A fossil entomogenous fungus from Dominican amber

Summary A worker ant (Formicidae: Hymenoptera) embedded in amber (25 million years old) from the Dominican Republic was covered with an entomogenous fungus containing characters very similar to present day strains ofBeauveria bassiana. This represents the first report of a fossil insect-pathogenic fungus belonging to the class Deuteromycetes.     

Hymenaea protera sp.n. (Leguminosae,Caesalpinioideae) from Dominican amber has African affinities

Hymenaea protera is described from amber originating from La Toca mine in the Dominican Republic. The fossil species is characterized by the presence of reduced petals as well as distinctly clawed showy petals with cordate to reniform bases and a glabrous, verrucose ovary with long hirsute hairs at its base and along one margin. The fossil species most closely resembles the extantH. verrucosa Gaertner which occurs in East Africa and adjacent islands. These findings are interpreted as supporting a hypothesis that the genusHymenaea arose in the late Cretaceous on the combined South American-African continents and that Cretaceous and early Tertiary landmass movements were significant in determining the present amphi-Atlantic distribution of the genus. It is proposed that at least the majority, if not all, of the amber recovered from La Toca mine and other mines in the vicinity with similar-aged deposits originated fromH. protera.     

Adhesive grass spikelet with mammalian hair in Dominican amber: First fossil evidence of epizoochory

Discovery of a female spikelet of the grass genusPharus (Gramineae: Bambusoideae: Phareae) in association with mammalian hair in Dominican Republic amber provides the first fossil evidence of epizoochory. Hooked macrohairs on the lemma of the spikelet show that morphological modifications in grasses for dispersal by attachment to the surface of animals were present in the Late Eocene. The fossil also represents 1) the second-oldest undoubted macrofossil record of the Gramineae, 2) the earliest record of a fossil grass that can be assigned to an extant genus, 3) the earliest undoubted record of a member of the bamboo subfamily and 4) the only known fossil ofPharus.     

A new antlion from Dominican amber (Neuroptera: Myrmeleontidae)

A new fossil species of antlion,Porrerus dominicanus is described from Dominican amber. Extant species ofPorrerus are found only in South America and Panama.A review of the current knowledge of fossil Myrmeleontidae is provided,     

Adhesive grass spikelet with mammalian hair in Dominican amber: first fossil evidence of epizoochory.

Discovery of a female spikelet of the grass genus Pharus (Gramineae: Bambusoideae: Phareae) in association with mammalian hair in Dominican Republic amber provides the first fossil evidence of epizoochory. Hooked macrohairs on the lemma of the spikelet show that morphological modifications in grasses for dispersal by attachment to the surface of animals were present in the Late Eocene. The fossil also represents 1) the second-oldest undoubted macrofossil record of the Gramineae, 2) the earliest record of a fossil grass that can be assigned to an extant genus, 3) the earliest undoubted record of a member of the bamboo subfamily and 4) the only known fossil of Pharus.     

Mite parasitism of moths: Examples of paleosymbiosis in Dominican amber

Summary Two adult moths (families Gracillariidae and Tineidae) in Dominican amber each contained a pair of larval parasitic mites attached to their bodies. The larval mites were identified as belonging to the family Erythraeidae and represent the first fossil evidence of moths parasitized by mites. Phylogenic and evolutionary implications of this find are discussed in light of similar extant associations.     

The range of life in amber: significance and implications in DNA studies

A survey of the major fossiliferous amber deposits is provided, including ages and various categories of life forms reported from each. The frequence of occurrence of the major groups of plants and animals in these amber deposits is also given. Thus far, DNA from four insect and one plant species has been extracted from amber fossils. In the case of the stingless bee in Dominican amber, evidence of reproducibility is provided, since two independent laboratories isolated DNA from six or more different specimens of the same insect.Amber sources for DNA studies are listed together with their advantages and disadvantages. The important points are the availability of desired pieces, the proper identification of the fossil, verification of the amber deposit, the cost involved, and the feasibility of causing damage to the specimen. The availability of several types of amber (Mexican, Dominican, Baltic, Chinese, Canadian, Siberian and Lebanese) at four major sources (academic collections, commercial dealers, private collections and amber mines) is discussed. The scientific implications of obtaining DNA from amber inclusions are presented.     

