Entomologia Experimentalis et Applicata最新文献

Guidelines for conducting, analyzing, and interpreting electrical penetration graph (EPG) experiments on herbivorous piercing-sucking insects – G. P. Walker, A. Fereres & W. F. Tjallingii (https://doi.org/10.1111/eea.13434).

The sweet potato whitefly, Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae), is highly harmful to solanaceous crops. The use of essential oils (EOs) is promising for the management of several insect pests, promoting both lethal and sublethal effects. This study aimed to evaluate the effects of sublethal concentrations of Pelargonium graveolens L'Her (Geraniaceae) EO on the feeding behavior of B. tabaci MED on tomato plants (Solanum lycopersicum L., Solanaceae). For this research, the electrical penetration graph (EPG) technique was used to monitor whitefly stylet activities on their host plants. Two sets of plants were previously sprayed with two concentrations of EO (the LC₂₅ and LC₅₀, which were determined in a mortality test), a third set was treated with the insecticide cyantraniliprole, and a fourth set received a control treatment. Our results indicate that the insecticide cyantraniliprole and the EO could both reduce the stylet feeding activity of B. tabaci MED, as well as reduce the number and duration of phloem sap ingestion events (waveform E2), which could avoid or reduce the transmission of viruses. Thus, the application of sublethal concentrations of P. graveolens EO, as well as exposure to cyantraniliprole, negatively affected the feeding behavior of B. tabaci MED. This information may contribute to the management of this pest and the reduction of the incidence of viruses in tomato production.

Vibrational communication in the Auchenorrhyncha is an avenue of growing interest, with many pesticide-free vibrational pest control programmes against auchenorrhynchan agricultural pests continuing to be developed around the world. Passion vine hoppers (PVH), Scolypopa australis (Walker) (Hemiptera: Ricaniidae), are an economically damaging pest species in New Zealand, where they facilitate the growth of sooty mould in kiwifruit orchards. Scolypopa australis is already known to use vibrational signals, therefore a further understanding of the spectral and temporal characteristics of its calls will be an essential next step to developing vibration-based pest management strategies. Here, we aimed to characterise the properties of spontaneous S. australis calls in solitary and intrasexual communication contexts. We used laser Doppler vibrometry to record vibrational signals produced by male and female S. australis (separately), when in groups of three or individually. We sorted calls and call sub-units (syllables) into groups based on cluster analyses of various spatio-temporal parameters. We define four male calls and three female calls, and newly describe a ‘two-syllable’ calling structure that may be involved in male intrasexual competition. Certain syllables were more prevalent at the beginning or end of calls for males, and were more homogenously distributed throughout calls for females. The types of calls used differed between single males and groups, with more energetically intense call types observed in the group settings. Additional studies on the behavioural context of S. australis vibrational calls and their responses to playback of such calls will be necessary to assess the viability of vibration-based pest management for this species.

The African fig fly, Zaprionus indianus Gupta (Diptera: Drosophilidae), is an ecologically diverse pest species that interacts with and feeds on various microbial pathogens including bacteria and yeast found in decomposing fruits. However, the interaction of Z. indianus with its microbial community and microbial pathogens is obscure. To determine the presence of fungal pathogens, we collected wild Z. indianus from the northwestern part of the Indian subcontinent. Based on molecular identification and phylogenetic analysis, Debaryomyces hansenii (Zopf) Lodder & Kreger-van Rij (isolate ziha1) was the most commonly observed fungus associated with Z. indianus. Furthermore, we identified two more opportunistic fungal pathogens: Aspergillus flavus Link (isolate zias2), and Pichia kudriavzevii Boidin, Pignal & Besson (isolate zibd3). The interaction of isolated fungi with Z. indianus was evaluated in terms of larval mortality, adult emergence, and fecundity. Debaryomyces hansenii ziha1 resulted in 90% emergence rate for adults, and did not cause significant mortality in the larval stage. In contrast, A. flavus zias2 and P. kudriavzevii zibd3 showed a significant reduction in fecundity and caused 99% and 74% larval mortality of Z. indianus, respectively. In the laboratory oviposition preference assay, mated females of Z. indianus preferred D. hansenii ziha1 supplemented food with a positive oviposition index compared to the uninfected control and compared to food infected with P. kudriavzevii zibd3 or A. flavus zias2. These findings underscore Z. indianus' potential to act as a reservoir for both symbiotic and pathogenic fungal species, some of which may be further harnessed for effective fruit fly pest control strategies.

