Marilyn A. Houck

Chilocorine : heptacyclic alkaloid from a coccinellid beetle

Abstract A novel heptacyclic alkaloid, for which we coin the name chilocorine , was isolated from a ladybird beetle, Chilocorus cacti . It has a unique structure made up of two tricyclic substructures, 2-methylperhydro- 9b -azaphenalene and 3,4-dimethyloctahydro- 8b -azaacenaphthylene. The proposed structure is based on mass spectrometric, ultraviolet spectroscopic, and NMR evidence.

The potential role of phoresy in the evolution of parasitism: radiolabelling (tritium) evidence from an astigmatid mite

Using tritium as a radiolabel marker of interspecific fluid transfer, we present experimental evidence that the heteromorphic deutonymph of an astigmatid mite (Hemisarcoptes cooremani) acquires materials (at least water) directly from the haemolymph of its beetle host (Chilocorus cacti). This acquisition is above that obtained from atmospheric vapour. The material acquired from the host is necessary for the completion of the ontogeny of H. cooremani and is likely procured through the action of the caudal ventral suckers of the heteromorphic deutonymph (hypopus). On gross morphological criteria, this mite-beetle relationship was previously defined as phoretic (for dispersal). Scanning electron photomicrographs of the physical relationship between the hypopodes and the heetles shed light on the ‘parasitic’ nature of the hypopus of H. cooremani. Our findings are discussed in terms of the evolution of parasitism from a free-living astigmatid form. This transition into parasitism is facilitated by the heteromorphic hypopus and represents a classic ‘wolf-insheeps-clothing’ strategy. The heteromorph retains the characteristic phoretic morphology while exploiting the host in transit.

Spirocyclic Defensive Alkaloid from a Coccinellid Beetle

Abstract A new alkaloid, chilocorine B, was characterized from a coccinellid beetle, Chilocorus cacti. This compound represents the first spirocyclic example of the new “dimeric” alkaloid family whose structures are derived from two thirteen-carbon tricyclic subunits, 2-methylperhydro-9b-azaphenalene and 3,4-dimethyloctahydro-8bazaacenaphthylene.

Xeric survival without drinking by hypopodes of Hemisarcoptes cooremani (Acari: Hemisarcoptidae)

Abstract Hemisarcoptes cooremani (Thomas) (Acari: Hemisarcoptidae) is native to the southern United States, from California to Florida. Parasitic stages of the mites life cycle (i.e. larvae, protonymphs, tritonymphs and adults) have been used for the biological control of diaspidid scale insects which infest perennial vascular crops. A heteromorphic dispersal stage (hypopode) differs from all other stages in the life cycle in that it is well sclerotized. All other stages are relatively soft-bodied and sheltered from desiccation by the cap (and velum) of their invaded diaspidid prey. The hypopode lacks an oral cavity and foregut and is therefore prevented from imbibing water, as water becomes available from the environment, and as it awaits the arrival of its phoretic dispersal host (Chilocorus cacti). A water balance profile was constructed on the hypopode of H. cooremani to better understand how this stage survives extended periods of water stress in hot dry climates. A high dehydration tolerance was not apparent. The major survival element in dry environments appears to be water retention (low net water loss rate) and a small water pool. The high critical transition temperature and suppressed activation energies for water loss suggest that the enhanced water conservation is due, in part, to the sclerotized cuticular armor, particular to this stage in the life cycle.

