Pathogenicity of Pratylenchus penetrans to Navy Bean (Phaseolus vulgaris L.)

The pathogenicity of Pratylenchus penetrans (root-lesion nematode) to Phaseolus vulgaris (navy bean) was evaluated in greenhouse experiments. Shoot and root fresh weight of cv. Sanilac plants were increased 4 and 21%, respectively, by an initial population density (Pi) of 25 P. penetrans per 100 cm³ soil. Leaf area and shoot fresh and dry weights were decreased by a Pi of 50 or more P. penetrans per 100 cm³ soil. A significant positive linear relationship existed between initial soil population densities of P. penetrans and final soil and root population densities of this nematode. Three dry bean cultivars, Sanilac, Seafarer, and Tuscola, were susceptible to P. penetrans, and yields were reduced by 43-76% when plants were exposed to a Pi of 150 P. penetrans per 100 cm³ soil. P. penetrans also reproduced on bean cultivars Saginaw, Gratiot, and Kentwood, but did not decrease bean yields, suggesting that these cultivars were tolerant to this nematode.     

Effects of Aufwuchs on Colonization by Simuliids (Simuliidae,Diptera)

While different studies investigated effects of surface properties on the adhesion and population dynamics of marine sessile organisms (Balanidae, Bryozoa etc.), little is known about sedentary freshwater macroinvertebrates. Artificial substrates were used to investigate the effects of Aufwuchs on density and distribution of colonizing blackfly larvae and pupae. Although, settlement of blackfly larvae often is said to be impeded by Aufwuchs or siltation, they colonized both bare substrates and those on which a thick Aufwuchs cover had developed. Often no differences in density appeared on substrates exposed for less than 6-9 d. Thus Aufwuchs apparently does not prevent initial settling of larvae. However, simuliid densities on Aufwuchs covered substrates declined after several more days of exposure, suggesting that surface properties may affect long-term settlement.     

Habitat use by mountain nyala Tragelaphus buxtoni determined using stem bite diameters at point of browse,bite rates,and time budgets in the Bale Mountains National Park,Ethiopia

We studied the habitat use of mountain nyala Tragelaphus buxtoni in the northern edge of the Bale Mountains Na- tional Park, Ethiopia. The aims of this study were to： （1） measure and quantify habitat-specific stem bite diameters of mountain nyala foraging on common natural plant species in two major habitat types （i.e. grasslands versus woodlands）, and （2） quantify the bite rates （number of bites per minute） and the activity time budgets of mountain nyala as functions of habitat type and sex-age category. We randomly laid out three transects in each habitat type. Following each transect, through focal animal obser- vations, we assessed and quantified stem diameters at point of browse （dpb）, bite rates, and time budgets of mountain nyala in grasslands versus woodlands. Stem dpb provide a measure of natural giving-up densities （GUDs） and can be used to assess fora- ging costs and efficiencies, with greater stem dpb corresponding to lower costs and greater efficiencies. The results showed that stem dpb, bite rates, induced vigilance, and proportion of time spent in feeding differed between habitats. In particular, mountain nyala had greater stem dpb, higher bite rates, and spent a greater proportion of their time in feeding and less in induced vigilance in the grasslands. In addition, adult females had the highest bite rates, and the browse species Solanum marginatum had the greatest stem dpb. Generally, grasslands provide the mountain nyala with several advantages over the woodlands, including of- fering lower foraging costs, greater safety, and more time for foraging. The study advocates how behavioural indicators and natural GUDs are used to examine the habitat use of the endangered mountain nyala through applying non-invasive techniques. We conclude that the resulting measures are helpful for guiding conservation and management efforts and could be applicable to a number of endangered wildlife species including the mountain nyala .     

Corn rootworm survey in North Dakota and a comparison of two sticky traps

Northern, Diabrotica barberi Smith & Lawrence, and western, D. virgifera virgifera LeConte, corn rootworms are major economic pests of corn, Zea mays L., in the United States. This research was conducted to determine the geographic distribution, abundance, and species composition of Diabrotica species in North Dakota, and to compare effectiveness of unbaited green Scentry™ Multigard and unbaited yellow Pherocon^® AM/NB sticky traps for monitoring. Fifty-one corn fields were monitored using traps from July through October of the 2013, 2014, and 2015 growing seasons for rootworm beetle activity. The overall species composition was 61% D. barberi and 39% D. v. virgifera. Both species were frequently captured, and the highest densities (i.e. >10 beetles per trap per week) were found in southeastern North Dakota. Low densities (i.e. <0.1 beetles per trap per week) of D. barberi were found in areas further north, but no D. v. virgifera were captured in those fields. The two different coloured sticky traps were not significantly different across 38 sites for D. barberi and across 21 sites for D. v. virgifera. However, green Scentry™ Multigard traps captured more D. barberi beetles than yellow Pherocon^® AM/NB traps at 68% of the 38 fields. In contrast, the yellow Pherocon^® AM/NB traps captured more D. v. virgifera beetles at 57% of the 21 fields. Findings also indicated that, although D. barberi was the predominant species in surveyed fields, populations rarely reached the economic threshold. Our study observed that economic populations of corn rootworms were infrequent among the field sites trapped in North Dakota. As a result, producers should scout fields regularly for corn rootworm populations levels to make sound pest management decisions. This knowledge can enable producers to effectively protect their crop when control is economically justified, and the information can also provide input cost savings when populations do not warrant control efforts.     

