Life history and host specificity ofAltica cyanea [Coleoptera: Chrysomelidae], a potential biological control agent for water primrose,Ludwigia adscendens

The life history and host-specificity of the flea beetle,Altica cyanea (Weber) [Coleoptera: Chrysomelidae], were studied to determine its potential value as a biological control agent for water primrose,Ludwigia adscendens (Onagraceae). Females laid a mean of 146 yellowish eggs in masses on this weed and larvae passed through 3 instars. This multivoltine insect completed a generation in 80–84 days. In preliminary host-specificity trials, larvae and adults fed slightly on 2 varieties ofTrapanatans, but they caused considerable damage toLudwigia spp.; no feeding occurred on rice. In host plant choice tests, larvae and adults preferred to feed onL. adscendens andL. prostata toT. natans. In these same tests, onlyLudwigia spp. supported complete development, but it was fastest onL. adscendens. Adults that were reared onL. adscendens lived longer and laid more eggs than those reared onL. prostata, suggesting thatA. cyanea may be a promising biological control agent forL. adscendens growing in rice-paddies. AdultZicrona coerulea L. [Hemiptera: Pentatomidae] preyed upon 3rd instarA. cyanea larvae in the laboratory.      

Attraction of the biocontrol agent,Lema praeusta,towards two Commelinaceae weed volatiles

Two Commelinaceae weeds, Commelina benghalensis L. and Murdannia nudiflora (L.) Brenan, are abundant in rice fields of India. Larvae and adults of Lema praeusta (Fab.) (Coleoptera: Chrysomelidae) voraciously consume these two weeds. Synthetic herbicides are applied to control both weeds, but applications of these substances have harmful effects in environment and beneficial organisms. So, it is necessary to use native biocontrol agent to control these weeds. Hence, an attempt has been made to find volatile organic compounds (VOCs) from both weeds causing attraction of L. praeusta. Behavioural responses of L. praeusta towards volatile blends from undamaged (UD), insect-damaged (ID: plants after 6 or 48 hr of continuous insect feeding) and mechanically damaged (MD) plants were conducted by Y-tube olfactometer bioassays. Benzyl alcohol was predominant in VOCs of UD plants and M. nudiflora after 48 hr of insect feeding. Benzyl alcohol and cuminaldehyde were both predominant in VOCs of C. benghalensis after 48 hr of insect feeding. Females were more attracted towards volatile blends from plants after 48 hr of insect feeding compared to undamaged plants. Females showed attraction towards a synthetic blend of seven compounds—7.28 µg (Z)-3-hexen-1-ol, 0.93 µg trans-isolimonene, 19.18 µg benzyl alcohol, 0.16 µg undecane, 1.07 µg 1-nonanol, 1.23 µg 1-undecanol and 0.47 µg 1-eicosene resembling the amounts released by C. benghalensis after 48 hr of insect feeding during 1 hr or a synthetic blend of six compounds—18.10 µg benzyl alcohol, 0.25 µg undecane, 0.56 µg 1-nonanol, 1.37 µg 1-undecanol, 0.35 µg 1-eicosene and 2.19 µg phytol resembling the amounts released by M. nudiflora after 48 hr of insect feeding during 1 hr. This study concludes that both blends could be used to attract the biocontrol agent during early vegetative period of these two weeds, which could lead to eradication of weeds from rice fields.     

