Annals of The Entomological Society of America最新文献

Information on the impacts of RNA viruses inhabiting insect hosts is scarce. Here, we studied the effects of a recently described RNA virus, Anagyrus vladimiri Reovirus, on its host, the parasitoid wasp Anagyrus vladimiri (Hymenoptera: Encyrtidae), an important natural enemy of mealybug pest species. We found that Anagyrus vladimiri Reovirus is maternally transmitted with very high fidelity but not paternally. Additionally, Anagyrus vladimiri Reovirus is horizontally transferred at a frequency of 23% from infected to uninfected wasp larvae that develop together inside the same mealybug host (superparasitism). To test the effects of Anagyrus vladimiri Reovirus on A. vladimiri, the virus horizontal transmission was utilized to establish Anagyrus vladimiri Reovirus-infected (RV⁺) and uninfected (RV^-) isogenic wasp lines, a method rarely applied and novel to RNA virus-parasitoid systems. Longevity, developmental time, sex ratio, and fecundity of RV⁺ and RV^-  A. vladimiri were very similar. Nonetheless, the egg hatching rate of RV⁺ wasps was markedly and significantly higher than that of RV^- wasps, especially in hosts that were not superparasitized. Additionally, significantly fewer encapsulation marks (the main form of mealybug immunity) were found around RV⁺ eggs inside parasitized mealybug hosts. Taken together, the data shows that Anagyrus vladimiri Reovirus may benefit A. vladimiri by counteracting the encapsulation immune response of the mealybug. However, why the numbers of offspring in both wasp lines are similar remains unclear. These findings present a rare example of interaction between an RNA virus and a parasitoid and may provide a tool for the improvement of biological control efforts.

Movement is a dynamic process that changes with ontogeny, physiological state, and ecological context. The results of organismal movement impact multiple dimensions of fitness, population dynamics, and functional interactions. As such, the study of movement is critical for understanding and conserving species. Bumble bees (Apidae: Bombus spp.) offer a powerful system to study multiple complexities of movement within a functionally important clade. Their life history includes distinct social and solitary phases, substantial intraspecific variation in body size, and multiple modes of movement behavior. These traits allow investigations of diverse concepts at multiple scales and during contrasting behavioral and motivational states-from individuals, to colonies, to populations, and among species. Despite extensive study as model organisms of fine-scale movements and optimal foraging theory, understanding of landscape-scale movements is more limited. This knowledge gap is especially troubling given global pollinator declines because such dispersive movements fundamentally affect how populations respond to landscape transformation, climate change, and restoration efforts. To build toward a refined understanding of the bumble bee movement, inform research, and assist conservation programs, we review foraging and dispersal movement across life stages and castes. Using an ontogenetic approach, we compare the movement motivation and capacity of individuals throughout colony development. Despite the growth in recent literature, much remains to be learned about the bumble bee movement, especially dispersive life stages. Focused effort on how movement varies with individual state such as nutrition and age, and comparative studies of species would all fill knowledge gaps with high potential to improve bee conservation and research.

Several metazoans live in extreme environments, but relatively little is known about the adaptations that these extremophiles have evolved to tolerate their conditions. The wetsalts tiger beetle, Cicindelidia hemorrhagica (LeConte) (Coleoptera: Cicindelidae), is found in the western USA, including the active geothermal springs in Yellowstone National Park (YNP). Here, we characterize behavioral, ecophysiological, and morphological traits of adult C. hemorrhagica living on hot springs in YNP compared to adults living in a non-hot spring environment in Idaho. Individuals in YNP behaviorally warmed and cooled themselves at surprisingly different frequencies than those in Idaho, with YNP individuals infrequently cooling themselves even though surface temperatures were greater because of geothermal activity and consequent bottom-up heating of individuals compared to the saline-flat habitat in Idaho. After a series of lethal thermal maxima and internal body temperature experiments, our results suggest that an explanation for the differential behavior is that the adult in YNP has evolved increased heat reflectance on the ventral portion of its abdomen. This increased heat reflectance seems to be caused by a physical feature as part of the exoskeleton's ventral abdominal plate, which likely protects the beetle by serving as a heat-resistant shield. The extreme conditions in YNP seem to have selected C. hemorrhagica to be among the most thermophilic insects known.