Allergenicity of the mite Hemisarcoptes cooremani

BACKGROUND A researcher experienced allergic symptoms while working with the astigmatid mite Hemisarcoptes cooremani cultured on scale insects. This mite is a predator of scale insects that often parasitize many perennial vascular plants in orchards, gardens, and ornamental nurseries worldwide; therefore, orchard and ornamental nursery workers and gardeners may be exposed to this mite. OBJECTIVE We investigated the possible allergenicity of H. cooremani and the cross-reactivity between it and other allergy-causing astigmatid mites. METHODS Serum from a subject who experienced allergic symptoms while working with H. cooremani was analyzed for IgE and IgG to proteins in an extract of this mite and of other astigmatid mites known to cause allergic reactions. The serum was used to probe proteins fractionated by SDS-PAGE or precipitated by CIE using rabbit antiserum. In addition, the subjects serum was used to directly precipitate proteins in extracts of H. cooremani and other mite species. RESULTS SDS-PAGE and immunoblotting of proteins in an H. cooremani extract showed the reference serum contained IgE directed at 16-kD and 19-kD proteins. Crossed radioimmunoelectrophoresis reaction showed that the subjects serum contained antibody that precipitated a protein in an H. cooremani extract and that IgE bound to this protein. The proteins in an extract of H. cooremani did not precipitate when reacted with rabbit antisera against the dust mites D. farinae, D. pteronyssinus, and E. maynei, or the storage mites B. tropicalis, L. destructor, and T. putrescentiae. This indicated there was no cross-reactivity between H. cooremani and these mites. CONCLUSION These results indicated that an extract of the mite H. cooremani contained at least two prominent IgE binding proteins that were not present in the other astigmatid mites. Thus, H. cooremani is the source of unique allergenic proteins and allergy to this mite may develop in orchard and ornamental nursery workers and gardeners.

MORPHOMETRIC ANALYSIS OF SEVEN SPECIES OF POCKET GOPHERS (GEOMYS)

Interspecific morphometric variation was assessed in seven species of pocket gophers ( Geomys ). One hundred and seven characters, representing cranial and post-cranial characters were examined in 131 individuals. A basic premise of this study was that previously under-represented appendicular, skeletal, and mandibular structures may provide informative data for species discrimination. Principal components analysis established that ca. 50% of among-group variation in males and females was attributable to size as determined by the magnitude, sign, and distribution of character loadings on the first principal component. Sexual dimorphism in these species primarily is a function of size, and shape differences are less important in the discrimination of gender. A phenogram of all species, constructed from the Mahalanobis distances, indicated that G. texensis and G. bursarius were most similar and G. breviceps and G. personatus were distinct compared with other species of Geomys . Other taxa were not discriminated completely in multivariate space. The low level of morphological evolution does not reflect the level of genetic differentiation reported by other investigators, suggesting that many species of Geomys may represent cryptic species.

Juvenile Greater Roadrunner (Cuculidae) Killed by Choking on a Texas Horned Lizard (Phrynosomatidae)

comments on the status of Bufo cavifrons and Bufo cristatus. Herpetologica 53:268-286. MENDELSON, J. R., III. 1998. Geographic variation in Bufo valliceps (Anura: Bufonidae), a widespread toad in the United States and Middle America. Scientific Papers, Natural History Museum, The University of Kansas 8:1-12. SCHMIDT, K. P. 1953. A check list of North American amphibians and reptiles, Sixth ed. American Society of Ichthyologists and Herpetologists, Chicago, Illinois. SMITH, H. M., AND E. H. TAYLOR. 1950. Type localities of Mexican reptiles and amphibians. University of Kansas Science Bulletin 33:313-380.

Phoresy by Hemisarcoptes (Acari: Hemisarcoptidae) on Chilocorus (Coleoptera: Coccinellidae) : influence of subelytral ultrastructure