Among phytophagous insects, life history often evolves as a strategy to cope with seasonality in host plant availability. Whereas specialization often leads to dormancy, aestivation, or longevity, polyphagous species bridge between periods of host availability by exploiting alternative host plants. The aim of the present work was to characterize the life histories of four species of specialist and generalist uni- and multivoltine frugivorous fruit flies – Ceratitis capitata Wiedemann, Anastrepha fraterculus Wiedemann, Rhagoletis blanchardi Aczel, and Rhagoletotrypeta pastranai Aczel (all Diptera: Tephritidae) – inhabiting in sympatry in Las Yungas phytogeographical province in Tucumán (northwestern Argentina). For this purpose, infested host plant fruits were sequentially collected during two consecutive years, and flies recovered from these fruits were subjected to demographic experiments to establish longevity and overwintering mechanisms. The results indicated that life cycles were tightly related to host fruit availability, where multivoltine species sequentially exploit different host plants over the year, whereas univoltine species must undergo pupal dormancy to reach the next host fructification period and may extend the duration of dormancy when climatic conditions are acyclic and unpredictable. The present study may broaden knowledge about diapausing Tephritidae in subtropical regions and may contribute to an increased conceptual basis for the improvement of pest control strategies, such as the sterile insect technique (SIT).

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive insect pest that has caused significant economic losses in a myriad of agricultural crops in Europe and the USA. The communication as well as the control of this pest largely rely on semiochemicals (e.g., pheromones) and semiophysicals (e.g., substrate-borne vibrations). Nevertheless, the nocturnal activity of H. halys is still largely unknown. In the present study, the diel vibrational communication of H. halys was investigated in controlled laboratory and semi-field conditions. Moreover, the relevance of this ecological trait for integrated pest management (IPM) strategies was assessed by extending playback periods of bimodal (i.e., pheromones + vibrational playbacks) traps to 24 h, and comparing it to the current trap model (solar panel, about 12 h of playback) and a control (no playback, only pheromone). We found that H. halys did not exhibit discernible differences of vibrational activity between photophase and scotophase, with the exception of signal type 2 that in laboratory conditions was predominately emitted within nocturnal and morning hours (i.e., 20:00–12:00). Additionally, the calling activity was negatively affected by warmer (>32 °C) and windier (>7 m s⁻¹) conditions in semi-field settings. Bimodal traps that were power-supplied for 24 h captured significantly more males than the other groups, and more females than the control group. Results suggest that the nocturnal vibrational activity of H. halys should be accounted for within IPM strategies by activating the bimodal traps also during the scotophase.

Morphological plasticity may be induced by altering host plants and commonly it is sex-specific in phytophagous insects. It is hypothesized that stress in insects caused by a host shift leads to morphological changes and developmental destabilization, which may be identified by fluctuating asymmetry. We performed reciprocal transplant experiments in eight replicated populations of the seed beetle Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae, Bruchinae) adapted to common bean (Phaseolus vulgaris L., Fabaceae) as its ancestral host and chickpea (Cicer arietinum L., Fabaceae) as a suboptimal host. Using methods of geometric morphometrics we assessed the effects of the short- and long-term host shift on size and shape variation of beetles of both sexes. We also tested the hypothesis that fluctuating asymmetry is lower when the beetles develop within seeds of the ancestral host. Our results showed that females respond more plastically related to their body size and shape of the abdomen, particularly during a short-term host shift, suggesting that females have a greater importance in maintaining the population on a new host. The level of fluctuating asymmetry is lowest in males that have evolved for generations on bean indicating that they have the most canalized development, so we suggested that symmetry in A. obtectus is maintained by sexual selection. Even if the beetles are adapted to a suboptimal host over many generations, they stabilize their development after returning to the ancestral host. Our work indicates that host shifts may change morphological aspects of the beetles in a sex-specific manner and consequently influence their developmental trajectories.

