold for how much personal information is needed to increase the performance.

Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsi- ble nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I. shangrila and I. nitidus, are typi- cal in this regard. Six synthetic candidate pheromone compo- nents that we earlier identified from hindguts of unmated males of these two Ips species were tested for field activity in Qinghai province, P. R. China. For I. nitidus, racemic ipsdienol ((±)-Id) could replace the naturally-produced blend of enantiomers containing 74 % (-)-(S)-Id (74:26 S:R), in attractive ternary or binary blends. In contrast, sympatric I. shangrila were attracted mainly to blends including Id of opposite chirality, 97 %-(+)-(R)-Id. Of the verbenols, (-)- trans-verbenol was inactive for I. nitidus or inhibitory for I. shangrila ,b ut ( -)-cis-verbenol (cV) was a key component of the pheromone in both species. Two fully factorial experiments demonstrated that (±)-Id, cV, and 2-methyl-3- buten-2-ol (MB) are components of the aggregation phero- mone of I. nitidus, whereas only (+)-Id and cV are essential components of the aggregation pheromone of I. shangrila. While MB is not necessary for attraction of I. shangrila ,i t is an active antagonist and likely functions in species isolation. A review of the pheromone production and responses in Pa- learctic Ips and Pseudoips showed that cV is more common than methylbutenols, and both elicit qualitatively variable re- sponses. Ipsdienol is the most common component with var- iable chirality, and is a necessary, but often not sufficient, factor for determining pheromone specificity.

Insects detect their hosts or mates primarily through olfaction, and olfactory receptors (ORs) are at the core of odorant detection. Each species has evolved a unique repertoire of ORs whose functional properties are expected to meet its ecological needs, though little is known about the molecular basis of olfaction outside Diptera. Here we report a pioneer functional analysis of a large array of ORs in a lepidopteran, the herbivorous pest Spodoptera littoralis. We demonstrate that most ORs are narrowly tuned to ubiquitous plant volatiles at low, relevant odorant titres. Our phylogenetic analysis highlights a basic conservation of function within the receptor repertoire of Lepidoptera, across the expansive evolutionary radiation of different major clades. Our study provides a reference for further studies of olfactory mechanisms in Lepidoptera, a historically crucial insect order in olfactory research., The range of odours that an insect can detect depends on its olfactory receptors. Here, the authors functionally characterize the olfactory receptor repertoire of the moth Spodoptera littoralis using the Drosophila empty neuron system and reconstruct the evolution of these receptors in the Lepidoptera.

Phytophagous insects use blends of volatiles released from plants to select hosts for feeding and oviposition. To behaviorally analyze complex blends, we need efficient and selective methods for elucidating neuron types, their ligands, and specificity. Gas chromatography-combined single sensillum recordings (GC-SSRs) from antennal olfactory sensilla of female moth, Spodoptera littoralis revealed 38 physiologically active peaks in the headspace volatile blends from both larvae-damaged cotton plants and lilac flowers. Using GC-combined mass spectrometry, 9 new physiologically active compounds were identified from damaged cotton and 11 from lilac compared with earlier electrophysiological studies using antennae of female S. littoralis. We characterized 14 novel classes of olfactory sensory neurons (OSNs). Among these, we found the first 2 ligands for a frequent type of short trichoid sensillum, for which no ligands were identified earlier. By using GC-SSR, a substantial increase in functional classes of OSNs and active compounds, 40% and 34% more, respectively, compared with recent studies using GC-electroantennogram or SSR using single compounds was detected. Compared with the estimated number of corresponding antennal olfactory receptors, the OSN classes now correspond to 83% of a likely maximum. The many specialist OSNs observed may facilitate behavioral confirmation of key plant volatiles in blends.

