| 1. |
- Köhler, Elof, 1980, et al.
(författare)
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Impact of designed asymmetries on the effective bandwidth of a backfolded piezoelectric energy harvester
- 2019
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Ingår i: Sensors and Actuators, A: Physical. - : Elsevier BV. - 0924-4247. ; 292, s. 77-89
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Tidskriftsartikel (refereegranskat)abstract
- For the successful realization of autonomous wireless sensors, they will have to be able to harvest energy from their surroundings. Vibrational energy harvesting is one possible power source for wireless sensors, since vibrations are abundant in many environments. In order to make vibrational energy harvesters more useful, a broad bandwidth is desirable since many vibrations are stochastic in nature. In this paper we implement asymmetry to a backfolded piezoelectric energy harvester to achieve broader effective bandwidth with maintained power output. The optimized harvester achieves a minimum of 2.75 V in the frequency range 92–162 Hz with peak power output of 1.80 mW. Asymmetry based on different lengths of the conjoined cantilevers is experimentally and numerically shown to have the largest impact on the bandwidth, compared to the impact of modified mass loadings.
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| 2. |
- Martel, Véronique, et al.
(författare)
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Mosquito Feeding Affects Larval Behaviour and Development in a Moth
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Organisms are attacked by different natural enemies present in their habitat. While enemies such as parasitoids and predators will kill their hosts/preys when they successfully attack them, enemies such as micropredators will not entirely consume their prey. However, they can still have important consequences on the performance and ecology of the prey, such as reduced growth, increased emigration, disease transmission. In this paper, we investigated the impact of a terrestrial micropredator, the yellow fever mosquito Aedes aegypti, on its unusual invertebrate host, the Egyptian cotton leaf worm, Spodoptera littoralis. Larvae developing in presence of mosquitoes showed a slower development and reached a smaller pupal weight when compared to a control without mosquitoes, apparently because of a reduced feeding time for larvae. In addition, larvae tended to leave the plant in presence of mosquitoes. These results suggest that mosquitoes act as micropredators and affects lepidopteran larvae behaviour and development. Ecological impacts such as higher risks of food depletion and longer exposure to natural enemies are likely to be costly consequences. The importance of this phenomenon in nature - the possible function as last resort when vertebrates are unavailable - and the evolutionary aspects are discussed.
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| 3. |
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| 4. |
- Nilsson, Ulf, et al.
(författare)
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Comparison of nectar use and preference in the parasitoid Trybliographa rapae (Hymenoptera: Figitidae) and its host, the cabbage root fly, Delia radicum (Diptera: Anthomyiidae)
- 2011
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Ingår i: Biocontrol Science and Technology. - : Informa UK Limited. - 0958-3157 .- 1360-0478. ; 21, s. 1117-1132
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated differences in flower preferences between the parasitoid Trybliographa rapae Westwood (Hymenoptera: Figitidae) and its host, the economically important pest of cruciferous crops, the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). The data obtained were used to suggest selective food plants in conservation biological control programmes for control of D. radicum. The attraction of both insect species to floral odours emitted from nine different plant species, their ability to access nectar from four of these species and the effect of the most promising plant species on insect longevity were determined. Naive T. rapae females were significantly attracted to flower odours from Fagopyrum esculentum Moench. (Polygonaceae) and repelled by Coriandrum sativum L. (Apiaceae) and Borago officinalis L. (Boraginaceae). In addition, T. rapae gained weight when exposed to F. esculentum, Anethum graveolens L. (Apiaceae) and Lobularia maritima Desv. (Brassicaceae). In contrast, naive D. radicum females showed attraction to most of the flowers. The longevity of both T. rapae and D. radicum increased significantly when they were provided with flowering A. graveolens and F. esculentum. In addition to the laboratory studies, a semi-field experiment was made to study the impact of flowering F. esculentum on the ability of T. rapae to parasitise D. radicum larvae. Significantly more larvae were parasitised in cages where a floral resource was present. The findings are discussed in the context of a Brassica agroecosystem.
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| 5. |
- Anderson, Peter, et al.
(författare)
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Does Host Size and Feeding Status Influence the Egg Load of Microplitis rufiventris (Hymenoptera: Braconidae)?
