Effect of irrigation on survival of third-stage Haemonchus contortus larvae (Nematoda: Trichostrongylidae)

During May through October 1976, samples of sheep pellets containing laboratory - reared, thirdstage Haemonchus contortus larvae were placed on irrigated and nonirrigated pasture plots at Provo, Utah. Periodically thereafter, grass clippings, soil scrapings, and remaining pellets were collected and baermannized to determine their comparative survival from the two environments. Water was added to the irrigated plots in accordance with a weekly sprinkling regime designed to furnish sufficient moisture to maintain pasture grass in this semiarid region. Meteorologic measurements were collected daily from both irrigated and nonirrigated sections.   During the year the nonirrigated section received a total of 131 mm of precipitation, whereas an additional 979 mm of water were added via sprinkling to the irrigated section. The monthly mean maximum temperature at soil surface under grass cover for the six - month study period on the irrigated section averaged 17.7 C less than on the nonirrigated section, and the corresponding soil moisture content remained 14.4 percent higher. A bioclimatograph of conditions on the nonirrigated section showed that none of the months during the year had levels of temperature and moisture which fell within the prescribed limits for optimum pasture transmission of H. contortus; on the irrigated section only October of the six - month study period failed to have suitable conditions for optimum pasture transmission. Larvae placed on the plots survived significantly longer and also in significantly greater numbers on the irrigated section, and irrigation enhanced the ability of larvae to migrate from pellets onto vegetation.     

Bionomics and control of the walnut spanworm, Phigalia plumogeraria (Hulst), on bitterbrush in Utah

In 1979, the walnut spanworm defoliated a 1 ha bitterbrush seed orchard near Nephi, Utah. No seed was produced for two years thereafter due to feeding damage. Life stages were described and illustrated. The female is brachypterous and incapable of flight. First instar larvae readily drop on their silk threads and probably are dispersed by wind. The insect has one annual generation. Moths laid an average of 159 eggs per cluster in April; larvae began to appear in early May and matured by the first week of June. The pupal period extended from June until mid-April. The parasitic bombyliid, Villa faustina (Osten Sacken), was reared from pupae. In April 1980, shrubs contained an estimated average of 1044 eggs each. On 19 May, larvae averaged 1.9 per 7.5 cm of twig and were in the first and second instar. On 20 May the population was controlled by spraying with Sevimol-4. Other potential host plants, as determined from greenhouse tests, are rose, ceanothus, mountain mahogany, serviceberry, and willow.     

Prairie dog colony attributes and associated vertebrate species

A survey of colony attributes and associated vertebrates on black - tail ( Cynomys ludovicianus ), Gunnison's ( C. gunnisoni ), and white - tail ( C. leucurus ) prairie dogs was made. A belt transect 1.6 km wide and 13,334 km long from Hobbs, New Mexico, to the Utah - Wyoming state line was surveyed. There were 47 colonies located (4760 ha comprising 2.2 percent) in the belt. Intercolony distances varied significantly. Three black - tail towns averaged 33 ha in area (SD = 26, range 10 – 61), II Gunnison's averaged 46 ha (SD = 43, range 16 – 150), and 33 white - tail towns averaged 125 ha (SD = 200, range 0.2 – 958). Badger activity was positively and significantly correlated to colony size and number of burrow openings on Gunnison's and white - tail towns. There were 107 vertebrate species and subspecies (one amphibian, 25 reptiles, 51 birds, 30 mammals) observed on prairie dog colonies. Results of our surveys are compared with prairie dog studies elsewhere. The role of prairie dogs and relationships to some vertebrates species are discussed.     

Growth and development of the western harvest mouse, Reithrodontomys megalotis megalotis

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis (Baird). Growth was characterized by several standard skull and body measurements and was partitioned into four phases of 1 – 3, 4 – 12, 13 – 22, and 23 – 70 days. Growth was best described by measurements of tail length, ear length, and dried eye - lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. The gestation period was 22 days, and the mean litter size was 3.83 (range 1 – 7). Sex ratio was 53.49 percent males to 46.51 percent females. Reproductive efficiency was 53.53 percent. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, postpartum estrous, year - round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis.       

