Field superparasitism by Phymastichus coffea, a parasitoid of adult coffee berry borer, Hypothenemus hampei

Superparasitism by Phymastichus coffea LaSalle (Hymenoptera: Eulophidae), a parasitoid of adults of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), was recorded under field conditions in a coffee plantation in Colombia. Parasitoid adults were released 1, 5, and 9 days after artificial infestations of 90‐, 150‐, and 210‐day‐old coffee berries with H. hampei females. The position of the beetle inside the berry and the number of P. coffea larvae per female host were assessed 10 days after each parasitoid release. Under laboratory conditions, P. coffea usually lays two eggs per host, one female and one male. In our studies, we often recorded more than six P. coffea larvae in an individual host and mean numbers of larvae per host ranged from two to 4.45. Superparasitism by P. coffea under field conditions was influenced by the age of the coffee berries, which is the most important factor determining the speed of penetration by H. hampei, and therefore the time the beetles are exposed to a P. coffea attack. The number of parasitoid larvae in each H. hampei female gradually decreased with the age of the berry, and also linearly decreased with the time of parasitoid release. Age‐dependent effects of coffee berries that alter the ratio of available hosts to searching parasitoids by providing refuges to the herbivore, largely determine the extent of superparasitism of H. hampei by P. coffea under fields conditions in Colombia.     

Development of an improved laboratory production technique for the coffee berry borer Hypothenemus hampei, using fresh coffee berries

The suitability of a mixture of plaster of Paris and charcoal as a means to regulate the moisture content of coffee berries and the relative humidity (moisture conditions) of the rearing environment and its impact on rearing the coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae), was evaluated under laboratory conditions using two types of coffee. Coffee berries were kept individually in vials with a 1-cm layer of the mixture, and the fresh weight of the berries was assessed, as well as the penetration of CBB into the berries, its survival, and its progeny production over a period of 55 days. Significantly higher survival and progeny production was achieved when using the mixture regardless of the coffee type. Compared to the vials without plaster of Paris/charcoal, a six- to sevenfold increase in survivorship of the F1 was recorded when using plaster of Paris/charcoal and in the latter treatment berries harboured on average more than 100 individuals, whereas only 1.7 in the vials without plaster of Paris.     

Optimization of coffee berry borer, Hypothenemus hampei Ferrari (Col., Scolytidae), mass trapping with an attractant mixture

Mass trapping is a technique currently being considered to control the coffee berry borer (CBB), Hypothenemus hampei Ferrari (Col., Scolytidae), as part of the integrated management of its populations. However, the research undertaken in this field has variable and sometimes contradictory results. The purpose of this study carried out with a single type of trap (experimental model '1B') was to evaluate the technique and define parameters for its efficient use. The first result obtained was detection of the excellent attractant properties of the ethanol–methanol mixture, and its efficiency related to the proportion of the two alcohols. Coffee borers were not attracted to traps with caffeine, green coffee powder, freshly pulped and hulled coffee berries and ground CBB. It was shown that the ethanol–methanol mixture (1 : 1) release rate varied without affecting the capture rate, and that the red colour of the trap substantially increased CBB attraction. In terms of trap set-up, it was found that capture rates were three times better with a trap height at 1.2 m, than that for a position near ground level. In addition, the best density of traps for achieving efficient mass trapping was 22 units per hectare. These results show the importance of developing an attractant using pure compounds, and of improving the trap and the trapping technique in line with CBB behaviour.     

Phylogenetic origins of African and Neotropical Beauveria bassiana s.l. pathogens of the coffee berry borer, Hypothenemus hampei

A phylogenetic epidemiological study of Beauveria bassiana s.l. was conducted for African and Neotropical pathogens of the coffee berry borer (CBB), Hypothenemus hampei, based on inferences from two nuclear intergenic regions, EFutr and Bloc. CBB pathogens were distributed among four terminal clades, however, the majority of African and Neotropical isolates cluster in a well-supported monophyletic group, informally designated AFNEO_1. Although the relationship between African and Neotropical AFNEO_1 is unresolved, the majority of alleles detected were exclusive to either the African or the Neotropical populations. These fixed genetic differences suggest that their disjunction predates the world trade in coffee. Neotropical AFNEO_1 have a broad host range and CBB pathogens are intermixed phylogenetically with isolates from diverse indigenous insects. Several Neotropical AFNEO_1 isolates were isolated from coffee plants as epiphytes or endophytes, thus plants themselves may potentially serve as reservoirs of pathogens against their insect pests. Topological incongruence between the EFutr and Bloc phylogenies of Neotropical AFNEO_1 may signify that individuals within this population are recombining.     