An ecogenomic analysis of herbivore‐induced plant volatiles in Brassica juncea

Upon herbivore feeding, plants emit complex bouquets of induced volatiles that may repel insect herbivores as well as attract parasitoids or predators. Due to differences in the temporal dynamics of individual components, the composition of the herbivore‐induced plant volatile (HIPV) blend changes with time. Consequently, the response of insects associated with plants is not constant either. Using Brassica juncea as the model plant and generalist Spodoptera spp. larvae as the inducing herbivore, we investigated herbivore and parasitoid preference as well as the molecular mechanisms behind the temporal dynamics in HIPV emissions at 24, 48 and 72 h after damage. In choice tests, Spodoptera litura moth preferred undamaged plants, whereas its parasitoid Cotesia marginiventris favoured plants induced for 48 h. In contrast, the specialist Plutella xylostella and its parasitoid C. vestalis preferred plants induced for 72 h. These preferences matched the dynamic changes in HIPV blends over time. Gene expression analysis suggested that the induced response after Spodoptera feeding is mainly controlled by the jasmonic acid pathway in both damaged and systemic leaves. Several genes involved in sulphide and green leaf volatile synthesis were clearly up‐regulated. This study thus shows that HIPV blends vary considerably over a short period of time, and these changes are actively regulated at the gene expression level. Moreover, temporal changes in HIPVs elicit differential preferences of herbivores and their natural enemies. We argue that the temporal dynamics of HIPVs may play a key role in shaping the response of insects associated with plants.     

Herbivore-induced plant volatiles mediate behavioral interactions between a leaf-chewing and a phloem-feeding herbivore

Plants respond adaptively to herbivore stress in order to maintain fitness. Upon herbivore attack, plants emit blends of volatile organic compounds (VOCs) that differ from those that are constitutively emitted. These defense responses are typically specific to the identity of the attacking herbivore and often linked to the herbivore's feeding guild (e.g. chewing, phloem-feeding). Herbivores use plant volatiles to locate suitable host plants and changes in volatile emissions can affect host-plant location. Therefore, herbivores from separate feeding guilds can interact indirectly through the modulation of plant responses. In this study we tested how damage by an herbivore from one feeding guild affected the host-plant choice of an herbivore from a separate feeding guild, and vice versa. A chewing herbivore, the Colorado potato beetle (Leptinotarsa decemlineata), and a phloem feeding herbivore, the green peach aphid (Myzus persicae), were assayed in olfactometers to assess behavioral responses to odors emitted by potato plants (Solanum tuberosum) that were damaged by herbivores from the other feeding guild. Leptinotarsa decemlineata oriented more frequently towards undamaged plants compared to M. persicae damaged plants. Surprisingly, M. persicae preferred plants that were damaged by L. decemlineata, although previous studies had shown that they perform worse on these plants. Distinct differences were detected in the volatile profiles of herbivore-damaged and undamaged plants. Leptinotarsa decemlineata induced stronger volatile emissions compared to undamaged control plants, while M. persicae tended to suppress volatile emissions. These herbivores demonstrate contrasting induction of plant volatiles and behavioral responses. Exploring the nature of co-occurring herbivores and how they perceive potential hosts can play a significant role in understanding the ecological functions and community dynamics of plant plasticity and interactions with a variety of herbivores.     

Attraction of pepper weevil to volatiles from damaged pepper plants

Pioneer herbivorous insects may find their host plants through a combination of visual and constitutive host‐plant volatile cues, but once a site has been colonized, feeding damage changes the quantity and quality of plant volatiles released, potentially altering the behavior of conspecifics who detect them. Previous work on the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae), demonstrated that this insect can detect and orient to constitutive host plant volatiles released from pepper [Capsicum annuum L. (Solanaceae)]. Here we investigated the response of the weevil to whole plants and headspace collections of plants damaged by conspecifics. Mated weevils preferred damaged flowering as well as damaged fruiting plants over undamaged plants in a Y‐tube olfactometer. They also preferred volatiles from flowering and fruiting plants with actively feeding weevils over plants with old feeding damage. Both sexes preferred volatiles from fruiting plants with actively feeding weevils over flowering plants with actively feeding weevils. Females preferred plants with 48 h of prior feeding damage over plants subjected to weevil feeding for only 1 h, whereas males showed no preference. When attraction to male‐ and female‐inflicted feeding damage was compared in the Y‐tube, males and females showed no significant preference. Wind tunnel plant assays and four‐choice olfactometer assays using headspace volatiles confirmed the attraction of weevils to active feeding damage on fruiting plants. In a final four‐choice olfactometer assay using headspace collections, we tested the attraction of mated males and virgin and mated females to male and female feeding damage. In these headspace volatile assays, mated females again showed no preference for male feeding; however, virgin females and males preferred the headspace volatiles of plants fed on by males, which contained the male aggregation pheromone in addition to plant volatiles. The potential for using plant volatile lures to improve pepper weevil monitoring and management is discussed.     

