Early Starvation Contributes to the Adaptive Capacity of Corythucha marmorata (Uhler), an Emerging Pest in China

Food shortages severely reduce the prospects of insect survival in natural settings, including in the case of herbivorous insects. However, the early starvation experience of some insects has positive effects throughout their entire lifespan. It is important to discuss the effects of refeeding and host plants on the capacity of herbivorous insects to adapt to starvation and low temperatures, considering that starvation resistance is expected to show some degree of adaptive phenotypic plasticity. We tested the relationship between host plant, starvation, and the supercooling capacity of the invasive pest Corythucha marmorata. In particular, we highlighted how early starvation affects the refeeding and recovery phases. Among the various range of hosts, the chrysanthemum lace bug has the fastest growth rate on Helianthus annuus, and the strongest supercooling capacity on Symphyotrichum novi-belgii. Especially, starvation for 2 days increases the rates of survival, development, and number of eggs upon refeeding, in comparison to no starvation. A 3-day starvation period in the nymphal stage significantly increased the supercooling capacity of 5th instar nymphs and adults, as observed in our study.

Thraulodes Ulmer 1920 (Ephemeroptera: Leptophlebiidae) from Espírito Santo state, Brazil

Based on material collected during the past 10 years in the State of Espírito Santo and adjacent areas in Minas Gerais, Southeastern Brazil, we identified three species of the genus Thraulodes: T. itatiajanus Traver & Edmunds, for which we present new records and description of the female imago; T. luisae Souto, Da-Silva & Nessimian, first recorded for the state and for which we describe the nymphal stage; and T. alegre sp. nov., described based on male and female imago. The main diagnostic characteristics of the new species are: color of abdominal terga I–VI whitish translucent, terga II–VI with subrectangular dark brown mark near posterior margin and with midway spot; styliger plate triangular and whitish; penes light yellow, with lateral pouch and penes spines long and tapered, with robust bases.

Contribution to the knowledge of the genus Takobia Novikova & Kluge, 1987 (Ephemeroptera, Baetidae) in Central Asia

Based on the original type material, the nymphal stage of the mayfly Takobia maxillare is redescribed; in parallel, a lectotype is designated. Takobia maxillare is the type species of the genus Takobia, and an accurate and complete knowledge of its morphology is crucial to the delimitation of this problematic genus and clarification of its phylogenetic affinities. Ambiguous characters, previously reported for this species in the literature are clarified. Furthermore, two new species in the same genus are described, namely Takobia sinusopalpatasp. nov. and Takobia shughnonicasp. nov. based on the morphology of nymphs from Central Asia, supplemented with COI sequences. Implications for the systematics of Takobia and related taxa are discussed and the need for an extensive phylogenetic study of this group is stressed.

A new species of Neohagenulus Traver, 1938 from Hispaniola (Ephemeroptera, Leptophlebiidae, Hagenulinae, Hagenulini)

Here, I report a new species of the genus Neohagenulus Traver, 1938 from the Dominican Republic. The genus was believed to be endemic to Puerto Rico until now. Neohagenulus hodecekisp. nov. is described at the nymphal stage. Some discussion on the tribe Hagenulini is also provided.

Integrating tick density and park visitor behaviors to assess the risk of tick exposure in urban parks on Staten Island, New York