Fossil habrotrochid rotifers in Dominican amber

Flask-shaped microfossils are reported from bracts of a moss in Eocene-Oligocene amber from the northern Dominican Republic. These microfossils are identical with the thecae of certain living moss-dwelling rotifers in the genusHabrotrocha (Bdelloidea), which have previously been reported as fossils only from Holocene peat. What may be an egg and a rotifer body fossil are associated with these thecae and further support the identification of these fossils withHabrotrocha; the fossils are almost identical to extantH. angusticollis. The parthenogenetic bdelloid rotifers have a longer evolutionary history than was previously thought; habrotrochid rotifers seem to have persisted for 35 million years with very little change in morphology or ecological role.     

Bdelloid rotifers in Dominican amber: Evidence for parthenogenetic continuity

Recently discovered representatives of the Class Bdelloidea from Tertiary amber from the Dominican Republic represent the oldest known fossils of the Phylum Rotifera. Assuming that the fossil bdelloids had a similar mode of reproduction as present day members of the Class (apomictic thelytoky), then contrary to current thought, some lines of parthenogenetic organisms are not doomed to an early extinction and have evolved built-in mechanisms for genetic diversity.     

Hair in Dominican amber: Evidence for tertiary land mammals in the Antilles

Summary A piece of amber from the Dominican Republic contained approximately 50 strands of mammalian hair. Based on its characteristics and the identification of two species of fossilized ectoparasites that were also present, it is probable that the hair belonged to a rodent. This find represents the earliest fossil remains of land mammals in the Antilles and lends support to the vicariance model of West Indian biogeography.     

The prey consumption and prey preference of the larvae of the mosquitoCulex (Lutzia) raptor on the larvae ofCulex quinquefasciatus

The maximum consumption of the larvae of the pest and vector mosquitoCulex quinquefasciatus by the predatory mosquitoCulex (Lutzia) raptor was studied at various instars of both the predator and the prey. The prey preferences of the predator when given lavae of different instars were also investigated. The IVth instar of the predator consumed the maximum number of Ist instar and the maximum biomass of IVth instar larvae of the prey. Instars I and II of the predator preferred the Ist of the prey; instars III and IV of the predator preferred instars II and III of the prey respectively.The predator consumed an average of 157.1 larvae during its whole larval period, when each instar of the predator was given its preferred instar of the prey.     

Brain factor fromGalleria mellonella (Lepidoptera) stimulating silk gland activity

Brain extracts from day 1–4 last instar larvae ofGalleria mellonella (Lepidoptera) stimulate RNA synthesis in cultured silk glands from day 3 last instar larvae. When the fibroin-synthesizing posterior parts of silk glands were incubated for 3 h in vitro in the presence of brain extract (0.1 brain equivalent), [³H]-uridine incorporation into RNA was stimulated more than twofold. The stimulating effect of brain extract showed a dose response relationship. It is suggested that the heat-resistant and protease-sensitive brain factor is a peptide.     

Effects of a juvenile hormone mimetic,fenoxycarb, on post-embryonic development of the European corn borer,Ostrinia nubilalis Hbn.

Summary The effect of a juvenile hormone mimetic, fenoxycarb, Ro 13-5223, was tested on the larval instars of the European corn borer,Ostrinia nubilalis, by dipping or topical application. When larvae were treated in instars 2, 3 or 4, the duration of the fifth instar was modified. More permanent and fewer supernumerary larvae were obtained when treatment occurred in the early instars. This non-neurotoxic compound exhibited a strong dose-dependent juvenile hormone type of activity when it was applied to last instar larvae. Fenoxycarb prevented the onset of pupation and produced supernumerary larvae and intermediates. Permanent larvae were obtained if fenoxycarb was applied on day 0 or day 1 of the last instar. The use of such a JH mimetic in the understanding of endocrine control of diapause is discussed.     