Targeting the distribution of germ-cell markers is a widely used strategy for investigating germline development in animals. Among these markers, the vasa (vas) orthologues, which encode ATP-dependent RNA helicases, are highly conserved. Previous studies have examined asexual (parthenogenetic) and viviparous embryos of the pea aphid Acyrthosiphon pisum using a cross-reacting Vas antibody. This study utilized a specific antibody against Ap-Vas1, a Vas orthologue in the pea aphid, to gain new insights into germline development. The Ap-Vas1-specific antibody facilitates earlier detection of germ-plasm assembly at the oocyte posterior, challenging the previous assumption that germ-plasm assembly begins only at the onset of embryogenesis. Treatment of oocytes and early embryos with cytoskeleton inhibitors suggests that germ-plasm assembly primarily depends on actin, in contrast to the fly Drosophila melanogaster, where both actin and microtubules are essential. Since pea aphids lack an orthologue of osk, which encodes the protein Osk responsible for anchoring Vas to the germ plasm in Drosophila, this suggests that pea aphids employ distinct mechanisms for osk- and microtubule-independent formation of the germ plasm. Moreover, the clustering of germ cells into germarium-like structures in the extraembryonic region before entering the embryos suggests a gonad formation process different from that in Drosophila, where germ cells begin to cluster into germaria after settling within the embryonic gonads. Therefore, the analysis of the Ap-Vas1 distribution provides a deeper understanding of germline development in asexual pea aphids, uncovering novel aspects of parthenogenetic and viviparous reproduction in insects.

Platygastrine wasps (Hymenoptera: Platygastridae) are parasitoids of gall midges (Diptera: Cecidomyiidae). They and their hosts are exceptionally abundant and speciose, with great relevance to agriculture and biodiversity research. Both groups are also "dark taxa," whose species identification and ecological associations are obscured by a history of taxonomic confusion and neglect. Verified host records are few in number and limited in scope. In order to understand host specialization, more records are needed. However, rearing Cecidomyiidae is challenging, as many species require living host tissue to complete development. There is no universal rearing method for Cecidomyiidae and their parasitoids. The present work applies an exploratory approach to rearing gall midges, with the aim of obtaining accurate host associations and parasitoid identifications. We obtained 5 species of Platygastrinae from reared material, 3 of which are identified and diagnosed. Platygaster demades Walker (= Platygaster marchali Kieffer, syn. nov. = Platygaster ornata Kieffer, syn. nov.) is not host-specific, attacking Cecidomyiidae on Rosaceae worldwide, including Filipendula ulmaria. Synopeas gibberosum Buhl apparently specializes on Dasineura ulmaria (Bremi) on F. ulmaria. Synopeas rhanis (Walker) is known only from galls of D. urticae (Perris), but may attack other midge species on Urtica dioica. Amblyaspis sp. emerged from Hartigiola annulipes (Hartig) galls on Fagus sylvatica, and Synopeas sp. was associated with Mycodiplosis sp. on Rubus sp. Illustrations, DNA barcodes, and distributions are provided. We discuss challenges to understanding "double dark taxa" interactions, implications for biological control, and possible solutions for future research on these important but neglected systems.

Pseudacysta perseae (Heidemann 1908) (Hemiptera: Tingidae) is a foliar pest of avocados. The effects of 6 fluctuating temperature regimens, which averaged 15, 20, 25, 30, 32, and 35 °C over a 24-h period, on the developmental and reproductive biology of P. perseae were investigated. Selected temperature cycles are representative of avocado production regions in California (US). Fluctuating temperature regimens had significant effects on P. perseae development times, fecundity, fertility, longevity, and survivorship rates. One linear model (Ordinary Linear) and 7 nonlinear regression functions (Beta, Brière-2, Lactin-2, Lobry-Rosso-Flandrois, Performance-2, Ratkowsky, and Weibull) were utilized to investigate the correlation between fluctuating temperature profiles and P. perseae development times. The Beta and Weibull models failed to converge. Model parameters, T _min, T _opt, and T _max, were estimated as 1.72 to 9.78 °C, 31.04 to 31.57 °C, and 34.05 to 39.38 °C, respectively. The thermal requirement for development, K, was estimated as 476.19 degree-days. At 32 °C, P. perseae females exhibited 4 egg-laying peaks around days 11, 35, 54, and 63 of life. A maximum daily average of eggs laid (i.e., fecundity) was 6.07 on day 35 and the average daily egg-laying rate was 3.08 eggs over a 69-day span. The maximum proportion of eggs that hatched (i.e., fertility) was 0.49 on day 31, and the average daily proportion of hatched eggs was 0.10. This study confirmed that P. perseae passes through 4 nymphal instars, not 5 as previously reported. In addition, sexual dimorphism with respect to the coloration of the fourth antennal segment is documented and is substantially darker in adult males.