The leopard moth Zeuzera pyrina L. (ZP) is an invasive pest from Europe of increasing significance in North Africa, in particular for olive cultivation. We followed the temporal dynamics by combined light/pheromone trapping over a 10-year period (2002–2011) in a 240-ha olive farm in Northern Egypt. The ZP had an annual cycle with one or two peak flights, from late April until October. Time series analysis showed a 2-year cycle of trap catch. This cycle is likely related to the ‘on/off’ bearing pattern of the olive, where years of high and low yield are observed to alternate. Larval damage in both ‘on’ and ‘off’ years in the infested trees gave fruit yield losses of 37–42%. The loss was estimated to 2.1–4.8 t/ha among susceptible varieties. The relative losses were the same during on and off years. Infestation of four susceptible and five resistant olive cultivars in different cropping systems varied within and between adjacent plots. The results suggest less infestation by intercropping of resistant varieties, which could assist in ZP management. Both temporal and spatial dynamics strongly influence population dynamics and the dynamics are related to variation in the moth host plant.

The effects of the oviposition regime on egg maturation rate in the synovigenic parasitoid, Microplitis rufiventris Kokujev were investigated. In non-ovipositing wasps, females normally reach a peak of egg maturation rate on 1 d posteclosion. Egg maturation slowed down once the maximum oviduct egg load was reached on 2 d posteclosion. In wasps manipulated for 20 ovipositions per day, the egg maturation rate during the first 3 d posteclosion was lower compared with those manipulated for 40 ovipositions per day. The rate of egg maturation in 1-d-old wasps was found to be the highest for those that experienced 60 ovipositions per day. The maturation rate in females offered unlimited hosts was not significantly greater than those manipulated for 40 ovipositions per day. The act of oviposition significantly increased the rate of egg maturation and minimized egg resorption in the female wasp. The distribution of mature eggs in the ovaries at death is apparently associated with the oviposition regime. Trade-offs between egg maturation rate and female longevity were quite evident.

1. The sense of smell is crucial for fitness of most animals, enabling them to find mates, food and egg laying sites and to stay away from danger. Hence, odour molecules are detected by sensitive and specific olfactory sensory neurons (OSNs). In insects, the OSNs are stereotypically grouped into olfactory sensilla located mainly on the antennae. The functional significance of this co-localization principle is poorly understood, but it has been hypothesized that it allows for coincidence detection of odour filaments, improving discrimination of closely separated odour sources. 2. Using an insect in its natural environment, we conducted the first experimental test of the hypothesis. We manipulated the distance between odour sources of an attractive pheromone and either of two host-derived attraction antagonists (1,8-cineole and verbenone) and investigated the effect on trap catches of the bark beetle, Ips typographus (Coleoptera). 1,8-Cineole is detected by an OSN co-localized with an OSN for one of the pheromone components, while verbenone is detected by OSNs in other sensilla, not co-localized with pheromone OSNs. 3. Consistent with the hypothesis, trap catch increased with distance between odour sources more for 1,8-cineole than for verbenone. The strongest effect was found among the males, that is the sex that first locates and attacks the host tree. 4. Our data from the beetle provide, for the first time, direct experimental support for the hypothesis that co-localization of OSNs in sensilla improves the discrimination of closely separated odour sources. Thus, selection for improved odour source discrimination could well be one of the factors explaining the strict co-localization of OSNs that is seen across the Insecta class. (Less)