Feeding and oviposition preference of Frankliniella occidentalis for crops and weeds in Kenyan French bean fields

Western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important pest of French beans in Kenya. However, information on the feeding activity and oviposition preference of WFT on crop and weed hosts associated with French beans in Kenya and other parts of the world is lacking. To determine the feeding and oviposition preference of WFT for crop and weed plants commonly encountered in French bean fields in Kenya, no‐choice and choice experiments were conducted using four important crop and weed plants. Among the crop plants tested, highest feeding and oviposition activity of WFT was recorded on courgette/zucchini (Cucurbita pepo L.) and French beans (Phaseolus vulgaris L.). Spinach beet (Beta vulgaris L.) and sweet pepper (Capsicum annuum L.) were of relatively minor importance for feeding and oviposition. Among the weeds tested, gallant soldier (Galinsoga parviflora Cav.) was the most preferred host plant for feeding and oviposition compared with Chinese lantern (Nicandra physaloides L.), wild crucifer (Erucastrum arabicum Fisch. & C.A. Mey.) and pigweed (Amaranthus hybridus L.). Phaseolus vulgaris was the most preferred host for feeding and oviposition in the presence of G. parviflora, E. arabicum and A. hybridus. A positive correlation between the number of feeding punctures and the number of eggs oviposited by WFT on crop and weed plants was observed. The results of this study show that P. vulgaris, C. pepo and G. parviflora are both relatively good feeding and oviposition hosts of WFT. Cucurbita pepo and G. parviflora may serve as potential sources of WFT outbreaks within French bean fields.     

乡土水生植物对富营养化水体的净化效果研究

为了解乡土水生植物净化富营养化水体的效果,研究了广东地区5种乡土水生植物对2种富营养化水体总氮(TN)、总磷(TP)的净化效果和植物的生长状况。结果表明,与无植物空白相比,5种乡土植物使低、高浓度水体的TN去除率分别提高了3.8%～13.3%和13.2%～17.1%,TP去除率分别提高了15.2%～22.1%和11.3%～57.6%,其中野荸荠(Eleocharis plantagineiformis)适用于净化低氮水体;酸模叶蓼(Polygonumlapathifolium)适用于高氮水体;三白草(Saururuschinensis)适用于低磷水体;菱角(Trapa komarovii)适用于低氮或高磷水体;水龙(Ludwigia adscendens)对2种水体均有较好的净化效果,对高磷水体效果极佳。5种乡土植物在低、高浓度水体中均旺盛生长,水龙的生物量净增长率分别达375.5%和539.8%,表现最优,其次为菱角;水葫芦(Eichhorniacrassipes)则在高浓度水体中腐烂死亡,加重了水体污染。水龙、菱角对污染物的吸收作用较强,对P的吸收能力显著优于其他植物(P0.05)。因此,5种乡土植物均可作为广东地区富营养化水体修复的备选植物,其中水龙和菱角的开发潜力最大。     

Volatile Exchange between Undamaged Plants - a New Mechanism Affecting Insect Orientation in Intercropping

Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants. However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not been explored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insect interaction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed to volatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimicking exposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potato volatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in the field reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of the phenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but also information on the emitter plants themselves. In this way responding plants could obtain information on whether the neighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as a response in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in the responding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants are potentially under constant exposure to these volatiles, our study has major implications for the understanding of how mechanisms within plant communities affect insects. This knowledge could be used to improve plant protection and increase scientific understanding of communication between plants and its impact on other organisms.     