Efficacy of plant essential oils against two major insect pests of coffee (Coffee berry borer,Hypothenemus hampei,and antestia bug,Antestiopsis intricata) and maize weevil,Sitophilus zeamais

Coffee berry borer, antestia bug and maize weevil are serious pest of coffee and maize, respectively. Bioassays of plant essential oils were conducted with coffee berry borer, antestia bug and the maize weevil. Essential oils of Thymus vulgaris, Aloysia sp., Ruta chalepensis, Chenopodium ambrosioides and Cymbopogon nardus resulted in 80%–90% mortality of coffee berry borer, whereas essential oils of C. ambrosioides, T. vulgaris and R. chalepensis achieved 87.5%–92.5% mortality of antestia bug. Essential oils of C. ambrosioides caused significantly the highest percentage mortality of the maize weevils (95%) with “Lethal Dose” (LD₅₀) values of 2.202 ml 100 ml^?1 within 24 h after treatment, whereas essential oils of Mentha spicata, T. vulgaris and R. chalepensis resulted in 82.5%, 77.5% and 73.5% mortality, respectively. The potential of plant essential oils for the management of coffee berry borer, antestia bug and maize weevil for the small-scale farmers is discussed.     

Sequences and transcriptional analysis of Coffea arabica var. Caturra and Coffea liberica plant responses to coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) attack

The coffee berry borer (CBB) is the most prevalent pest of coffee plantations. Within the Coffea genus, C. arabica is susceptible to CBB and C. liberica shows a lower susceptibility. Two EST libraries were constructed from the total RNA of C. arabica and C. liberica fruits artificially infested with CBBs for 24 h. Using 6000 clones sequenced per library, a unigene database was generated, obtaining 3634 singletons and 1454 contigs. For each contig, the proportion of sequences present in both species was determined and a differential gene expression between the species was detected. C. arabica displayed a higher relative expression of proteins involved in general stress responses, whereas C. liberica showed the induction of a higher number of insect defense proteins. In order to validate the results, quantifications through real-time PCR were done. A hevein-like protein, an isoprene synthase, a salicylic acid carboxyl methyltransferase and a patatin-like protein gene were highly upregulated in C. liberica at 24 and/or 48 h after insect infestation compared to C. arabica. The identification of metabolic pathways induced by this pest insect provides tools to take advantage of the genetic resources available for the control of CBB.     

塔克拉玛干沙漠腹地人工植被及土壤CNP的化学计量特征

生态化学计量学是研究生态过程和生态作用中化学元素平衡的科学。极端环境中进行植物叶片与土壤中营养元素含量及变化研究,对于揭示植物对营养元素的需要和当地土壤的养分供给能力,以及植物对环境的适应与反馈能力具有十分重要的意义。以塔克拉玛干沙漠腹地塔中植物园生长良好的25种人工植被及其生境为研究对象,运用方差分析、相关分析综合研究植物叶片及土壤的化学计量特征及其相互关系。结果显示:塔克拉玛干沙漠腹地25种人工植被叶片C、N、P的平均含量分别为(386.7±46.6)、(24.7±8.1)和(1.8±0.78) mg/g;叶片C:N、C:P及 N:P分别为(17.5±6.7)、(249.2±102.8)、(15.0±5.6)。其中豆科植物N含量极显著高于非豆科植物(P<0.001)。不同生活型植物的C、N、P含量均存在显著差异,C、N、P含量在3种生活型的大小顺序为草本>灌木>乔木。C:N和N:P在不同生活型植物间不存在显著差异(P>0.05),而乔木和灌木的C:P显著高于草本植物(P< 0.05)。相关分析表明植物的叶片C:N、C:P都与相应的N、P含量呈现极显著负相关性(P<0.001),而叶片N含量与P含量的变化并不相关(P> 0.05)。土壤C、N、P养分元素含量远低于全国的平均水平,尤其是N含量(<0.2 mg/g);土壤C与N存在着极显著的正相关关系(P<0.01),而C与P、N与P间的相关性并不显著(P>0.05)。以上研究结果表明,受极端环境的限制,塔克拉玛干沙漠人工植被植物对养分元素的利用效率显著低于全国陆地植物的平均水平,不同科和不同生活型功能群植物对环境的适应能力显著不同,表现出显著的养分适应策略差异性。     