In order to locate mates, food, and oviposition sites, insects mainly rely on volatile cues released by their sexual partners, food sources, and host and non-host plants. Calling, mating, and oviposition behaviors, as well as fecundity and longevity, of newly emerged Spodoptera littoralis (Bois.) moths were recorded in the presence of volatiles from leaves of a host plant, Gossypium hirsutum (cotton) and two non-host plants, Adhatoda vasica (Av) or Picea abies (spruce), either alone or in host/non-host combinations. Females exposed to cotton volatiles started calling earlier than females exposed to non-host plant volatiles (NHV), or the blank control. Likewise, moth pairs exposed to cotton volatiles started mating earlier than the other treatments. The period of calling in females alone was longer than females kept with males, having the opportunity to mate. However, the callings, as well as mating durations in the moth pairs, in different treatments were not different. Longevity was decreased either in the absence of cotton or the presence of Av, and spruce leaves. Fecundity was reduced in moths exposed to a combination of spruce and cotton. The effect of NHV on attraction of 2-3-day-old male moths towards a pheromone (Ph) source was studied in a wind tunnel. In the no-choice assay, more males arrived at close approach and landed on the Ph source when the host plant, cotton, was offered in the background as compared to the non-hosts. In the dual-choice assay, more males landed on the Ph source in front of the host plant compared to the Ph source in front of non-hosts. Gas chromatography-electroantennographic detection on female S. littoralis revealed five antennally active compounds in headspace collections of spruce and three compounds in Av.

The number of mature eggs carried by a female parasitoid at any given moment (egg load) is a fitness-related parameter affecting reproductive potential and impacting upon host population dynamics. Microplitis rufiventris Kokujev (Hymenoptera: Braconidae) is a solitary koinobiont endoparasitoid wasp of several noctuid pests, including Spodoptera littoralis. The number of mature eggs carried by females at emergence is approximately 50. The rate of egg maturation is strongly affected both by feeding status and access to host larvae. In early adult life, egg maturation rates are lower for 6–72 h in fed wasps compared with food-deprived wasps. When given access to hosts, honey-fed wasps live for approximately 9 days with high lifetime fecundity (226 eggs). By contrast to early adult life, the total realized fecundity is positively affected by feeding status, where water-fed and starved females have 140 and 107 eggs, respectively. Egg resorption is most pronounced in the later life of females. The results suggest, in addition to confirming the effect of honey-feeding on total fecundity, that fecundity of starved wasps includes rapid egg maturation early in life, which potentially could improve the performance of the parasitoid as a biological control agent.

Bark beetles face challenges and trade-offs during host selection, imposed by lethal tree defences, lower nutrition and higher competition in less well-defended trees, scarcity and ephemeral distribution of susceptible hosts, limitation of suitable hosts to one beetle generation, and relatively short lifespan and vulnerability of adults during host searching. Beetles contend with these challenges by using multiple, integrated sensory modalities, and sequential decision making. They incorporate both negative and positive information at multiple scales to locate susceptible hosts across large and heterogeneous landscapes. Some of the olfactory sensory neurons that convey non-host signals are relatively broadly tuned, whereas those that underlie intraspecific communication and host quality assessment are more specific, an arrangement that maximizes the use of antennal space while retaining high fidelity of detection channels strongly linked to survival and reproduction. The pertinent co-localization of neurons within sensilla provides the means for odour mixture processing in the periphery and enhances odour source discrimination and evaluation of chemical ratios in host tissue. Bark beetles show high behavioural plasticity in their orientation sequences, which allows them to adjust to environmental variability. This plasticity is modulated by environmental, genetic, and gene × environment drivers. Behavioural plasticity allows individuals to best realize the benefits that can be derived from pheromone-mediated cooperative attacks when populations are high. Cross-scale linkages among neurons, sensilla, orientation sequences, populations, and habitat structure underlie the landscape-scale environmental and socioeconomic impacts bark beetles exert. They also underlie rapid outbreaks in response to human-induced environmental alterations, such as climate change, habitat manipulation, and global transport.