- 2011
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Ingår i: Annals of the Entomological Society of America. - 0013-8746. ; 104, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- 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 approximate to 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.
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| 6. |
- Anderson, Peter, et al.
(författare)
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Root herbivory affects oviposition and feeding behavior of a foliar herbivore
- 2011
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 22, s. 1272-1277
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Tidskriftsartikel (refereegranskat)abstract
- Performance and distribution of phytophagous insects are driven by direct and indirect competitive interactions. Plant-feeding arthropods have been shown to interact indirectly through the plants' response to herbivory. In the case of systemically induced plant responses, this interaction extends to herbivores inhabiting different parts of a plant, for example, above- and belowground herbivores. Plant-induced responses elicited by root herbivores have been shown to affect feeding and development of aboveground herbivores. However, little is known about how root feeding affects host choice behavior of aboveground herbivores, including both adult oviposition behavior and larval host acceptance. Here, we report that root feeding by the wireworm, Agriotes lineatus, influences oviposition decisions and larval leaving rate of an aboveground herbivore, Spodoptera littoralis. In choice experiments, female S. littoralis deposited more and larger egg batches on undamaged plants when compared with wireworm-infested plants. In a larval feeding experiment, a higher percentage S. littoralis larvae moved away from the wireworm-infested plant onto a neighboring undamaged plant as compared with larvae feeding on previously undamaged plants. Larvae did not show an increased tendency to leave when feeding on plants previously exposed to conspecific larvae. Our results show that indirect interactions between belowground and aboveground herbivores extend to behavioral avoidance, both in terms of oviposition and larval feeding decisions. This allows the foliar herbivore to avoid systemic plant responses elicited by root herbivory, which likely represent reduced food quality and increased apparency toward natural enemies.
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| 7. |
- Abreha, Kibrom Berhe, et al.
(författare)
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Inoculation of Transgenic Resistant Potato by Phytophthora infestans Affects Host Plant Choice of a Generalist Moth
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Pathogen attack and the plant's response to this attack affect herbivore oviposition preference and larval performance. Introduction of major resistance genes against Phytophthora infestans (Rpi-genes), the cause of the devastating late blight disease, from wild Solanum species into potato changes the plant-pathogen interaction dynamics completely, but little is known about the effects on non-target organisms. Thus, we examined the effect of P. infestans itself and introduction of an Rpi-gene into the crop on host plant preference of the generalist insect herbivore, Spodoptera littoralis (Lepidoptera: Noctuidae). In two choice bio-assays, S. littoralis preferred to oviposit on P. infestans-inoculated plants of both the susceptible potato (cv. Desiree) and an isogenic resistant clone (A01-22: cv. Desiree transformed with Rpi-blb1), when compared to uninoculated plants of the same genotype. Both cv. Desiree and clone A01-22 were equally preferred for oviposition by S. littoralis when uninoculated plants were used, while cv. Desiree received more eggs compared to the resistant clone when both were inoculated with the pathogen. No significant difference in larval and pupal weight was found between S. littoralis larvae reared on leaves of the susceptible potato plants inoculated or uninoculated with P. infestans. Thus, the herbivore's host plant preference in this system was not directly associated with larval performance. The results indicate that the Rpi-blb1 based resistance in itself does not influence insect behavior, but that herbivore oviposition preference is affected by a change in the plant-microbe interaction.
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| 8. |
- Anderson, Peter
(författare)
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Brief predator sound exposure elicits behavioral and neuronal long-term sensitization in the olfactory system of an insect
- 2011
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 108, s. 3401-3405
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Tidskriftsartikel (refereegranskat)abstract
- Modulation of sensitivity to sensory cues by experience is essential for animals to adapt to a changing environment. Sensitization and adaptation to signals of the same modality as a function of experience have been shown in many cases, and some of the neurobiological mechanisms underlying these processes have been described. However, the influence of sensory signals on the sensitivity of a different modality is largely unknown. In males of the noctuid moth, Spodoptera littoralis, the sensitivity to the female-produced sex pheromone increases 24 h after a brief preexposure with pheromone at the behavioral and central nervous level. Here we show that this effect is not confined to the same sensory modality: the sensitivity of olfactory neurons can also be modulated by exposure to a different sensory stimulus, i.e., a pulsed stimulus mimicking echolocating sounds from attacking insectivorous bats. We tested responses of preexposed male moths in a walking bioassay and recorded from neurons in the primary olfactory center, the antennal lobe. We show that brief exposure to a bat call, but not to a behaviorally irrelevant tone, increases the behavioral sensitivity of male moths to sex pheromone 24 h later in the same way as exposure to the sex pheromone itself. The observed behavioral modification is accompanied by an increase in the sensitivity of olfactory neurons in the antennal lobe. Our data provide thus evidence for cross-modal experience-dependent plasticity not only on the behavioral level, but also on the central nervous level, in an insect.