Effects of defoliation on the resistance and tolerance of rice,Oryza sativa,to root injury by the rice water weevil,Lissorhoptrus oryzophilus

Understanding plant‐mediated interactions in agricultural systems may facilitate the development of novel and improved management practices, which is important, as management of these insects is currently heavily reliant on insecticides. The fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae, Prodeniini), is a sporadic pest of rice fields in the southern USA. In southwestern Louisiana, this defoliating insect typically attacks rice early in the growth season, before fields are flooded. Defoliation by fall armyworm larvae may trigger increased expression of plant defenses, which may result in increased resistance to subsequent herbivores. The rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae, Stenopelmini), enters rice fields as an adult both before and after flooding, but oviposition and larval infestation occur only after fields are flooded. RWW may be affected by changes in plant resistance caused by fall armyworm defoliation before flooding. The objectives of this study were to investigate the plant‐mediated effects of natural and artificial defoliation on population densities of RWW larvae after flooding and on the ability of rice plants to compensate for root injury by RWW larvae. In the 2015 season, fall armyworm defoliation before flooding resulted in reduced RWW densities after flooding. However, in 2016 no significant effects of fall armyworm defoliation on densities of RWW larvae were detected. Similarly, mechanical defoliation of rice before flooding did not affect RWW densities after flooding. Although lowest yields were observed in plots subjected to both root injury and defoliation, there was little evidence of a greater than additive reduction in yields from simultaneous injury. These results suggest a lack of plant‐mediated interactions among these two pests in rice in the southern USA.     

Progeny of the maize weevil,Sitophilus zeamais,is affected by parental exposure to clove and cinnamon essential oils

The interest in and utilization of botanical insecticides, particularly essential oils, has become increasingly relevant to the control of insect pests. However, the potential ecotoxicological risks or flaws (including sublethal effects on the targeted pest generation and its subsequent progeny) of this pest control tool have been neglected frequently. Here, we evaluated the effects of sublethal exposure to clove, Syzygium aromaticum (L.) Merrill & Perry (Myrtaceae), and cinnamon, Cinnamomum verum J. Presl (Lauraceae), essential oils on adult (F0) maize weevils, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and the physiology (e.g., body mass, respirometry, and grain consumption) and population dynamics (e.g., daily emergence and sex ratio) of their progeny. Longevities of the parents were negatively affected by the essential oils in a concentration‐dependent manner. Parental sublethal exposure to clove oil (0.17 μl cm^?2) accelerated offspring emergence but delayed the emergence of females compared to males. Parents that were sublethally exposed to clove (0.17 μl cm^?2) or cinnamon (0.35 μl cm^?2) essential oils produced heavier offspring. Parental sublethal exposure to cinnamon essential oil accelerated offspring emergence (at 0.70 μl cm^?2), delayed female emergence (at 0.17 μl cm^?2), and enhanced grain consumption (at 0.35 and 0.70 μl cm^?2) of the progeny. Thus, our findings indicate that sublethal exposure to clove and cinnamon essential oils is capable of promoting transgenerational effects in S. zeamais that can negatively impact the control efficacy of such products.     