Jasmine moth (JM), Palpita unionalis (Hubner) (Lepidoptera: Pyralidae) is a very important pest in the commercial, densely planted olive orchards in Egypt. In years of its highest population density, it can destroy a significant part of the crop. The objectives of this study were to determine the male flight trend and egg laying trend of the JM in three large plots of different olive varieties (two varieties/plot) in two successive fruiting seasons. Differences in male flight trend and egg laying trend of JM were observed among the different varieties (‘Sennara’, ‘Toffahi’, ‘Shamy’). In 2003, more males were captured in traps placed in the Sennara/Toffahi plot than in the two Shamy/Toffahi plots. Egg densities were higher on Toffahi trees grown between Sennara trees than on Toffahi trees grown between Shamy ones. In 2004, in the plot where Toffahi and Sennara were grown together, JM females laid more eggs than in the olive plot where Toffahi rows alternated with Shamy rows. The results suggest that the Shamy variety discouraged gravid females from ovipositing, compared with Toffahi or Sennara varieties. In conclusion, olive variety, cropping system (mixed culture) and trapping season are among those characteristics that affect this pest.

In natural spruce stands, a change of generation is usually initiated by wind or bark beetle disturbances. We combined semi-temporary monitoring plots, remote sensing, and GIS in order to understand and model these processes. Sub plots, called “active”, were located in areas with a high probability of bark beetle or wind disturbances. The optimal location of these plots is usually at an active forest edge, i.e., the zone of maximal change in bark beetle abundance over time, corresponding to the border between wind-damaged or bark beetle-attacked parts and undisturbed parts of a forest stand. The key variable investigated was tree mortality caused by bark beetles. Other variables were similar to those recorded in traditional forest monitoring. Tree defense indicators (resin flow, phenolic compounds) and reaction of a tree to bark beetle inoculation were measured. Terrestrial data were then combined with remote sensing data. Time series of satellite images were analyzed in order to define the pattern of wind and bark beetle damages. Weather monitoring data were used for predicting bark beetle and water stress development. All of the information was integrated in a GIS-based system and future bark beetle infestations were predicted. In this paper, we review previous studies and conclude that: (1) the hypotheses of habitat selection (non-host volatiles and semiochemical diversity) and location of moderately-stressed host trees are confirmed, although further work about olfactory orientation and host resistance is needed;(2) reactions of trees to bark beetle attack can be predicted by monitoring several parameters, e.g., air temperature and tree physiology; (3) data from ground monitoring can be integrated with GIS and remote sensing systems for bark beetle prognosis and management at the habitat and landscape levels.

BACKGROUND: Polysubstance use is common in substance users, and may complicate their clinical course. This study, in a criminal justice setting in Sweden, examines the association between the number of concurrently used substance types and psychiatric symptoms during 30 days before incarceration, while controlling for background variables such as family history (drug and alcohol problems, psychiatric problems, criminality), demographic data and history of emotional, physical or sexual abuse. METHODS: The data material comprised 5659 criminal justice clients reporting a substance use problem, examined with the Addiction Severity Index. Variables were compared in a multinomial regression analysis, comparing clients reporting one (n=1877), two (n=1408), three (n=956), four (n=443) and five or more (n=167) substance types. RESULTS: The 30-day prevalence of most psychiatric symptoms included in the study (depression, anxiety, cognitive problems, hallucinations, difficulty controlling violent behaviour, suicidal ideation, suicide attempts) was higher in individuals with a higher number of concurrent substance types used. In multinomial regression analysis, while controlling for background variables, these associations remained for concurrent suicidal ideation, cognitive problems, hallucinations and violent behaviour, with the latter two being associated with the higher numbers of substance types. Binge alcohol drinking, tranquilizers, opioids and the number of substance types reported were associated with several of the psychiatric symptoms. CONCLUSIONS: In the present criminal justice setting in Sweden, the use of multiple substance types and concurrent psychiatric symptoms appear to be associated, and a sub-group reporting particularly high numbers of concurrent substance types are particularly likely to report potentially severe psychiatric problems.