Hylobius abietis L. feeding on the novel host Pinus brutia Ten. increases emission of volatile organic compounds

Plants respond to feeding by herbivorous insects by producing volatile organic chemicals, which mediate interactions between herbivores and plants. Yet, few studies investigated whether such plant responses to herbivory differ between historical host and novel plants. Here, we investigated whether herbivory by the pine weevil Hylobius abietis causes a release of volatile organic chemicals from a novel tree Pinus brutia and compared the relative amounts of volatiles released from herbivore's historical hosts and P. brutia. We collected volatiles emitted from P. brutia seedlings that were either subjected to feeding by H. abietis or no feeding. Our results indicated that feeding increased emission of volatile compounds, composed of monoterpenes and sesquiterpenes, and that the emission was several fold higher in the damaged seedlings than in undamaged seedlings. In particular, emission of monoterpenes and sesquiterpenes increased by 4.4‐and 10‐fold in the damaged plants, respectively. Strikingly, individual monoterpenes and sesquiterpenes showed much greater dissimilarity between damaged and undamaged seedlings. Furthermore, several minor monoterpenes showed negative relationships with the weevil gnawed area. We discussed these results with the results of previous studies focused on historical host plants of H. abietis and hypothesized the ecological relevance and importance of our results pertaining relevance to the plant–herbivory interactions.     

Effects of single and multiple herbivory by host and non‐host caterpillars on the attractiveness of herbivore‐induced volatiles of sugarcane to the generalist parasitoid Cotesia flavipes

It is well known that parasitoids are attracted to volatiles emitted by host‐damaged plants; however, this tritrophic interaction may change if plants are attacked by more than one herbivore species. The larval parasitoid Cotesia flavipesCameron (Hymenoptera: Braconidae) has been used intensively in Brazil to control the sugarcane borer, Diatraea saccharalisFabricius (Lepidoptera: Pyralidae) in sugarcane crops, where Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), a non‐stemborer lepidopteran, is also a pest. Here, we investigated the ability of C. flavipes to discriminate between an unsuitable host (S. frugiperda) and a suitable host (D. saccharalis) based on herbivore‐induced plant volatiles (HIPVs) emitted by sugarcane, and whether multiple herbivory (D. saccharalis feeding on stalk + S. frugiperda feeding on leaves) in sugarcane affected the attractiveness of HIPVs to C. flavipes. Olfactometer assays indicated that volatiles of host and non‐host‐damaged plants were attractive to C. flavipes. Even though host‐ and non‐host‐damaged plants emitted considerably different volatile blends, neither naïve nor experienced wasps discriminated suitable and unsuitable hosts by means of HIPVs emitted by sugarcane. With regard to multiple herbivory, wasps innately preferred the odor blend emitted by sugarcane upon non‐host + host herbivory over host‐only damaged plants. Multiple herbivory caused a suppression of some volatiles relative to non‐host‐damaged sugarcane that may have resulted from the unaltered levels of jasmonic acid in host‐damaged plants, or from reduced palatability of host‐damaged plants to S. frugiperda. In conclusion, our study showed that C. flavipes responds to a wide range of plant volatile blends, and does not discriminate host from non‐host and non‐stemborer caterpillars based on HIPVs emitted from sugarcane. Moreover, we showed that multiple herbivory by the sugarcane borer and fall armyworm increases the attractiveness of sugarcane plants to the parasitoids.     

The attractiveness of odorous esterified fatty acids to the potential biocontrol agent,Altica cyanea

The fatty acid composition of foliar buds, young, mature, and senescent leaves, and stem parts of the rice-field weed, Ludwigia adscendens L. (Onagraceae) was analyzed by thin layer chromatography and gas chromatography flame ionization detection. The analysis of fatty acid composition revealed that saturated fatty acids (i.e., C14:0, C16:0, and C18:0) were prevailing compounds among the all weed parts except senescent leaves where C18:1 was predominant. The esterified fatty acids isolated from different weed parts over the range of 10–100 μg/ml followed by individual synthetic esterified fatty acids that were identified from the esterified extracts of different weed parts, and a mixture of synthetic esterified fatty acids except esterified eicosenoic acid and docosahexaenoic acid were applied to identify their role as a chemical cue for a potential biocontrol agent, Altica cyanea (Weber) (Coleoptera: Chrysomelidae) in a Y-tube olfactometer under laboratory conditions. In this bioassay, the esterified fatty acids from mature leaves and stem parts of this weed attracted A. cyanea at 20–100 μg/ml and at 80 μg/ml concentrations, respectively. Clear attraction was recorded by female A. cyanea insects in the mixture of synthetic esterified fatty acids at 60, 80, and 100 μg/ml concentrations. It is thus concluded that A. cyanea rely on an effective proportion of esterified fatty acids as an olfactory cue for attraction.     