Behavioural responses of the vine weevil, Otiorhynchus sulcatus, to semiochemicals from conspecifics, Otiorhynchus salicicola, and host plants

The vine weevil Otiorhynchus sulcatus is a parthenogenetic reproducing species which forages for suitable host plants at night, but is found congregated in dark places during the day. Frass of this weevil species is suspected to contain attractive compounds that are host‐plant related. Using a still‐air olfactometer, we tested adult vine weevils at night for their behavioural response to odours from conspecifics, feeding on a mixture of spindle tree (Euonymus fortunei) and yew (Taxus baccata), and to a sexually reproducing related species (Otiorhynchus salicicola), feeding on a mixture of ivy (Hedera helix) and cherry laurel (Prunus laurocerasus). Their attraction to conspecifics and O. salicicola appeared to be related to frass production. Freshly collected frass from O. sulcatus and from O. salicicola males and females was attractive. Prunus laurocerasus and H. helix have not been observed to be hosts of the vine weevil in the field. However, our tests showed that the vine weevil was attracted to mechanically damaged leaves of both plant species, whereas undamaged leaves were not attractive. Only undamaged young unfolding leaves of H. helix were also attractive. The attraction to odours from mechanically damaged host and non‐host plants suggested the involvement of compounds that are commonly found in many plant species. The involvement of plant compounds and/or aggregation pheromones in attraction to frass of the vine weevil and frass of the related weevil species O. salicicola is discussed.     

Variations in the Volatile Organic Compound Emission Potential of Plant Functional Groups in the Temperate Grassland Vegetation of Inner Mongolia, China

The biogenic volatile organic compounds (VOC) emitted by the vegetation of a terrestrial ecosystem play a key role in both regional air quality and tropospheric chemistry. To describe the general emission properties of VOC of different plant functional groups (PFG) in a typical temperate grassland in Inner Mongolia, China, we randomly selected 175 plant species and measured the quantities of isoprene and monoterpene in situ. Results showed that most plants had low VOC emission potential at the species level,especially for some dominant plants, such as Leymus chinensis Tzvel., Stipa grandis Smirn., and Agropyron cristatum Gaertn. At the PFG level, the lowest VOC emission potential was found for perennial rhizome grasses, a major PFG in a typical temperate grassland ecosystem. The effects of overgrazing and subsequent vegetation succession on the emission of VOC by different plant life form functional groups (PLFG)were also discussed.     

Variations in the Volatile Organic Compound Emission Potential of Plant Functional Groups in the Temperate Grassland Vegetation of Inner Mongolia, China

The biogenic volatile organic compounds (VOC) emitted by the vegetation of a terrestrial ecosystem play a key role in both regional air quality and tropospheric chemistry. To describe the general emission properties of VOC of different plant functional groups (PFG) in a typical temperate grassland in Inner Mongolia, China, we randomly selected 175 plant species and measured the quantities of isoprene and monoterpene in situ. Results showed that most plants had low VOC emission potential at the species level,especially for some dominant plants, such as Leymus chinensis Tzvel., Stipa grandis Smirn., and Agropyron cristatum Gaertn. At the PFG level, the lowest VOC emission potential was found for perennial rhizome grasses, a major PFG in a typical temperate grassland ecosystem. The effects of overgrazing and subsequent vegetation succession on the emission of VOC by different plant life form functional groups (PLFG)were also discussed.     

Separation of early and late responses to herbivory in Arabidopsis by changing plasmodesmal function

Herbivory results in an array of physiological changes in the host that are separable from the associated physical damage. We have made the surprising observation that an Arabidopsis line (pdko3) mutated in genes encoding plasmodesmal proteins is defective in some, but not all, of the typical plant responses to herbivory. We tested the responses of plasma transmembrane potential (Vm) depolarization, voltage gated K⁺ channel activity, cytosolic calcium [Ca²⁺]_cyt and reactive oxygen species (ROS) (H₂O₂ and NO) release, shoot‐to‐root signaling, biosynthesis of the phytohormone jasmonic acid (JA) and the elicitation of volatile organic compounds (VOCs). Following herbivory and the release of factors present in insect oral secretions (including a putative β‐galactofuranose polysaccharide), both the pdko3 and wild type (WT) plants showed a increased accumulation of [Ca²⁺]_cyt, NO and H₂O₂. In contrast, unlike WT plants, the mutant line showed an almost complete loss of voltage gated K⁺ channel activity and Vm depolarization, a loss of shoot‐induced root‐Vm depolarization, a loss of activation and regulation of gene expression of the JA defense pathway, and a much diminished release and altered profile of VOCs. The mutations in genes for plasmodesmal proteins have provided valuable genetic tools for the dissection of the complex spectrum of responses to herbivory and shown us that the responses to herbivory can be separated into a calcium‐activated oxidative response and a K⁺‐dependent Vm‐activated jasmonate response associated with the release of VOCs.     

