High productivity gel diets for rearing of Queensland fruit fly, <Emphasis Type="Italic">Bactrocera tryoni</Emphasis>

The Queensland fruit fly or ‘Q-fly,’ Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is Australia’s most damaging insect pest of horticulture. The sterile insect technique (SIT) is being developed as a sustainable approach to management of Q-fly. New larval diets are needed for economical production of millions of artificially reared sterile flies that are required for use in SIT. Solid diets that incorporate biological bulking agents present problems of variable quality and waste disposal. Liquid diets emerged as a promising alternative, but these also suffer drawbacks, including separation of components, fermentation and need for cleaning and regular replacement of substrates that support developing larvae. The present study considers whether two promising liquid diet formulations might be improved by incorporating agar (0, 0.25, 0.5, 1.0 and 1.5%) to create semiliquid or gel diets that maintain consistent composition, suppress fermentation, negate the need for supporting substrates and minimize waste. Overall, gel diets containing greater than 0.5% agar outperformed liquid diets (0% agar) and semiliquid diets (0.25% agar) of identical nutritional composition, especially in terms of development rate and productivity. Flies from the two tested diet formulations differed in flight performance, and this likely reflects differences in concentration of wheat germ oil and/or the type of yeast used. Overall, gel diets show great promise for rearing of Q-fly, overcoming many of the constraints of both traditional solid diets and more recently developed liquid diets. There is now a need for larger-scale trials that test and refine these diets for use in operational SIT settings.     

Natural biological control of <Emphasis Type="Italic">Halyomorpha halys</Emphasis> by native egg parasitoids: a multi-year survey in northern Delaware

Halyomorpha halys (Stål) is a highly polyphagous plant pest native to eastern Asia. Since its accidental introduction to the USA in the mid-1990s, it has spread across North America and caused serious economic damages. Chemical control has been a widely applied management strategy which is not sustainable on a long-term basis. A nine-year survey using sentinel and naturally laid H. halys was conducted to investigate the extent of natural biological control by parasitoids in managed and non-managed landscapes in northern Delaware, USA. Naturally laid egg masses of native pentatomids were collected to compare the resident parasitoid complex to the one attacking H. halys eggs. Mean parasitism rates of sentinel eggs were below 6% in any given year of the survey with a grand mean of 1.79%. Parasitism of naturally laid H. halys eggs was higher than that of sentinel eggs, but there was no significant difference in parasitism between years and the grand mean was 4.31%. Parasitoid species richness on sentinel and naturally laid H. halys eggs was similar but both were lower than the richness on native pentatomid eggs. H. halys eggs were parasitized by eight species in the genera Anastatus, Trissolcus, Telenomus, and Ooencyrtus. The level of parasitism by native egg parasitoids is insufficient to provide long-term control of H. halys. Trissolcus japonicus (Ashmead), an Asian egg parasitoid that has been recovered in the USA in several locations since 2014, may be the most promising candidate for long-term biological control of H. halys.     

Species proportions by area in mixtures of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) and European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) dominate many of the European forest stands. Also, mixtures of European beech and Scots pine more or less occur over all European countries, but have been scarcely investigated. The area occupied by each species is of high relevance, especially for growth evaluation and comparison of different species in mixed and monospecific stands. Thus, we studied different methods to describe species proportions and their definition as proportion by area. 25 triplets consisting of mixed and monospecific stands were established across Europe ranging from Lithuania to Spain in northern to southern direction and from Bulgaria to Belgium in eastern to western direction. On stand level, the conclusive method for estimating the species proportion as a fraction of the stand area relates the observed density (tree number or basal area) to its potential. This stand-level estimation makes use of the potential from comparable neighboring monospecific stands or from maximum density lines derived from other data, e.g. forest inventories or permanent observations plots. At tree level, the fraction of the stand area occupied by a species can be derived from the proportions of their crown projection area or of their leaf area. The estimates of the potentials obtained from neighboring monospecific stands, especially in older stands, were poorer than those from the maximum density line depending on the Martonne aridity index. Therefore, the stand-level method in combination with the Martonne aridity index for potential densities can be highly recommended. The species’ proportions estimated with this method are best approximated by the proportions of the species’ leaf areas. In forest practice, the most commonly applied method is an ocular estimation of the proportions by crown projection area. Even though the proportions of pine were calculated here by measuring crown projection areas in the field, we found this method to underestimate the proportion by 25% compared to the stand-level approach.     

Effects of forest harvesting on runoff and sediment characteristics in the Hyrcanian forests,northern Iran

Loss of canopy cover by forest harvesting generally increases the average surface runoff volume and sediment. Selective cutting (single and group selection method) is the most usual forest harvesting method in the Hyrcanian forests in the north of Iran. The purpose of this study is to find the effect of selective logging technique on the hydrological behavior of runoff and sediment in the Kheyrud forests located in northern Iran over 1 year. Four treatments were implemented: natural forest without harvesting (C), forest with selective harvesting (H) and area without canopy cover (WC) and skid trail (S). Three types of data were measured in each plot including soil chemical and physical properties, runoff and sediment load after each rainfall. The results indicate significant differences (P ≤ 0.05) in runoff generation and sediment production with respect to the treatments cover. The runoff in all treatments showed relatively similar response to rainfall, while the highest runoff and sediment were observed in skid trails, and the area without canopy cover (1.13 and 0.62 mm, and 1.2 and 0.51 g m^?2), averagely. In contrast, the natural forest without harvesting and the forest with selective harvesting treatments exhibited the lowest amounts of runoff (0.2 and 0.44 mm) and sediment (0.1 and 0.17 g m^?2), averagely. Implementation of low logging technique was useful to control the effects of logging on the runoff and sediment yield.     