Breeding biology of the Double-crested Cormorant on Utah Lake

Research on the nesting of the Double - crested Cormorant ( Phalacrocorax auritus auritus ) was undertaken to determine the breeding biology of the bird on Utah Lake, Utah County, and the possible effects that diking Provo Bay would have on the cormorants breeding there. In 1973, two colonies in Provo Bay were visited weekly to determine laying dates, incubation period, clutch size, and hatching dates. Another colony, located on the dike of the Geneva Steel Works Reservoir near Orem, was visited daily during the spring and summer of 1973. At this colony egg-laying occurred from 13 April to 17 May. The average clutch size was 3.8, and the egg length and width averaged 60.50 mm x 39.05 mm. The average period of incubation was 28 days, and 29.5 percent of the eggs hatched, beginning on 20 May and ending on 9 June. The young weighed an average of 36 gm at hatching with a beak length of 17 mm and tarsometatarsal length of 11 mm. These measurements increased to 1543 gm, 73 mm, and 58 mm, respectively, in 23 days. The cormorant population on Utah Lake may be severely reduced by the proposed diking of Provo Bay.     

Drumming behavior and life history notes of a high-altitude Colorado population of the stonefly Isoperla petersoni Needham

Late instar nymphs and adults of a Colorado Hudsonian zone population of Isoperla petersoni Needham and Christenson were studied during the summer and early fall months of 1998, when stream temperature ranged from 3.3° C to 8.9° C. Early and middle instar nymphs were absent from July to October, and nymphs attained maximum size in mid-August during the 2nd week of adult field presence, suggesting a univoltine-slow life cycle. Nymphs were carnivorous and fed primarily on chironomid larvae. Adults were present from August to mid-October, with peak numbers of adult males and females occurring in mid-September and late September, respectively. Fecundity of field-collected females averaged 94.1 ± 45.15 eggs per female in September ( N = 81) and decreased to 85.2 ± 57.6 in October ( N = 12). Drumming duets were 2-way (male-female), and female answers followed male calls (nonoverlapped) or began before completion of the male call (overlapped). Male calls averaged 11.1 ± 2.09 beats and female answers averaged 6.2 ± 2.99, with mean intervals of 118 and 58 ms, respectively. The average number of female answer beats increased from 5.3 ± 2.56 when duets were nonoverlapped, to 6.6 ± 3.08 when overlapped.     

Studies on the life cycle of the cicadellid bug Empoasca dolichi Paoli,in Southern Nigeria

Summary

Studies carried out on the biology of E. dolichi Paoli showed that its eggs are palegreen to creamy white, elongate and often curved, and have a mean length and width of 0·84 mm and 0·16 mm respectively. The egg-incubation period averaged 8·3 days under uncontrolled insectary conditions of 21–32°C and 45–95% relative humidity, while the life-cycle from egg to adult averaged 17·5 days. In the insectary, mating in E. dolichi usually started between the third and sixth day after adult emergence. Over 56% of observed individuals mated on the 4th day. The observed diurnal mating period was mainly within 05·30–09·00 hours and 16·00–20·00 hours local time, with an average copulation period of 65·7 min. The mean pre-oviposition period of 3·0 days for 23 mated females was significantly shorter than 4·0 days for 21 unmated females. An average of 116 eggs and 96 eggs were laid by mated and unmated females respectively, but the fecundity rate (3 eggs/day of total life-span) of mated females was significantly higher than that (2 eggs/day) of unmated females. Unmated females lived longer (mean=49·7 days) than mated females with a mean of 38·3 days. The average life-span for mated and unmated males was 31·0 and 32·4 days respectively. Insectary and field observations revealed that females of E. dolichi preferentially lay their eggs into the stems, leaf-veins and leaf petioles of cowpea plants. Only mated females of E. dolichi laid viable eggs, and the observed male: female sex-ratio of their progeny in the insectary was 1:1·04.     