The non-phoretic stages of mites of the genus Hemisarcoptes are predators of the family Diaspididae. The heteromorphic deutonymph (hypopus) maintains a stenoxenic relationship with beetles of the genus Chilocorus. The mites attach to the subelytral surface of the beetle elytron during transport. There is variation in mite density among species of Chilocorus. Both Hemisarcoptes and Chilocorus have been applied to biological control programmes around the world. The objective of this study was to determine whether subelytral ultrastructure (spine density) plays a role in the evolution of symbiosis between the mite and the beetle. The subelytral surfaces of 19 species of Chilocorus and 16 species of Exochomus were examined. Spine density was determined for five subelytral zones: the anterior pronotal margin, medial central region, caudoventral tip, lateral distal margin and epipleural region. Spine density on the subelytral surface of Chilocorus and Exochomus was inversely correlated with the size of the elytron for all zones except the caudoventral tip. This suggests that an increase in body size resulted in a redistribution of spines and not an addition of spines. The pattern of spine density in Exochomus and Chilocorus follows a single size–density trajectory. The pattern of subelytral ultrastructure is not strictly consistent with either beetle phylogeny or beetle allometry. The absence of spines is not correlated with either beetle genus or size and species of either Chilocorus or Exochomus may be devoid of spines in any zone, irrespective of body size. A general difference between species of Chilocorus and Exochomus is the fact that while spine density in Chilocorus is clinal relative to the size gradient, Exochomus is dichotomous and likely to have either many spines or no spines in a particular zone. No species of Chilocorus was completely devoid of spines. Five species of Exochomus had no spines at all, thus making it difficult to interpret the primary function of the subelytral spines in a general way. Within the genus Chilocorus, spine density may play a synergistic role in host association. Based on morphological evidence alone, these findings lead to the hypothesis that the species of Chilocorus that would be most conducive to biological control application in conjunction with Hemisarcoptes would be Chilocorus cacti, Chilocorus distigma, Chilocorus fraternus, Chilocorus orbus, Chilocorus tristis and, to a lesser extent, Chilocorus bipustulatus.

Maintenance of water balance in the twice-stabbed ladybird beetle, Chilocorus cacti (Coleoptera: Coccinellidae), despite heavy infestation by the mite, Hemisarcoptes cooremani (Acari: Acariformes)

Abstract Large numbers (up to 400/elytron) of heavily sclerotized deutonymphs of the mite, Hemisarcoptes cooremani, attach to the elytral hypodermis of desert-inhabiting beetles, Chilocorus cacti, for transport and feeding. A potential physiological benefit to beetles of tolerating attached mites in dry habitats may be a reduction of the surface area-to-volume ratio of exposed evaporatory tissue (decreased water loss), especially during flight. In this study, infested beetles were observed to have identical water balance characteristics as nonparasitized beetles, indicating that mites provide no extra, mechanical advantage to the beetle in terms of increased water conservation. The beetles were not distinguished by having a low water content, high tolerance for dehydration, or ability to absorb water vapor from the atmosphere. Their ability to retain water (low net water loss rate that compares favorably to values for diapausing beetles that maximize water conservation during quiescence), however, helps a...

Parasitic mites of pocket gophers (Rodentia: Geomyidae) from Texas, USA

Abstract One-hundred and three pocket gophers (57 females and 46 males) of the genus Geomys (7 species and 9 subspecies) and the genus Cratogeomys (1 species and 2 subspecies) from Texas, USA were examined for acarine parasites. Data recorded included: locality, date, host gender, parasite density, host-parasite co-occurrence, and mite demographic stage. A total of 1,222 mites were collected. Of the 103 hosts collected, 73.8% were parasitized by mites from 8 taxa. All host taxa were infested with mites. Rodents were identified to species using chromosomal analysis. Transportation to the laboratory from the collection site required a holding time and processing required an additional confinement period. The influence of interim confinement on parasite density was examined. Parasite density was inversely correlated with duration of host captivity. Geomys texensis Merriam had the highest rate of infestation (96%). The mite Echinonyssus geomydis (Keegan) was collected most frequently (n = 380). Androlaelaps geomys (Strandtmann) had the most diverse host range and was collected from the most host taxa (10 taxa). Euschoengastoides sp. and Pseudoschoengastia farneri showed the greatest specificity, being collected from only one host taxon (G. texensis). The chiggers Euschoengastoides sp., Hyponeocula deserticola Tanigoshi and Loomis, Parasecia gurneyi campestris (Loomis), and P. farneri Lipovsky (previously found only on birds, other rodents, and reptiles) represent host records for pocket gophers.