Natural vegetation in and around crops effectively increases predators. Semi-natural habitats (SNHs; non-crop vegetation) surrounding crops provide refuge and resources. However, the function of SNHs may depend on several factors, and the response of natural predators may vary among crops and regions. Here, we examined the spider community in a SNH and at an adjacent vineyard in a semi-arid region of Argentina. We collected spiders in a gradient from an adjacent SNH, towards the vineyard at three distances from the SNH using two techniques: beating and pit-fall traps. We collected spiders in December and February during two consecutive years at two strata: in vegetation and on the ground. In vegetation, spider abundance significantly decreased from SNH towards the interior of the vineyard at 80 m. On the ground, spider abundance was also significantly higher in SNH. However, after decreasing at the 5 and 20 m sites inside the vineyard, the abundance increased at 80 m. For foliage spiders, species richness followed the same pattern as abundance, whereas ground spider richness significantly increased from SNH to the interior of the vineyard. Species composition also showed different tendencies between foliage and ground spiders. The foliage spider community differed between SNH vs. all the vineyard sites. Contrarily, at the ground stratum, SNH was similar in composition to the edge of the vineyard, and they both differed from the other vineyard sites. We found that the adjacent SNH influenced the spider community in the vineyard and that this effect depended on the distance from that habitat and the association of the community to various strata. These results highlight the importance of studying the whole community of spiders when aiming to increase predator abundance to enhance biological control in this kind of crop. In addition, we found species that may act as indicators of native vegetation which has important implications for the management of natural habitats in this region.

Grape berry moths, particularly Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae), and vinegar flies, such as Drosophila melanogaster Meigen and Drosophila suzukii Matsumura (Diptera: Drosophilidae), are important vineyard pests, causing severe quality loss of grapes. Several arthropod taxa may be involved in the natural control of these pests. However, the role of arthropod predators in the natural control of vineyard pests remains unclear. We investigated 32 vineyards in the Palatinate region, southwest Germany, under organic and conventional management, which in both cases received either full or reduced fungicide applications (2 × 2 design). Predation of L. botrana eggs and pupae and D. melanogaster pupae on sentinel cards exposed in the vineyards was observed with infrared cameras. In total, nine predator taxa could be identified. The most dominant predator was the European earwig, Forficula auricularia L. (Dermaptera: Forficulidae), with 90% of all predation events. We conclude that F. auricularia is likely a key predator of vineyard pests, and that special attention should be paid to maintain it at high population densities.

The invasive alien stink bug Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae), native to eastern-southern Africa and central-southern Asia, poses significant economic threats to agroecosystems due to its polyphagous diet with a preference for brassicaceous crops. Current control methods using broad-spectrum insecticides are expensive and often result in significant negative ecological impacts, as well as posing a health risk to consumers. This study provides a detailed description of the mating behavior of B. hilaris, with the aim to ascertain whether substrate-borne vibrations have a role in premating phases. Such knowledge may contribute to the development of alternative biorational control techniques employing vibrational strategies. Virgin adults were tested individually or in pairs on different substrates, that is, a loudspeaker membrane and a bean plant. Vibrations emitted by males and females were recorded using a laser Doppler vibrometer, and the following spectral and temporal parameters were analyzed: fundamental frequency, emission time, repetition time, and signal modulation. Three distinct types of vibration emitted by males and females were identified: a male vibrotype (MV-1), a female vibrotype (FV), and a copula signal exclusively emitted by males (MS-2). MV-1 and FV were emitted prior to genitalia contact, whereas MS-2 was emitted within the mounting and engagement phases. Statistical analysis revealed significant transitions in behavioral phases for couples that achieved mating. By analyzing the walking behavior, there was an inverse relationship between motility and signal emission when comparing the two sexes, which suggests that males might engage in a form of searching behavior. These findings provide insight into the crucial role of vibrational communication to achieve mating in B. hilaris.