Understanding the naturalization of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> in Portugal: a comparison with Australian plantations

Despite the potential utility of a biogeographical approach to understanding the naturalization of exotic species, studies using this approach are scarce. Eucalyptus globulus is an economically important Australian tree species that has become naturalized in a number of countries where it was introduced. Portugal is an ideal territory to study the naturalization of E. globulus owing to: a long introduction history, the antipodal location compared to Australia and the large cultivated area. Wildling density was assessed in 116 E. globulus plantations in central Portugal through 213 transects established along plantation borders. Boosted regression trees were used to model the influence of plantation-scale variables. Results from this survey were compared with data obtained in plantations from seven Australian regions, where a similar sampling protocol had been used. In Portugal, wildlings were more abundant in plantations that were: located in moist aspects, coppiced, with older tree stems and corresponding to intermediate site growth indexes. The overall density (127 plants ha^?1) was 14.9 times higher than in the Australian estate, but this ratio was reduced to 3.1 in a more comparable subset of unburnt, first rotation plantations. A generalized linear model fitted using a dataset combining the two surveys showed that country influenced wildling density, together with plantation rotation and stem age. These results provide insights into the naturalization of a widely cultivated tree species, pointing to a fundamental role of the introduction history, possibly acting along with the biogeographical characteristics of the introduced range.     

Effects of thermal-time artificial scarification on the germination dynamics of black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) seeds

The aim of this study was to determine the efficiency of methods for the artificial scarification of black locust seeds based on the influence of the air and liquid nitrogen temperatures. Three populations were selected for the analyses: a managed tree stand, a selected seed stand and a seed orchard. Samples of 200 seeds (4 × 50) were randomly selected. Before scarification, the seeds were stored at ?70 °C for 24 h. Nine different scarification treatments were evaluated. To calculate the germination capacity and the dynamics of germination, observations were made on days 3, 5, 7, 10 and 14 after treatment. For statistical analyses, we used repeated measures analysis of variance. The obtained results indicated that the highest scarification efficiency for black locust seeds occurred in the treatment in liquid nitrogen and in an air temperature range of 85–90 °C. The provenance of seeds had a significant effect on the dynamics of germination. Thermal methods and the use of liquid nitrogen can be alternatives to the labour intensive methods of cutting the seeds or using measures that require specialised equipment.     

Regulation,formalization, and smallholder timber production in northern Central Java,Indonesia

Forest Law Enforcement, Governance, and Trade agreements between the EU and countries that grow tropical timber aim to complement, alter, or generate new regulatory mechanisms that ensure the legality of timber products. These regulatory changes affect pre-existing policies and practices within timber production networks. The Indonesian-EU Voluntary Partnership Agreement was signed in 2013, and legality verification is scheduled to become mandatory for all smallholders by the end of 2017. Using grower surveys conducted in the Jepara regency of Central Java (n = 204), we generate information on who Jepara smallholders are, what timber species they are growing, and how programs that provide free and discounted seedlings contribute to STP. We use these data to understand how STP operates and how Sistem Verifikasi Legalitas Kayu (SVLK), the Indonesian method for timber legality verification, will affect STP networks and producers. We find that resource provision and oversight of source documentation increase formalization within STP. Our discussion details four policy-relevant insights for promoting STP amid continued formalization.     

Factors influencing biomass and carbon storage potential of different land use systems along an elevational gradient in temperate northwestern Himalaya

We observed the influence of five different altitudes and prevailing agro ecosystems on biomass and carbon sequestration potential in Kullu district of Himachal Pradesh, India. The study area had five prevailing land uses viz., agriculture, agro-horticulture, horticulture, silvi-pasture, and forest at four elevations representing about 1 °C temperature change. The results showed that maximum total biomass of 404.35 Mg C ha^?1 was accumulated by forest landuse and followed a decreasing trend in the order as forest > silvi-pasture > agro-horticulture > horticulture > agriculture. Similar trends were also seen with respect to biomass carbon (C) density and C-sequestration potential of different land uses. Biomass and carbon density potential enhanced with the increase in the altitudinal ranges from 1100–1400 to 2000–2300 m a.s.l. But, the rate of C-sequestration potential enhanced from 1100 to 2000 m and declined at 2000–2300 m a.s.l. Maximum carbon density (393.29 Mg C ha^?1) of both plant as well as soil was displayed by the forest-based land use systems situated at an altitudinal gradient of 2000–2300 m a.s.l. The rate of C-sequestration was maximum (2.17 Mg ha^?1) in the agro-horticulture at 2000–2300 m a.s.l. This study brings out the potential of different land use systems influenced by varying factors on their C-sequestration potential in western Himalayan elevation gradient, thereby providing useful information for effective management in a climate change mitigation and carbon budget.