Responses of the pea crab Pinnotheres taichungae to the life history patterns of its primary bivalve host Laternula marilina

At the Kaomei tidal flat in Taiwan, the population dynamics and growth of the bivalve Laternula marilina (Reeve, 1860) and responses of the symbiont pea crab Pinnotheres taichungae Sakai, 2000 to the life history patterns of its primary host were studied. The population cycle of the bivalve appears to be initiated by larval settlement occurring as early as late March culminated by die off at the beginning of December of the same year. The maximum host life span is estimated at nine months. Pea crabs, regardless of size, preferred utilizing bivalves with a shell length exceeding 28 mm. This suggests they only spend about three months as a commensal with the primary host because the latter may take five months from the time of settlement to grow to an average size of 32 mm. In response to the brief presence of large primary hosts, the pea crab may: (1) synchronize megalopal recruitment shortly prior to the presence of large primary hosts; (2) evolve a dual infestation mode, invading the bivalve during both invasive and hard stages; and (3) have a fast growth rate while commensal with the primary host.     

A self-pollination experiment in Pinus edulis

Controlled pollinations were performed on four pinyons ( Pinus edulis Engelm.) to compare the results of selfing and outcrossing. Final cone size was the same under both treatments. There was no significant difference in number of seeds per cone. Filled-seed yields averaged 14.4 percent in selfings and 90.5 percent in outcrossings. Relative self-fertility averaged about 15 percent, a level comparable with that of other pine species studied.     

Winter nutritive content of black sagebrush ( Artemisia nova ) grown in a uniform garden

Winter crude protein content, in vitro digestibility, and productivity were determined for seven accessions of black sagebrush ( Artemisia nova ) grown in a uniform garden. No significant differences were detected among the accessions for any of these attributes. Mean crude protein was 6.8% of dry matter. Accessional range was from 5.8% to 7.3%. Mean in vitro digestion was 54.8% of dry matter; accessional range, 51.9% to 57.2%. Mean current year's growth (a measurement of productivity) was 4.3 cm; accessional range, from 3.7 to 5.1 cm. In comparison to other winter forages, black sagebrush ranks high for winter levels of crude protein and very high in winter digestible dry matter but low in productivity.     

Micromammalian distribution and abundance in the Western Cape Province,South Africa,as evidenced by Barn owls Tyto alba (Scopoli)

The history of Western Cape mammalogy began almost 200 years ago with Thunberg () and has been augmented periodically ever since. The present paper follows Vernon () and Grindley et al. () in eliciting information from material in Barn owl Tyto alba (Scopoli) pellets. Analyses are based on identified and counted mandibles and maxillae. The Laminate vlei rat, Otomys laminatus Thomas and Schwann, and Krebs's fat mouse, Steatomys krebsii Peters, are shown to have wider distributions than were previously recorded. The Southern multimammate mouse, Mastomys coucha (A. Smith), is apparently expanding its range westwards, a move probably enabled by changes in vegetation due to farming practices. There appears to be some correspondence between proportional representation of some species and rainfall, either its amount per annum or its seasonality. Variation in alveolar length in Cape gerbils, Tatera afra (Gray), taken as a proxy for mean individual mass, suggests that mean size in this species may be influenced by rainfall seasonality. Although the Vlei rat, Otomys irroratus (Brants), is known to breed throughout the year, the present evidence indicates that in the West Coast National Park births peak in late spring and early summer, some two months after maximum rainfall. The Western Cape data support the concept that T. alba is a selective opportunist. Sample structure and co‐occurrence of species in individual pellets both show that in some cases the owls are more nearly opportunistic while in others they appear to be considerably more selective.     

On Schistosoma curassoni,S. haematobium and S. bovis from Senegal: development in Mesocricetus auratus,compatibility with species of Bulinus and their enzymes

A comparative study on the development of Senegalese isolates of Schistosoma curassoni, S. haematobium and S. bovis in hamsters is reported, together with the compatibility of these parasites with Bulinus spp. and enzymes of adult worms.