Anatomy of the stridulation apparatus of the beech leaf‐mining weevil and characterization of,and behavioral responses to,stridulation sounds

We investigated auditory signals and morphology of the stridulatory apparatus of the European beech leaf‐mining weevil, Orchestes fagi L. (Coleoptera: Curculionidae), an invasive herbivore now established in Nova Scotia, Canada, to determine their potential for enhancing survey tools to monitor the spread of the species in Canada. We recorded and described sounds produced by adult O. fagi, analyzed the morphology of the stridulatory mechanism for intersexual differences and asymmetry, and examined behavioral responses elicited in conspecifics by playback of stridulation recordings. Adult O. fagi produced sounds under three conditions: male in distress, female in distress, and male in the presence of female. Female distress chirps lasted significantly longer than male distress chirps and male chirps in the presence of females, but peak frequencies and mean number of chirps per s did not differ significantly among the three groups. Morphology of the stridulation structures in male and female O. fagi was compared using scanning electron microscopy. Orchestes fagi have an elytro‐tergal file‐ and scraper‐type sound production apparatus, through which sound is produced upon anterior motion of the abdomen. Female O. fagi have a ‘pars stridens’ that is longer and has more ridges than males. Width and number of ridges per length of pars stridens did not differ between the sexes. Evidence of asymmetry was found in male pars stridens, with the right side being longer than the left. Playback of recorded sounds to adult weevils suggests female O. fagi were repelled by sounds produced by distressed males.     

Olfactory responses of Rhopalosiphum padi to three maize,potato, and wheat cultivars and the selection of prospective crop border plants

Understanding host plant volatile – aphid interactions can facilitate the selection of crop border plants as a strategy to reduce plant virus incidence in crops. Crop border plant species with attractive odours could be used to attract aphids into the border crop and away from the main crop. As different cultivars of the same crop can vary in their olfactory attractiveness to aphids, selecting an attractive cultivar as a border crop is important to increase aphid landing rates. This study evaluated olfactory responses of the bird cherry‐oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), to three cultivars each of maize [Zea mays L. (Poaceae)], potato [Solanum tuberosum L. (Solanaceae)], and wheat [Triticum aestivum L. (Poaceae)] with the aim of selecting an attractive crop border plant to reduce the incidence of the non‐persistent Potato virus Y [PVY (Potyviridae)] in seed potatoes. Volatiles emitted by the crop cultivars were collected and identified using coupled gas chromatography/mass spectrometry. Quantitative and qualitative differences were found among cultivars. Behavioural responses of alate R. padi to odours of the cultivars and synthetic compounds identified from the plants were determined with a four‐arm olfactometer. Rhopalosiphum padi was attracted to odours emitted from maize cultivar 6Q‐121, but did not respond to odours from the remaining eight crop cultivars. Volatile compounds from maize and wheat cultivars that elicited a behavioural response from R. padi and contributed to differences in plant volatile profiles included (Z)‐3‐hexenyl acetate (attractant) and α‐farnesene, (E)‐2‐hexenal, indole, and (3E,7E)‐4,8,12‐trimethyltrideca‐1,3,7,11‐tetraene (TMTT) (repellents). We conclude that maize cv. 6Q‐121 is potentially suitable as a crop border plant based on the behavioural response of R. padi to the olfactory cues emitted by this cultivar. The findings provide insight into selecting crop cultivars capable of attracting R. padi to crop border plants.