Interaction of Anthonomus grandis and cotton genotypes: biological and behavioral responses

The boll weevil, Anthonomus grandisBoheman (Coleoptera: Curculionidae), is a key pest of cotton, Gossypium hirsutumL. (Malvaceae). Knowledge about boll weevil feeding and oviposition behavior and its response to plant volatiles can underpin our understanding of host plant resistance, and contribute to improved monitoring and mass capture of this pest. Boll weevil oviposition preference and immature development in four cotton genotypes (CNPA TB90, TB85, TB15, and BRS Rubi) were investigated in the laboratory and greenhouse. Volatile organic compounds (VOCs) produced by TB90 and Rubi genotypes were obtained from herbivore‐damaged and undamaged control plants at two phenological stages – vegetative (prior to squaring) and reproductive (during squaring) – and four collection times – 24, 48, 72, and 96 h following herbivore damage. The boll weevil exhibited similar feeding and oviposition behavior across the four tested cotton genotypes. The chemical profiles of herbivore‐damaged plants of both genotypes across the two phenological stages were qualitatively similar, but differed in the amount of volatiles produced. Boll weevil response to VOC extracts was studied using a Y‐tube olfactometer. The boll weevil exhibited similar feeding and oviposition behavior at the four tested cotton genotypes, although delayed development and production of smaller adults was found when fed TB85. The chemical profile of herbivore‐damaged plants of both genotypes at the two phenological stages and time periods (24–96 h) was similar qualitatively, with 30 identified compounds, but differed in the amount of volatiles produced. Additionally, boll weevil olfactory response was positive to herbivory‐induced volatiles. The results help to understand the interaction between A. grandis and cotton plants, and why it is difficult to obtain cotton genotypes possessing constitutive resistance to this pest.     

Response of the parasitoid Telenomus podisi to induced volatiles from soybean damaged by stink bug herbivory and oviposition

Abstract

Egg parasitoids have a short time frame in which their host eggs are suitable for parasitism, and in several systems these parasitoids respond to plant volatiles induced by oviposition on the plant (either in isolation or in combination with feeding damage) as a means of finding suitable hosts. It is known that the parasitoid of pentatomid eggs Telenomus podisi responds to damage done to soybeans by female Euschistus heros, its preferred host. In this study our aim was to determine the type of E. heros damage to soybean (herbivory, oviposition or a combination of both) necessary for attraction of T. podisi. In a Y-tube olfactometer the parasitoid has shown to respond to the undamaged plant over clean air and herbivory-damaged plants over undamaged plants. However, the parasitoids did not respond to the treatments where oviposition occurred, either in isolation or in combination with herbivory. Analysis of volatile blends revealed that herbivory plus oviposition damage to soybean induced a volatile blend different to those induced when herbivory or oviposition occurred separately. These results, along with other results from this system, suggest that T. podisi uses plant volatile cues associated with female E. heros damage in order to be present when E. heros lays its eggs, and thus ensure its resource is optimal for parasitism.     

Response of the pollen beetle Meligethes aeneus to volatiles emitted by intact plants and conspecifics

The response of the pollen beetle Meligethes aeneus Fab. (Coleoptera, Nitidulidae) to the volatiles of undamaged plants and conspecifics was tested in a Y-tube-olfactometer-bioassay. Beetles that had hibernated preferred significantly the volatiles emitted by their most important host plant, oilseed-rape (Brassica napus L. ‘Lorar’) in the early bud-stage. However, the odour emitted by rye (Secale cereale L.), tomato plants (Solanum lycopersicum L.), and yarrow (Achillea millefolium L.) were also attractive when tested against the corresponding growing-medium. Dock plants (Rumex obtusifolius L.) and touch-me-not (Impatiens parviflora L.) possessed no attractive properties. When tested against each other, oilseed-rape was preferred significantly by M. aeneus above all other plants, with the exception of tomato. The results indicate that M. aeneus is able to locate its host plant by olfactory stimuli in the early bud-stage, i.e. in that stage in which the infestation begins in the field and when the typical yellow colour and floral scent of oilseed-rape are absent. Female pollen beetles avoided significantly the volatiles emitted by female conspecifics and an ether extract of conspecifics of mixed sex, while volatiles from males had no significant effect on females. Furthermore, males showed no preferences when responding to conspecific odour in the olfactometer. These results suggest the existence of an epideictic pheromone for M. aeneus.     