Silpha obscura Linnaeus, 1758 (Coleoptera: Silphidae) is an omnivorous beetle species known for damaging agricultural crops, making it an important target for pest control strategies. Despite its impact, no studies have yet examined the anatomical and histological structures of the male digestive and reproductive tracts of S. obscura. Therefore, this study aimed to describe these structures in detail, which could provide insights into potential control methods. Twenty individuals were collected and histologically processed, with observations made using light microscopy. The digestive tract of S. obscura comprises 3 parts: a short foregut, a relatively long and wide midgut characterized by folds and numerous crypts of the blind intestine, and a narrow and elongated hindgut, which expands into the rectum. Malpighian tubules attach at the beginning of the hindgut, which continues with the ileum, colon, and rectum and ends at the anus. The male reproductive tract includes a pair of testes, a pair of efferent ducts (vas efferentia), a pair of deferent ducts (vas deferentia), a pair of seminal vesicles, 2 pairs of accessory glands, and the ductus ejaculatorius, which extends into the ejaculatorius bulbus. The reproductive tract terminates with the aedeagus. The testes consist of 2 lobes, each containing numerous follicles where spermatogenesis and spermiogenesis occur. This study provides detailed insights into the anatomy and histology of the digestive and male reproductive tracts of Silpha obscura. These findings may lead to new strategies for controlling this agricultural pest. Understanding these structures is crucial for further research.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a global invasive pest attacking soft-skinned fruit. The specialist larval parasitoid wasp, Ganaspis brasiliensis (Ihering), was recently approved in Europe and the United States for classical biological control releases against D. suzukii. Rearing methods are essential for supporting innundative releases but current methods using fresh fruit are costly and susceptible to variation in host quality. To develop an artificial rearing system, we first compared the performance and development of D. suzukii and G. brasiliensis on fresh raspberries and blueberries and then on various artificial diet shapes and volumes. Drosophila suzukii had 1-2 days shorter development times in raspberry than blueberry, whereas Ganaspis adult development time was similar in both fruit and averaged 25 days. Parasitism rates by G. brasiliensis were significantly higher in blueberry than raspberry in both small and large resource patches. We found that D. suzukii preferred to lay eggs in full sphere diet shapes than in flat diet circles or semisphere diet, and in the first trial with wasps parasitism was only found on D. suzukii larvae in the full sphere shape of raspberry diet. Comparison of parasitism on full sphere raspberry and blueberry diets found higher parasitism in raspberry compared to blueberry diet. Our results indicate potential for further improvement of artificial rearing systems for G. brasiliensis to allow more cost-effective and reliable rearing for biological control programs.

The study of social parasitism faces numerous challenges arising from the intricate and intranidal host-parasite interactions and the rarity of parasites compared to their free-living counterparts. As a result, our understanding of the ecology and evolution of most social parasites remains limited. Using whole-genome and reduced-representation sequence data, we conducted a study to fill knowledge gaps on host use, colony social structure, and population genetics of the facultative dulotic ant Formica aserva Forel. Our study reveals the remarkable ability of F. aserva to exploit at least 20 different host species across its wide geographic distribution. In some cases, one social parasite colony exploits multiple hosts simultaneously, suggesting a high degree of generalization even at a local spatial scale. Approximately 80% of the colonies were monogyne (with a single queen), with many exhibiting higher rates of polyandry compared to most Formica ants. Although we identified a supergene on chromosome 3, its association with colony structure remains uncertain due to the rarity of polygyny in our sample. Population genetic analyses reveal substantial geographic population structure, with the greatest divergence between California populations and those from the rest of the range. Mitochondrial population structure differs from structure inferred from the nuclear genome on a broad geographic scale, suggesting a possible role of adaptive introgression or genetic drift. This study provides valuable insights into the ecology and evolution of F. aserva, underscoring the need for further research to decipher the complexities of host interactions and the genetic mechanisms that regulate social structure.