The mean worm return from 35 hamsters exposed to 100 cercariae each of S. curassoni was 11·5%, and of these 54% were paired, the remainder were single males. The growth and maturation of the worms were recorded from 40 to 100 days. The cross-over point (when paired females are of the same length as paired males) was reached at 42 days post-infection when the worms averaged 13·7 mm in length. The majority of tissue eggs (84·5%) were recovered from the liver, compared with 11% in the colon, 2·5% in the caecum and 1·6% in the small intestine. Estimates of the fecundity of paired females averaged 167 eggs/day per female worm. Snail-infection experiments showed S. curassoni to be compatible with B. umbilicatus, marginally compatible with B. senegalensis and incompatible with B. forskalii, B. jousseaumei and B. guernei. S. curassoni is marginally compatible with B. bavayi, B. beccarii, B. camerunensis and B. cernicus, (members of the B. forskalii group) and B. obtusispira, a species placed in the B. africanus group. The mean worm return from 35 hamsters exposed to 100 cercariae each of S. haematobium was 9·1%, and of these 46·7% were paired, 42·1% were single male worms and the remaining 11·2% were single female worms. The growth of the worms was recorded from 40 to 100 days, the maturation from 60 to 100 days. The cross-over point was reached at about 62 days post-infection when the worms averaged 8·3 mm long. The majority of tissue eggs (95·3%) was recovered from the liver, compared with 2·8% and 1·9% from the small intestine and colon, respectively. Estimates showed that the average fecundity of paired females was 86 eggs/day per female worm. Snail-infection experiments showed that S. haematobium is marginally compatible with B. senegalensis, but incompatible with B. guernei and B. forskalii. The mean worm return from 35 hamsters exposed to 100 cercariae each of S. bovis was 26·6%, and of these 53·1% were paired, the remainder were single males. The growth and maturation of worms were recorded from 40 to 100 days. The cross-over point was reached just before 40 days: at 40 days the paired males averaged 9·5 mm in length, the paired female 9·6 mm in length. The majority of eggs (53·1%) was recovered from the liver, compared with 20·7% from the small intestine and 19·8% from the colon.

Estimates of the fecundity of paired females averaged 95 eggs/day per female worm. Snail-infection experiments showed S. bovis to be compatible with B. guernei, fairly compatible with B. forskalii, and marginally compatible with B. umbilicatus. B. senegalensis appeared to be sensitive to S. bovis under laboratory conditions with large numbers dying after one week of exposure.

Enzymes in 3017 extracts of adult schistosomes, obtained from natural and laboratory infections, have been analysed by isoelectric focusing. Enzymes studied include glucose 6-phosphate dehydrogenase (G6PDH), phosphoglucomutase (PGM), lactate dehydrogenase (LDH), acid phosphatase (AcP), malate dehydrogenase (MDH), hexokinase (HK) and glucose phosphate isomerase (GPI). S. bovis was clearly differentiated from S. haematobium by patterns of G6PDH, GPI, HK and AcP. Similarly, S. bovis and S. curassoni were distinguishable by the different patterns of PGM, GPI, HK and AcP. S. haematobium and S. curassoni were differentiated by patterns of PGM and HK. Heterogeneity was seen in all species. In a natural infection of a sheep S. bovis and S. curassoni were found paired together.     

Reproductive biology of the tui chub, Gila bicolor, in Pyramid Lake, Nevada

Sex ratios for tui chubs ( Gila bicolor ), obtained from a sample of 3,384 fish, deviated significantly from the expected 1:1 ratio (chi - square, P 0.05). Spawning occurred from June to August, with estimated fecundities ranging from 6,110 to 68,933 ova. Females spawned after attaining a maximum (average) gonadal somatic index (GSI ― percent gonad weight/total body weight) of 9.1 percent and between surface water temperatures of 15.5 to 22.2 C. Males reached sexual maturity at age two, with most females maturing at age three. Consistent increases in fecundity were apparent with increasing length, weight, and age. Linear regressions between fork length and fecundity and weight and fecundity were highly significant (P     