Response of Neoseiulus fallacis Garmen and Galendromus occidentalis Nesbitt (Acari: Phytoseiidae) to Tetranychus urticae Koch (Acari: Tetranychidae)-Damaged Hop Humulus lupulus (L.) (Urticales: Cannabaceae)

Abstract 1 The response of Neoseiulus fallacis Garmen and Galendromus occidentalis (Acari: Phytoseiidae) to Tetranychus urticae Koch (Acari: Tetranychidae)‐damaged and undamaged hop, Humulus lupulus (L.), plants was tested using a Y‐tube olfactometer. 2 Neoseiulus fallacis but not G. occidentalis was attracted to volatiles from T. urticae‐damaged hop plants when paired with undamaged plants. 3 The response of N. fallacis to these volatiles was stronger for plants severed at the soil surface than for intact plants. 4 There was no difference in the response of N. fallacis to severed or intact hop plants that had no spider mite damage, indicating that artificial wounding by severing alone does not elicit the production of attractive volatiles detectable to N. fallacis. These results are consistent with the existence of cross‐talk between signalling pathways initiated by feeding damage and artificial wounding that result in elevated levels of predator‐attracting volatiles.     

Internal transport of alien and native plants by geese and ducks: an experimental study

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Electrophysiological response to herbivore-induced host plant volatiles in the moth Spodoptera littoralis

In cotton, Gossypium hirsutum (Malvacae), the volatiles emitted from the plant change in response to herbivory. Ovipositing females of the Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) can discriminate between cotton plants subjected to larval feeding and undamaged plants during oviposition. In this study we investigate whether females of this moth can detect the herbivore-induced cotton volatiles. The response of female S. littoralis antennae to volatiles collected from cotton plants subjected to larval feeding was studied using GC-EAD (coupled gas chromatography electroantennographic-detection). By GC-EAD, responses to over 10 different cotton volatiles were observed. Using single sensillum technique the responses of short sensilla trichodea on the antennae of S. littoralis females to 19 cotton volatiles and 12 general plant volatiles were investigated. Responses to these volatiles were recorded from 108 receptor neurones. Several neurones activated by herbivore-induced cotton volatiles were recorded. For example, a neurone type responding to two homoterpenes [(E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene and (E)-4,8-dimethyl-1,3,7-nonatriene] and (E,E)-α-farnesene was frequently found. We also observed sensitive neurones responding specifically to the herbivore-induced volatiles (+/–)-linalool and indole. In general, a stimulus load of less than 1 ng was needed to activate these neurones. In addition, specific neurones were found for constitutive cotton volatiles released in connection with damage to the plant. An abundant neurone type responded to β-caryophyllene and α-humulene. Another neurone type responded specifically to the non-induced cotton volatile (Z)-jasmone. These results show that females of S. littoralis have receptor neurones that would make it possible to discriminate between damaged and undamaged plants using volatile signals.     