Orientation for insects in olfactory landscapes with high semiochemical diversity may be a challenging task. The partitioning of odor plumes into filaments that are interspersed with pockets of 'clean air' may help filament discrimination and upwind flight to attractive sources in the face of inhibitory signals. We studied the effect of distance between odor sources on trap catches of the beetle, Ips typographus, and the moth, Spodoptera littoralis. Insects were tested both to spatially separated pheromone components [cis-verbenol and 2-methyl-3-buten-2-ol for Ips; (Z,E)-9,11-tetradecadienyl acetate and (Z,E)-9,12-tetradecadienyl acetate for Spodoptera], and to separated pheromone and anti-attractant sources [non-host volatile (NHV) blend for Ips; (Z)-9-tetradecenyl acetate for Spodoptera]. Trap catch data were complemented with simulations of plume structure and plume overlap from two separated sources using a photo ionization detector and soap bubble generators. Trap catches of the beetle and the moth were both affected when odor sources in the respective traps were increasingly separated. However, this effect on trap catch occurred at smaller (roughly by an order of magnitude) odor source separation distances for the moth than for the beetle. This may reflect differences between the respective olfactory systems and central processing. For both species, the changes in trap catches in response to separation of pheromone components occurred at similar spacing distances as for separation of pheromone and anti-attractant sources. Overlap between two simulated plumes depended on distance between the two sources. In addition, the number of detected filaments and their concentration decreased with downwind distance. This implies that the response to separated odor sources in the two species might take place under different olfactory conditions. Deploying multiple sources of anti-attractant around a pheromone trap indicated long-distance (meter scale) effects of NHV on the beetle and a potential use for NHV in forest protection.

Laboratory experiments were conducted to determine the effect of host instar and feeding status on the egg load of early life stage in Microplitis rufiventris Kokujev (Hymenoptera: Braconidae), a solitary koinobiont endoparasitoid of some noctuid pests. The wasps that developed from fourth or fifth instars of Spodoptera littoralis (Boisduval) larvae were heavier in weight than those from earlier stages. Different numbers of mature eggs were found in the two ovaries of the female wasp. Egg loads, corresponding to fitness, were significantly influenced by female weight and feeding status. However, the interactions between the two treatment factors were not significant. The average number of mature eggs carried by females at eclosion time ranged from 52 eggs in smaller wasps to 62 eggs in larger wasps. Females that were fed had higher egg loads and egg maturation rate than unfed females. However, female wasps were capable of maturing considerable number of eggs without feeding; suggesting that they produce a certain portion of eggs from nutritional reserves that had been stored during larval stage. Female wasps are weakly synovigenic, with an egg maturation at a rate of ≈1.8 eggs per h. Further investigation is required to verify the rate of egg maturation and eventually egg resorption in different stages of adult female M. rufiventris.

Stereoisomers of 4-methyl-3-heptanol (MH) are pheromone components of several Scolytus bark beetles. The elm bark beetle Scolytus laevis (Coleoptera: Scolytidae) has in previous studies been caught in traps baited with commercial MH containing all four stereoisomers, but the lure has been considered a weak attractant. In this study, we addressed the question whether stereospecific responses by S. laevis to stereoisomers of MH might contribute to its niche separation from other sympatric Scolytus species. Using GC–MS, we analyzed extracts of hindguts and abdomens from male and female S. laevis and the sympatric S. triarmatus. We also tested all four MH-stereoisomers individually and in combinations in the field to determine their role for S. laevis. All four stereoisomers were synthesized via a boronic ester method with 1,2-dicyclohexylethanediol as chiral director. In addition, the (3S,4R)-stereoisomer of MH was prepared through enantioselective, lipase-mediated transesterification of a mixture of the four stereoisomers of MH. Females of both species contained small amounts of syn-MH, and males contained trace amounts of anti-MH. The anti stereoisomer (3R,4S)-MH was attractive to male and female S. laevis, whereas the syn stereoisomer (3S,4S)-MH acted as an inhibitor or deterrent and reduced the catch when added to the attractive isomer. The syn isomer is the main aggregation pheromone component of the larger and sympatric S. scolytus and possibly also of S. triarmatus. The avoidance response of S. laevis to the (3S,4S)-stereoisomer may reduce interspecific competition for host trees.