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| 9. |
- Anderson, Peter, et al.
(författare)
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Cannibalism and intraguild predation involved in the intra- and inter-specific interactions of the invasive fall armyworm, Spodoptera frugiperda, and lepidopteran maize stemborers
- 2023
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 96, s. 1455-1464
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Tidskriftsartikel (refereegranskat)abstract
- Cannibalism and intraguild predation can play important roles in determining spread and survival or death of organisms which share the same resource. However, the relationship between cannibalism and intraguild predation, and the costs and benefits of such behaviours, is difficult to establish within insect communities, and little is known about how such behaviours are affected by invasive species. The present study was aimed at assessing the interactions between larvae of fall armyworm (Spodoptera frugiperda) and maize stemborers (native to Africa, Busseola fusca, and Sesamia calamistis and native to India, Chilo partellus) in relation to cannibalism and intraguild predation when they utilize the same resource. Experiments involving treatments with either single species of S. frugiperda or any of the stemborers or pairwise species combinations with S. frugiperda were conducted under laboratory conditions. The experimental insect larvae were reared on maize leaves and monitored until the last developmental stage where cannibalism and/or intraguild predation, larval survival, and relative growth rate were recorded. Results of the intraspecific interaction indicated that S. frugiperda exhibited cannibalism to a larger degree than the stemborers species, especially at the late instars. The higher cannibalism trait in S. frugiperda turned, however, to competitive advantage as it led to a higher degree of intraguild predation when they cohabit with stemborer species and allowed FAW to gain a greater relative growth rate. Overall, interactions with FAW are detrimental for stemborer species and may be an important factor to explain the invasive success of S. frugiperda. Such knowledge is essential to understand the mechanisms behind ecological interactions between pests with overlapping niches in the field and in designing successful integrated pest management strategies.
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| 10. |
- Anderson, Peter
(författare)
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Effects of storage in triple-layer hermetic bags on stored field pea grain quality and infestation by the pea weevil, Bruchus pisorum L. (Coleoptera: Bruchidae)
- 2022
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Ingår i: Journal of Stored Products Research. - : Elsevier BV. - 0022-474X .- 1879-1212. ; 95
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Tidskriftsartikel (refereegranskat)abstract
- Field pea is an important pulse crop that plays a key role in human and animal nutrition as well as for soil fertility in many cropping systems. In East Africa, the pea weevil, Bruchus pisorum L. (Coleoptera: Bruchidae), is one of the main biotic production constraints causing considerable loss both in the field and during storage. The storage loss level depends on the number of weevils remaining in the seed after harvest and on the storage facilities and practices of the farmers. To address the storage losses, we evaluated the effectiveness of hermetic triple-layer Purdue Improved Crop Storage (PICS) bags, on stored grain quality and control of pea weevil infestation in Ethiopia. The PICS bag and two currently used farmers' storage practices: polypropylene bag (PP) and polyethylene bag with Actellic dust (PE) were compared. Each bag was filled with 50 kg of field peas, and stored for 5 months. Fewer live adult pea weevils and lower percent grain damage was recorded in PICS and PE bags compared to PP bags along the storage period. Field pea grains stored in PICS bags and PE bag also retained higher germination capacity as compared to those stored in a PP bag. The proximate composition differed significantly between storage treatments during the trial. Grain stored in PICS bag and PE bag with Actellic dust showed higher grain moisture, crude protein, and crude fat content, but less total carbohydrate and ash content as compared with grain stored in PP bag. We concluded that PICS bags can be used by smallholder field pea growers to maintain grain quality postharvest, remove the need to use pesticides on their stored peas, and reduce pea weevil damage.
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