Herbivore-induced Blueberry Volatiles and Intra-plant Signaling

Herbivore-induced plant volatiles (HIPVs) are commonly emitted from plants after herbivore attack^1,2. These HIPVs are mainly regulated by the defensive plant hormone jasmonic acid (JA) and its volatile derivative methyl jasmonate (MeJA)^3,4,5. Over the past 3 decades researchers have documented that HIPVs can repel or attract herbivores, attract the natural enemies of herbivores, and in some cases they can induce or prime plant defenses prior to herbivore attack. In a recent paper⁶, I reported that feeding by gypsy moth caterpillars, exogenous MeJA application, and mechanical damage induce the emissions of volatiles from blueberry plants, albeit differently. In addition, blueberry branches respond to HIPVs emitted from neighboring branches of the same plant by increasing the levels of JA and resistance to herbivores (i.e., direct plant defenses), and by priming volatile emissions (i.e., indirect plant defenses). Similar findings have been reported recently for sagebrush⁷, poplar⁸, and lima beans⁹..Here, I describe a push-pull method for collecting blueberry volatiles induced by herbivore (gypsy moth) feeding, exogenous MeJA application, and mechanical damage. The volatile collection unit consists of a 4 L volatile collection chamber, a 2-piece guillotine, an air delivery system that purifies incoming air, and a vacuum system connected to a trap filled with Super-Q adsorbent to collect volatiles^5,6,10. Volatiles collected in Super-Q traps are eluted with dichloromethane and then separated and quantified using Gas Chromatography (GC). This volatile collection method was used n my study⁶ to investigate the volatile response of undamaged branches to exposure to volatiles from herbivore-damaged branches within blueberry plants. These methods are described here. Briefly, undamaged blueberry branches are exposed to HIPVs from neighboring branches within the same plant. Using the same techniques described above, volatiles emitted from branches after exposure to HIPVs are collected and analyzed.     

Nucleopolyhedrovirus infection enhances plant defences by increasing plant volatile diversity

Plant–herbivore–entomopathogen tri-trophic interactions and biodiversity are relatively understudied topics in ecology. Particularly, the effects of entomopathogens on herbivore-induced plant volatiles and plant volatile diversity on the defensive function of plants have not been studied in detail. We used soybean (Glycine max), beet armyworm larvae (Spodoptera exigua), and nucleopolyhedrovirus (NPV) as a tri-trophic system to determine whether NPV infection can promote the emission and diversity of volatiles from plants. We also investigated whether NPV infection affects the attraction of Microplitis pallidipes, an important endoparasitoid of larval S. exigua. Uninfested soybean plants released 7 detectable volatile compounds while plants fed upon by healthy and NPV-infected S. exigua larvae released 12 and 15 volatiles, respectively. Female parasitoids were more attracted to the volatiles from plants that were fed upon by NPV-infected larvae than healthy larvae, and more attracted to the volatiles from plants that were fed upon by healthy larvae than no larvae. The selective responses of parasitoids to plant odours increased as plant volatile diversity increased. Our study suggests that the NPV infection facilitates the release of plant volatiles and enhances the defensive function of plants by increasing plant volatile diversity which in turn attracts more parasitoids. Also, this work reveals that plants might accrue two indirect benefits from NPV infection, cessation of herbivore feeding and more parasitisation.     

The social wasp Polybia fastidiosuscula Saussure (Hymenoptera: Vespidae) uses herbivore‐induced maize plant volatiles to locate its prey

Social wasps in the Polybia genus are important for use as pest‐control agents in agricultural systems. The objective of this study was to investigate the behavioural responses of Polybia fastidiosuscula Saussure (Hymenoptera: Vespidae) to volatiles from maize, both constitutive volatiles and those induced by the herbivory of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae). To assess the behavioural response of P. fastidiosuscula to S. frugiperda larvae, undamaged plants, S. frugiperda‐damaged plants, mechanically damaged plants, mechanically damaged plants plus regurgitant from larvae and extracts from various treatments, bioassays were conducted in a Y‐olfactometer. In addition, the volatiles from plants subjected to different treatments were collected via aeration, and they were quantified and identified. The wasps showed a greater preference for plants with damage induced either by larval feeding or by being mechanically damaged plus regurgitant than for undamaged plants or either larvae alone or mechanically damaged plants. Wasps were more attracted to extracts from plants + S. frugiperda larvae and to an extract from mechanically damaged plants + the regurgitant of larvae compared to hexane. The primary compounds induced by herbivory for 5–6 h after the beginning of the damage or regurgitant treatment were identified as α‐pinene, β‐myrcene, (Z)‐3‐hexenyl acetate, limonene, (E)‐ocimene, linalool, DMNT, (E)‐β‐farnesene, TMTT and indole. The results presented here show that the social wasp P. fastidiosuscula uses herbivore‐induced plant volatiles from maize to locate its prey.