Background Public green spaces are important for human health, but they may expose visitors to ticks and tick-borne pathogens. We sought to understand risk and drivers of tick-preventative behavior in three popular parks on Staten Island, NY, USA by integrating tick hazard and park visitors’ behaviors. Methods From 20 May to 19 August 2019, ticks were collected via drag cloth sampling in multiple parks, sites, and habitats to estimate tick density. Human behavior was assessed by observing usage (time spent and activity type) in each site and habitat. To evaluate risk of tick exposure, we compared park usage by demographics across sites and compared individual exposure time per site and habitat. To assess visitors’ tick prevention behaviors, a knowledge, attitude, and practices (KAP) survey was administered. Results Three tick species (Ixodes scapularis, Amblyomma americanum and Haemaphysalis longicornis) were collected. The density of nymphs was heterogenous across parks, with the greatest density in unmaintained herbaceous habitats and trails. The fewest people entered the highest tick risk park and within-park locations. The KAP survey revealed that most respondents (N= 190) could not identify a nymphal stage tick when shown examples of various arthropods. Interviewees identified parks as the main location for tick exposure, but most believed they themselves had minimal risk for tick encounter. Consequently, many visitors did not conduct tick checks. People were most likely to practice tick checks if they knew multiple prevention methods and perceived a high likelihood of tick encounter. Conclusions By integrating acarological indices and park visitor behaviors we found a mismatch between the areas with higher tick densities and areas more frequently used by park visitors. However, this exposure risk varied among demographic groups and the type of activities. Moreover, the use of preventative measures was associated with the perceived probability of tick encounter and knowledge of tick habitat, which would modify the ultimate risk of tick encounter and disease given exposure. Our research is a first step towards identifying visitor risk, attitudes, and practices that could be targeted by optimized messaging strategies for tick bite prevention among park visitors.

Biological anomalies in the sugarcane leafhopper, Pyrilla perpusilla (Walker) due to parasitism by Fulgoraecia melanoleuca (Fletcher) (Lepidoptera: Epipyropidae)

Background Fulgoraecia melanoleuca (Fletcher) (Lepidoptera: Epipyropidae) (= Epipyrops or Epiricania melanoleuca) is an important koinobiont nymphal and adult ectoparasitoid of sugarcane leafhopper, Pyrilla perpusilla (Walker) (Hemiptera: Lophopidae). The study aimed to evaluate whether and to what extent this parasitoid effects the fitness of immature (five nymphal stages) and adult (♂ and ♀) stages of its host P. perpusilla. Results The nymphal mortality was significantly more in the younger nymphs, and it decreased as the host aged. The exposure of the first stage host nymphs to the parasitoid resulted in 100% mortality. However, the nymphal mortality rates in second, third, fourth and fifth nymphal stage were 94.0, 75.0, 38.0 and 41.0%, respectively. Furthermore, the longevity of surviving nymphs was prolonged significantly in the later stages. None of the parasitized first to fourth stage nymphs survived as normal adult. In case of the parasitized fifth nymphal stage, 18.0% adults were normal; however, their longevity was comparatively shorter than their un-parasitized counter parts. When male and female adults of leafhopper were offered to the parasitoid, significant differences were found in mortality of parasitized and un-parasitized adults for both sexes. Further, parasitoid-induced prolongation in the longevity of the surviving parasitized adults was also observed. Conclusions Overall, the parasitoid F. melanoleuca had detrimental effects on host fitness and thus played a significant role as a biological control agent in suppressing the sugarcane leafhopper population. This study will clarify host-parasitoid relationship, developing mass rearing protocol under laboratory conditions and implementing effective strategies for augmentative releases of parasitoids in biological control program against P. perpusilla in sugarcane ecosystem.

Vector competence of human-biting ticks Ixodes scapularis, Amblyomma americanum and Dermacentor variabilis for Powassan virus

Background Powassan virus (POWV; genus Flavivirus) is the sole North American member of the tick-borne encephalitis sero-complex and an increasing public health threat in the USA. Maintained in nature by Ixodes spp. ticks, POWV has also been isolated from species of other hard tick genera, yet it is unclear if these species can serve as vectors. Dermacentor variabilis and Amblyomma americanum share geographic and ecologic overlap with Ixodes spp. ticks and POWV transmission foci, raising the possibility that POWV could become established in these tick species and leading to range expansion and increased human risk. Therefore, we assessed the competency of Ixodes scapularis, D. variabilis and A. americanum for POWV lineage II (POWV II). Methods Larvae from all three species were co-infested on POWV-infected Balb/c mice. The engorged larvae were allowed to molt to nymphs and screened for the presence of POWV II RNA by reverse transcription-qPCR. Eight infected nymphs from each species were allowed to individually feed on a naïve mouse. Mice were screened for the presence of POWV II RNA to determine infection status. Results The results demonstrated that larvae from all three tick species were able to efficiently acquire POWV II via feeding on viremic mice, maintain infection through molting and successively transmit POWV to naïve mice at the nymphal stage at comparable rates across all three species. Conclusions Our findings reveal that non-Ixodes tick species can serve as competent vectors for POWV and highlight the potential role of these species in the ecology and epidemiology of POWV. Future studies examining the possible implications of these findings on POWV epidemiology and the adaptability of POWV in these new vectors are warranted. Graphical abstract