Observations on the tube-building behaviour of the marine amphipod Cymadusa filosa Savigny (Crustacea: Ampithoidae)

The study reports on the tube-building behaviour of the corophioidean amphipod, Cymadusa filosa Savigny on two algae, Sargassum binderi Sonder and Ulva lactuca Linnaeus, based on experimental protocols using specimens in aquaria and in petri dishes. Cymadusa filosa was observed to construct open-ended, uniform diameter cylindrical tubes using amphipod silk, to bind together faecal pellets, detritus and fronds of Sargassum binderi or Ulva lactuca. Detailed studies of tube-building behaviour were carried out in petri dishes containing Ulva lactuca, using isolated specimens (5–13 mm in size) of different sexes for a period of one and a half months. Both males and females constructed tubes, and an average of four tubes were built by adults in 15 days. Females with young in the brood pouch did not construct new tubes following juvenile release. Juveniles were observed to build tubes using detritus and faecal material only within hours of being released from the brood pouch. The tubes of juveniles were either built on the walls of their mother's tubes or on an algal mass put together by the mother. There was a highly significant positive correlation between body length and tube length in males and females. There was no significant difference in the rate of tube length increase relative to body size between males and females, between males less than or more than 10 mm, or between females of less than or more than 10 mm. Tube-sharing was also observed between males and females.     

Winter nutrient content and deer use of gambel oak twigs in north central Utah

We examined winter nutritional quality of current-year bud and stem tissues from burned and unburned stands of Gambel oak ( Quercus gambelii Nutt.). Nutritional analyses were based on the amount of forage consumed by wintering mule deer. Deer use along the Utah Valley foothills averaged 6.25-10.7 cm of current-year growth. Of the tissues examined, post-fire bud tissue had the highest nutrient content, with a mean of 9.51% crude protein, 0.19% phosphorus, and 34.0% in vitro digestibility. Composite values (bud + stem) for unburned stands were slightly higher in crude protein and phosphorus and lower in digestibility than those reported in previous studies. Nutrient values from burned stands were significantly higher than those of unburned stands for all three measures. Tannin content of the burned-area regrowth was also higher. Overall forage value of Gambel oak to wintering mule deer is relatively low.     

Burrowing Owl foods in Conata Basin, South Dakota

Burrowing Owls ( Athene cunicularia ) were studied in a prairie dog town of southwestern South Dakota. Pellets regurgitated by Burrowing Owls contained a wide variety of prey remains. Insects, spiders, small mammals, and vegetation were the most frequent items identified in the pellets. Mammals were consumed most frequently during spring and early summer. Insects were consumed in large numbers during the entire period of this study, but they became more frequent in owl pellets during late summer and fall in association with a decline of mammal remains. Some prey items observed around owl nest sites were not found in the pellets examined. Possible secondary poisoning of some prey of Burrowing Owls has not produced any change in owl food habits, based on other studies reported in the literature.         

Spruce beetle ( Dendroctonus rufipennis ) outbreak in Engelmann spruce ( Picea Engelmannii ) in central Utah, 1986-1998

Extensive Engelmann spruce ( Picea engelmannii Parry ex Engelm.) mortality caused by the spruce beetle ( Dendroctonus rufipennis Kirby) has been occurring at the southern end of the Wasatch Plateau in central Utah. This spruce beetle outbreak is the largest recorded in Utah history. An extensive ground survey was conducted in 1996 on the Manti-LaSal National Forest, Sanpete and Ferron Ranger Districts, to document mortality and impact of a major spruce beetle outbreak on post-outbreak forest composition. In 1998 the same sites were resurveyed. Survey results indicate Engelmann spruce basal area (BA) loss averaged 78% in trees ≥5 inches diameter breast height (DBH) in 1996. Ninety percent of BA ≥5 inches DBH was lost within the same sites by 1998. Tree mortality of spruce ≥5 inches DBH expressed in trees per acre (TPA) averaged 53% in 1996. In 1998 TPA ≥5 inches DBH mortality averaged 73%. Before the outbreak live Engelmann spruce BA ≥5 inches DBH averaged 99 square feet, and TPA ≥5 inches DBH averaged 97. In the sites surveyed in 1996 and resurveyed in 1998, Engelmann spruce BA ≥5 inches DBH averaged 21 and 9 square feet, and TPA ≥5 inches DBH averaged 43 and 25, respectively. Overstory tree species composition changed from stands dominated by spruce to subalpine fir. Stand ratings for potential spruce beetle outbreaks were high to mostly medium hazard pre-outbreak and medium to primarily low hazard by 1998, as a result of reduction in average spruce diameter, total basal area, and overstory spruce.     