Host-Parasite Relationship of Meloidogyne chitwoodi on Potato

The soil fumigant 1,3-dichloropropene gave good to excellent control of the Columbia root-knot nematode, Meloidogyne chitwoodi, on potato, Solanum tuberosum L. Nonfumigant nematicides (aldicarb, fensulfothion, carbofuran, ethoprop, and phenamiphos) were less effective in controlling M. chitwoodi, since the nematode affects tuber quality more than quantity. Soil temperature during the growing season affected parasitism of M. chitwoodi on potato more than did the initial nematode population. There were positive linear correlations between degree-days and infected and galled tubers (r = 0.92), degree-days and nematode generations (r = 1.00), and infected and galled tubers and nematode generations (r = 0.91). Differences in degree-days and resultant nematode reproduction caused great variability in infection and galling of potato tubers during four growing seasons: 89% for 1979, 0% for 1980, 13% for 1981, and 18% for 1982, giving positive linear correlation (r = 0.99) between final nematode soil population (Pf) and percentage of infected and galled tubers. Corresponding increases in the soil populations of second-stage juveniles (J2) during the growing season were 9,700% in 1979, 170% in 1980,552% in 1981, and 326% in 1982. There was a negative linear correlation (r = -0.87) between initial soil J2 populations (Pi) and the degree of parasitism (infection and galling) of potato tubers, Pi being of secondary importance to degree-days.     

Densities of mammals in partially protected areas: the Katavi ecosystem of western Tanzania

1. In Africa the majority of conservation areas sanction some sort of human activities within their borders but few of them are part of community-based conservation schemes. The effectiveness of these state-owned, partially protected areas in conserving mammalian fauna is largely unknown.
2. Large and medium-sized mammal densities in three different sorts of partially protected area were compared to mammal densities in an adjacent national park in western Tanzania by driving 2953 km of strip transects over a 14-month period.
3. In a Game Controlled Area that permitted temporary settlement, cattle grazing and tourist big game hunting, mammal diversity and mammal densities were relatively high. In a Forest Reserve that permitted limited hardwood extraction and resident hunting, most large species were absent. In a third, Open Area that allowed settlement, cattle grazing, firewood collection and beekeeping activities, mammal diversity and densities were again low but some large ungulates still used the area seasonally.
4. The chief factors responsible for lowered mammal densities outside the Park were illegal hunting, especially in close proximity to town, and to a lesser extent, resident hunting quotas that were too high.
5. These data suggest that state-owned conservation areas permitting human activities within their borders cannot be relied upon as a means of conserving large and middle-sized mammals in Africa.
6. Two methods are being employed to ameliorate this problem in Africa: excluding people from conservation areas while upgrading ground protection effort, and initiation of community-based conservation schemes. As yet, however, very few quantitative data are available to evaluate the efficacy of these methods in enhancing mammal populations.     

Relationships between densities of previous and simultaneous foragers and the foraging behaviour of three bumblebee species

1. The local insect composition may be as important as the local floral composition for bumblebees' foraging behaviour. However, little is known about how the local abundance of insects affects the foraging patterns of individuals. 2. Using field observations, we studied the relationships between the local density of previous and simultaneous foragers and the local foraging behaviour of Bombus pascuorum, Bombus lucorum/B. terrestris and Bombus lapidarius while pollinating Centaurea jacea. 3. The number of bumblebees foraging in the plots was positively related to the number of new individuals arriving at these plots. The number of inflorescences contacted and the duration of visits were negatively related to the number of simultaneous foragers, but only in B. lucorum/B. terrestris. The effects of previous foragers on the behaviour of other bumblebees were species‐specific and variable in their direction. Such contrasting effects can be explained in terms of bumblebee species' abundances and functional similarity. In some cases, the effect of previous foragers increased with Centaurea density. 4. The local abundance of previous and simultaneous foragers affected the foraging behaviour of particular bumblebee individuals in complex ways. Future studies on local foraging behaviour might benefit from including the abundance of co‐foragers.     

Home Range and Movement Patterns of White-lipped Peccary (Tayassu pecari) Herds in the Northern Brazilian Amazon1

Two white-lipped peccary (Tayassu pecari) herds were radio-tracked for 5 and 13 mo, respectively, on Maracá Island Ecological Reserve, Roraima, Brazil. Home range size was 109.6 km² for the larger herd (130 animals) and 21.8 km² for the smaller herd (53 animals). Neither herd migrated or moved nomadically during the study period. The herd with the longer observation period increased its home range size during the flooded season by including new sites not used in the nonflooded season and continuing to use the nonflooded season sites. This pattern of simultancously using distinct seasonal ranges also occurred between the rainy and dry periods and the herd regularly and predictably returned to favored feeding sites. Population declines and disappearances in this study and others may have been caused by in situ mortality rather than by long-distance movements.