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Discussion on ground beetles and rove beetles as indicators of sustainable agriculture in Latvia: review
2013
Gailis, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Turka, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Ground beetles (Coleoptera: Carabidae) and rove beetles (Coleoptera: Staphylinidae) as predators of many pests and weeds in every crop are significant elements of integrated pest management. Worldwide studies show that ground beetles reflect different soil tillage methods, crop rotation, chemical and genetic pollution, usage of fertilizers and landscape fragmentation. All these factors are the parameters based on which it is possible to assess agriculture whether it is sustainable or not. Ground beetles also can indicate different farming systems and potentially serve as keystone indicators of pest abundance. Thus ground beetles can be good indicators of sustainable agriculture, but rove beetles have a good potential to do it. Researches on crop dwelling ground beetles and rove beetles have been done infrequently in Latvia. Mainly these are faunistic studies not paying attention to agricultural environmental factor effect to ground beetles and rove beetles. For using ground beetles and rove beetles as indicators of sustainable agriculture in Latvia, studies on these beetles reaction to different farming activities should be done. These studies must occur in different crops and different places of country, because ground beetle and rove beetle reflection to changes of agricultural environmental factors may be crop- and site - or even field-specific. Overview of literature on ground and rove beetles’ ecology in agroecosystems recorded in Latvia, other European countries and Northern America has been used for this study.
显示更多 [+] 显示较少 [-]Characterization of severe damages of spruce (Picea abies (L.) H. Karst.) stands in relation to soil properties
2011
Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Miezite, O., Latvia Univ. of Agriculture, Jelgava (Latvia) | Bardule, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Severe damages of spruce stands were found during recent years in several countries of the Baltic sea region. Characteristic indications of these damages are trees with brownish drying tops distributed across the whole compartment. During the first year only forests on drained organic soils suffer. In the second and third years, according to experiences gained in Lithuania, the damages move to other stand types. In Latvia, the first signals about the damages of spruce stands arrived from the company ''Rīgas meži'' in May, 2010. ''Rīgas meži'' found damaged stands in 2 forestries. The most of the damaged stands were on organic soils. The inspection of other forests by the State forest service identified similar damages in Southern part of Latvia as well as in other regions with considerable areas of organic soils. In August, 2010 ''Rīgas meži'' did their own inspection in Olaine and Tīreļi forestries and found out that 24% of spruce stands has characteristic signs of damages, and in 10% of stands dead or significantly damaged trees were found. Due to theses damages, about 300 ha of spruce stands were harvested in sanitary clear-felling in 2010. Spreading of spruce bud scale, Physokermes piceae (Schrnk.), is found to correlate with damages of spruce stands in Latvia and Lithuania. This pest is well known in both countries, but never before it caused any serious damages to spruce stands. In Sweden another bud scale insect (Physokermes inopinatus Danzig and Kozár) is found to be the reason for spruce damages.
显示更多 [+] 显示较少 [-]Birch growth responses to the insect injury simulations
2015
Araminiene, V., Lithuanian Research Centre for Agriculture and Forestry, Akademija, Kedainiai distr. (Lithuania) | Varnagiryte-Kabasinskiene, I., Lithuanian Research Centre for Agriculture and Forestry, Akademija, Kedainiai distr. (Lithuania)
The tree growth compensation followed by insect damage is important for tree survival. Insect damage by making 3 and 6 holes per each leaf, and clipping one third of a leaf were simulated for one-year old silver birch (Betula pendula Roth) seedlings once, at the beginning of the vegetation season. The height, aboveground and root biomass, root length, stem diameter and leaf area were measured for all damaged and control seedlings. The aim of the study was to examine the effects of different insect-damage simulations on silver birch growth. Our study demonstrated that leaf dry mass decreased in response to leaf perforations and clipping one third of leaf. However, at the end of the experiment, the cumulative dry mass reached the level of the control. We found no statistically significant effect on the aboveground and total biomass of damaged seedlings compared to the control. The leaf clipping decreased the leaf area and stem diameter compared both to the treatment with hole-damaged seedlings and the control. The induced birch growth response showed that tree seedlings were able to compensate their growth up to the control level after the insect damage in eight weeks.
显示更多 [+] 显示较少 [-]An overview of major pests of citrus in the Commonwealth Caribbean
1987
Reid, J.C. (Caribbean Agricultural Research and Development Institute, Mona (Jamaica))
Pests of major economic significance, their distribution in the Commonwealth Caribbean, the damage they cause and practices for their control are tabulated. The types of pests discussed are defoliators and foliage sap feeders and those causing damage to fruit, fiddler beetles, fruit flies, scale insects, and fruit piercing moths. The potentially serious pests of quarantine significance are summarised with their worldwide distribution and host plants other than citrus. The Mediterranean fruit fly Ceratitis capitata and the aphid vector of Tristeza, Toxoptera citricidus are significant
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