Regional and seasonal diet of the Western Burrowing Owl in south central Nevada

We examined diets of Western Burrowing Owls ( Athene cunicularia hypugaea ) based on contents of pellets and large prey remains collected year-round at burrows in each of the 3 regions in south central Nevada (Mojave Desert, Great Basin Desert, and Transition region). The most common prey items, based on percent frequency of occurrence, were crickets and grasshoppers, beetles, rodents, sun spiders, and scorpions. The most common vertebrate prey was kangaroo rats ( Dipodomys spp.). True bugs (Hemiptera), scorpions, and western harvest mice ( Reithrodontomys megalotis ) occurred most frequently in pellets from the Great Basin Desert region. Kangaroo rats ( Dipodomys spp.) and pocket mice (Perognathinae) were the most important vertebrate prey items in the Transition and Mojave Desert regions, respectively. Frequency of occurrence of any invertebrate prey was high (>80%) in samples year-round but dropped in winter samples, with scorpions and sun spiders exhibiting the steepest declines. Frequency of occurrence of any vertebrate prey peaked in spring samples, was intermediate for winter and summer samples, and was lowest in fall samples. With the possible exception of selecting for western harvest mice in the Great Basin Desert region, Western Burrowing Owls in our study appeared to be opportunistic foragers with a generalist feeding strategy.     

Stinger utilization and predation in the scorpion Paruroctonus boreus

The utilization of the stinger and the predatory technique of the scorpion, Paruroctonus boreus, was studied under laboratory conditions. During the study, 83 feedings were observed. Age of the scorpions and the percentage of prey stung by them were used to classify the scorpions into groups. The scorpions aged 13–61 days always stung prey. After 62 days the scorpions began to selectively utilize the stinger. Utilization declined until it reached 30 percent in the adult stage. The stinger is apparently necessary for prey capture only in the early life stages.       

Reproductive ecology of a Tibetan frog Nanorana parkeri (Anura: Ranidae)

Endemic to the Tibetan Plateau, Nanorana parkeri figures among the highest altitude amphibians in the world. The present work, which was conducted in an alpine marsh at 4300 m altitude, is the first report of the species’ reproductive ecology. The breeding season, as indicated by the presence of amplectant pairs and fresh eggs in ponds, lasted from early Mary to early July. The ratios of adult male to female were 1.3 in hibernation ponds and 2.3 in spawning ones. Males were smaller than females. Amplexus was typically axillary (81.7%), with a few exceptional amplexus in which a male clasped another male or object rather than gravid females. Scramble competition occurred in 6.8% of the normal amplexus located. The body sizes of amplexed couples correlated positively. Deposited eggs were attached to submerged plants solitarily (60.5%) or in small clusters (39.5%), and the scattered arrangement of individual eggs could be a strategy to ensure embryonic development in oxygen-poor environments. Clutch size averaged 189 [standard deviation (SD) = 64], and correlated positively with female body size; egg size averaged 2.18 mm (SD = 0.10), independent of female body size; both traits within a clutch were negatively related with each other even controlling for female body size. Relatively few and large eggs laid by the Tibetan frogs, compared with those by lowland aquatic-spawning anuran species, should be adaptive to the harsh high-altitude conditions. Larvae hatched from eggs after 16.4 days on average (SD = 5.8). Froglets emerged between late July and early August, but some tadpoles were present in winter. These findings may help to understand the evolution of amphibians in extreme environments and to protect these remote species.