Background: The present study examines a population of criminal justice clients for suspected substance-related problems. Aims: It aims to identify variables associated with a history of suicide attempt (SA). Method: 6,836 clients were interviewed with the Addiction Severity Index (ASI). Attempters were compared to nonattempters regarding substance use, medical/psychiatric status, family history, and social relationships in a stepwise forward logistic regression. Results: Attempters (21%) were more likely to report binge drinking, intake of illicit drugs, injection of drugs, physical and mental illness, problematic family history, and history of being abused. After logistic regression, SA was independently associated with older age, female gender, binge drinking, delirium tremens, injection, overdose, medical problems, psychiatric symptoms, family history of alcohol or psychiatric problems, and sexual, physical, and emotional abuse. The psychiatric and family/social domains (including being abused) most strongly separated attempters from nonattempters. Conclusions: Family background factors, psychiatric symptoms, severity of substance use, and sexual, physical, and emotional abuse appear to be factors associated with SA among criminal justice clients.

BACKGROUND: Field trapping experiments were carried out to evaluate effective trap characteristics for maximising Ips duplicatus(Sahlberg) catches in pheromone-baited traps in China. RESULTS: Window-slot and cross-barrier traps had significantly higher catches than multiple-funnel traps. The colour of window-slot traps showed a significant effect on catches, with dark colours (black and red) being more effective than light colours, especially white and yellow. Window-slot traps at a 1.5‐2.0 m level caught more beetles than those at either ground level (0‐0.5 m) or at 3.5‐4.0 m. Ips duplicatus can be attracted to pheromone-baited traps over a distance of >100 m from the forest edge in an open grassy field. There was a strong diurnal pattern of flight activity, with catches on window-slot traps occurring during the daytime with one broad peak at mid- to late afternoon. The seasonal flight activity of I. duplicatus as monitoredbypheromone-baitedwindow-slottrapsduring2007‐2008indicatedthatthreemajorflightpeaksoccurredinearly June, late June‐early July and late July respectively, suggesting the existence of a potential second generation. CONCLUSION:Theoptimaltrapcharacteristicswillimprovetheperformanceofpheromone-baitedtrapsasacriticalmonitoring or mass-trapping tool to combat outbreaks of this pest species. c � 2009 Society of Chemical Industry

We screened 150 olfactory sensilla in single-sensillum recordings to unravel the mechanisms underlying host selection in the spruce bark beetle, Ips typographus (Coleoptera: Curculionidae: Scolytinae). Odor stimuli comprised of pheromone (various bark beetle spp.), host, and non-host compounds elicited strong and selective responses from 106 olfactory receptor neurons (ORNs), 45 of which were tuned to pheromone compounds, 37 to host compounds, and 24 to non-host volatiles (NHV). In addition, 26 ORNs responded only weakly to any odor stimulus. Strongly responding ORNs were classified into 17 classes. Seven classes responded primarily to the Ips pheromone compounds: cis-verbenol, ipsenol, ipsdienol (two classes), 2-methyl-3-buten-2-ol, amitinol, or verbenone, respectively. Six classes responded to the host compounds: alpha-pinene, myrcene, p-cymene, myrcene and p-cymene, 1,8-cineole, or Delta3-carene, respectively. Four classes responded to NHV: 3-octanol, 1-octen-3-ol, trans-conophthorin, or indiscriminately to the repellent green leaf volatiles (GLVs) 1-hexanol, Z3-hexen-1-ol and E2-hexen-1-ol, respectively. Indiscriminate responses from GLV neurons might explain a behavioral redundancy among these GLVs. This is the first description of individual bark beetle ORNs dedicated to NHV perception. These comprise almost 25% of the strongly responding neurons, demonstrating that a large proportion of the olfactory system is devoted to signals from plants that the insect avoids.