Description of nymph of Brasilocaenis atawallpa Lima, Molineri, Vieira, Pinheiro & Salles, 2019 (Ephemeroptera: Caenidae) and notes on its taxonomic status

Brasilocaenis atawallpa was recently described based on male imago from Colombian Amazon. The original description does not contain a designation of type specimens or locality, and it just states that the type series was studied in order to perform the cladistic analysis. In this context, we herein designate the lectotype and paralectotypes of B. atawallpa and describe its nymphal stage. The nymphs were associated to B. atawallpa by the male genitalia extracted from mature nymphs. The nymphal stage of B. atawallpa can be differentiated from others known nymphs of the genus by absence of pointed microspines on opercular gill, fore coxa without projection, middle coxa with well-developed and semicircular projection, hind coxa with finger-like projection, fore and middle tarsal claws without denticles and hind margin of the ninth sternite almost straight.

An Experimental Murine Model to Study Acquisition Dynamics of Tick-Borne Langat Virus in Ixodes Scapularis

Ixodes scapularis ticks acquire several pathogens from reservoir animals and transmit them to humans. Development of an animal model to study acquisition and transmission dynamics of these pathogens into and from ticks, respectively, is challenging due to the fact that in nature ticks feed for a longer duration and on multiple vertebrate hosts. To understand the complex nature of pathogen acquisition/transmission, it is essential to set up a successful tick blood feeding method on a suitable vertebrate host. In this study, we provide an evidence that murine model can be successfully used to study acquisition dynamics of Langat virus (LGTV), a member of tick-borne flaviviruses. Mice were inoculated intraperitoneally with LGTV that showed detectable viral loads in murine blood, skin and other tissues including brain. Both larval and nymphal ticks that were allowed to feed on murine host successfully acquired LGTV loads. Also, we found that after molting LGTV was transstadially transmitted from larval to nymphal stage. In addition, we noted that, LGTV down-regulated IsSMase expression in all group of ticks possibly for its survival in its vector host. Taken together, we provide an evidence on the use of murine model to not only study acquisition dynamics of LGTV but also to study changes in tick gene expression during acquisition of arboviruses into ticks.

Beech tree masting explains the inter-annual variation in the fall and spring peaks of Ixodes ricinus ticks with different time lags

Background: The tick Ixodes ricinus is an important vector of tick-borne diseases including Lyme borreliosis. In continental Europe, the nymphal stage of I. ricinus often has a bimodal phenology with a large spring/early summer peak and a smaller fall peak. While there is consensus about the origin of the spring nymphal peak, there are two alternative hypotheses for the fall nymphal peak, direct development versus delayed diapause. These two hypotheses make different predictions about the time lags of the correlations between the spring peak, the fall peak, and seed production (masting) by deciduous trees. Methods: To determine which hypothesis is most important for explaining the fall peak, we used data from a long-term surveillance study (15 years) on the density of I. ricinus nymphal ticks at 4 different elevation sites in an area of Switzerland that is endemic for Lyme borreliosis, and long-term data on the mast of the European beech tree from the literature. Results: I. ricinus nymphs had a bimodal phenology at the three lower elevation sites, but a unimodal phenology at the top elevation site. At the lower elevation sites, the density of nymphs (DON) in the fall was strongly correlated with the DON in the spring of the following year. The inter-annual variation in the densities of I. ricinus nymphs in the fall and spring were best explained by a 1-year versus a 2-year time lag with the beech tree masting index. Fall nymphs had higher fat content and are younger than spring nymphs. All of these observations are consistent with the direct development hypothesis for the fall peak of I. ricinus nymphs at our study site. Our study provides new insight into the complex bimodal phenology of this important disease vector. Conclusions: Public health officials in Europe should be aware that following a strong mast year, the DON will increase 1 year later in the fall and 2 years later in the spring and summer. Population ecology studies of I. ricinus should consider that the spring and fall peak in the same calendar year represent different generations of ticks.