Role of low ecdysteroid levels in the early last larval instar ofBombyx mori

The relationship between juvenile hormone and ecdysteroid titers during the early stage of the last larval instar of the silkworm,Bombyx mori, was examined in this study. When larvae were fed 20-hydroxyecdysone-supplemented mulberry leaves throughout the last larval instar, 100% underwent supernumerary larval molting instead of metamorphosis. The application of juvenile hormone mimic during the early last instar did not induce supernumerary larval molting, but did delay metamorphosis. Temporal and quantitative ecdysteroid titer measurements revealed that in normal larvae the titers maintained very low levels (3–12 ng/ml) during the early stage of the last instar; however, in 20-hydroxyecdysone-treated larvae, levels ranging from 24 to 45 ng/ml were detected, and a major peak (246 ng/ml) was observed on day 6. These results show that very low ecdysteroid titer levels during the early stage of the last larval instar may play an important role in initiating decreases in juvenile hormone titers as well as in directing metamorphosis.     

Ultrastructure of 30–40 million year old leaflets from Dominican amber (Hymenaea protera,Fabaceae: Angiospermae)

Hymenaea protera leaflet fossils entombed in amber, dated at 30 to 40 million years (mine strata and exomethylene dating) were observed by both light and transmission electron microscopy. Ultrastructure preservation in these leaflets shows the presence of chloroplasts with thylakoid membranes, cell walls, mitochondria with associated endoplasmic reticulum, nuclei, and xylem tissue. Tissues show varying degrees of degradation; however, natural resin, which has perfused the cells, seems to maintain the structural integrity of the membranes and walls. We conclude that preservation of amber entombed organisms results from dehydration and slow fixative properties leaving the ultrastructure in excellent condition. These findings parallel reports on the exceptional preservation of amino acids and of DNA in amber-entombed organisms.     

Identification of 2-deoxyecdysone from the mite,Tyrophagus putrescentiae

2-Deoxyecdysone was purified from the miteTyrophagus putrescentiae and monitored by a radioimmunoassay. The compound was identified by GC-MS and LC-MS. This is the first report of an endogenous ecdysteroid from a mite.     

PCR jumping in clones of 30-million-year-old DNA fragments from amber preserved termites (Mastotermes electrodominicus)

DNA from 30-million-year-old amber preserved termites (Mastotermes electrodominicus) was PCR amplified with nuclear ribosomal RNA small subunit primers and cloned into the TA vector (INVITROGEN). We obtained several classes of recombinant clones as a result. AuthenticMastotermes electrodominicus clones were identified. The source of other classes of clones was identified as contaminants of the ancient DNA template. Several of the clones appeared to be chimeric in structure with half of the clone identical to the termite sequence and the other half identical to contaminant sequences. The phenomenon of PCR jumping was identified as a possible source for the chimeric clones.     

RH-5849, a nonsteroidal ecdysone agonist,does not mimic makisterone-A inDysdercus koenigii

The response of final instar nymphs ofDysdercus koenigii to topical application of the non-steroidal ecdysone agonist, RH-5849, was dose dependent. The candidate compound produced mortality even at moderate doses, but precocious adult development was not observed. Similar results were obtained after oral administration or injection. Conversely, injections of makisterone-A (the principal moulting hormone ofDysdercus) into 5th instar nymphs resulted in precocious adult development within 4 days. We conclude that RH-5849 does not mimic makisterone-A, as is the case with ecdysone, and that toxicity is mediated instead through non-endocrine targets in this insect species.     

In situ hybridization of rDNA on chromosomes of the honeybee,Apis mellifera L.

DNA probes containing the repeated rDNA region ofDrosophila melanogaster (coding for e.g. 28S and 18S rRNA) hybridized in situ to distinct regions of two heterologous mitotic chromosomes of the honeybee, identifying the nucleolus organizing regions (NORs). The method allows a rapid establishment of a physical map ofApis mellifera using other DNA probes ofDrosophila. This is the first report on well-defined chromosomal markers in the honeybee.