Tolerance range

Analyze Problem in Ecology

TITTLE         : The effect of temperature and humidity changes on insects development their impacton forest ecosystems in the expected climate change

AUTHOR      : Tomasz Jaworski, Jacek Hilszczański, Forest Research Institute, Department of Forest Protection, Sękocin Stary, ul. Braci Leśnej 3, 05–090 Raszyn, Poland, 2013

Ongoing  climate  change  is  mainly  evident  as  increased  in  average  temperature.  It is expected to  have a significant impact on world’s biomes, with forest ecosystems especially vulnerable to these changes. The effect of  climate  change  on  forests  is  both  indirect,  through  its  impact  on  various  tree  species  of  different  ecological requirements, and direct, through its impact on all living components of the forest ecosystem. Among the latter, insects are the group of the greatest importance, including species detrimental to forest health. The impact of climate change on forest insects may be reflected in their distribution, phenology, activity, number of generations and, indirectly, through impact on their natural enemies. Predicting the future direction and pace of the climate change, as well as direct and indirect consequences of its effect on forest insects is difficult and often subject to considerable inaccuracy.

The influence of climate on insects

The basic climate parameters, i.e. temperature and humidity. Insects  as  poikilothermic  animals  change  their activity  visibly  depending  on  the  temperature  of  the surrounding environment. Above is effect of the change on temperature and humidity

·         Increasing the temperature to the thermal optima level causes acceleration of the insect metabolism. Its influences their activity increase. It  can  also  result  in insects  dispersion  increase  in  the  forest  environment, as well as more frequent oviposition and possibility of colonising larger number of host plants.

·         Temperature also influence on a length of larval development has been  observed  under  laboratorial conditions  for  two  significant  species  of  native foliophages:  the  nun  moth, Lymantria monacha (L.) and the gypsy moth Lymantri adispar(L.) (Karolewskiet al.  2007). In both cases. Temperature increase has had an influence on reducing growth period, from egg phase to pupa. 

·         Average temperature increase causes faster growth and can have an influence on generation number increase of these species. As a result, biological life cycle is shortened and the larva number on the one host plant, as well as outbreaks frequency, increases. Negative influence of the average temperature increase on the forest management  is observed with regard to European spruce bark beetle Ips typographus(L.), which is the most dangerous pests of this tree species in Europe, including Poland (Jönsson et al. 2007; Netherer, Schopf 2010). Temperature increase in  winter  can  cause  survival  increase,  what occurs especially in northern and upper range borders, where  extreme  low  temperature  usually  causes  higher mortality within the population. However, many species is  not  able  to  finish  the  developmental  cycle  or  to continue  feeding  in  spring  without  sufficient  number of low temperature days.

·    Temperature and humidity change can influence insects indirectly by changes in host plants metabolism and physiology. Although a moderate temperature increase (as well as and CO2 concentration) can cause a decrease  in  food  quality  for  some  foliophages,  as a result of nitrogen level decrease in foliage, as well as an increase in the synthesis of secondary metabolites.

·       The lower food quality of plants in result of drought causes longer development of phytophages what determines higher probability of the attacks of natural enemies, such as predators and parasitoids (Coviella, Trumble 1999; Rouault et al. 2006). Higher temperature as the stimulating factor can cause activity increase of natural enemies and their faster development (Netherer, Schopf 2010).

·       In higher temperature in early spring can cause earlier development of oak leaves what results in disruption of synchronisation between the process and the hatching of winter moth larvae (Visser, Holleman 2001). Faster plant growth in spring and longer vegetation can be beneficial to these phytophagous species that develop inside plant organism. It applies to some European spruce bark beetle species that can have extra generation during the year.

The  strategy  of  adaptation  of  forests  (natural ecosystems)  and  forestry  (practices  and  forest management) to climate change with regard to influence of insects should be considered in all its bearings. Regarding stability and stress  resistance  of  the  forest  stand, including insect attacks, adjusting species composition of  the  stand  to  habitat’s  conditions  is  important.  It is  hoped  to  use  natural  tree  (species,  populations, phenotypes)  resistance  against  insect  attack;  however, these  actions  should  be  preceded  by  a  research  on resistance  heredity. Including phenology of trees  and their pests in forest plans can prevent or limit defoliation.

Refferences

Coviella C. E., Trumble J. T. 1999. Effects of Elevated Atmospheric Carbon Dioxide on Insect-Plant Interactions. Conservation Biology, 13 (4): 700–712.

Jönsson A. M., Harding S., Bärring L., Ravn H. P. 2007. Impact of climate change on the population dynamics of Ips typographus in southern Sweden. Agricultural and Forest Meteorology, 146: 70–81.

Karolewski P., Grzebyta J., Oleksyn J., Giertych M. J. 2007. Effects of temperature on larval survival rate and duration of development of Lymantria monacha (L.) on needles of Pinus silvestris (L.) and of L. dispar (L.) on leaves of Quercus robur (L.). Polish Journal of Ecology, 55 (3): 595–600.

Netherer S., Schopf A. 2010. Potential effects of climate change on insect herbivores in European forests – General aspects and the pine processionary moth as specific example. Forest Ecology and Management, 259: 831–838.

Rouault G., Candau J.-N., Lieutier F., Nageleisen L.-M., Martin J.-C., Warzée N. 2006. Effects of drought and heat on forest insect populations in relation to the 2003 drought in Western Europe. Annals of Forest Science, 63 (6): 613–624.

Visser M. E., Holleman L. J. M. 2001. Warmer spring disrupt the synchrony of oak and winter moth phenology. Proceedings of the Royal Society. London. B, 268: 289–294.

Reflection

I know if the activities are carried out by humans, animals and also industry, producing gas emissions in the form of CO2. Levels of CO2 the higher, making the temperature of the Earth increases. The Earth's increasing temperature and result in a decrease in humidity on Earth, this climate change result in distribution and the number of population that are in the forest. If more and more of the insect which is a pest for flora in the forest, it will damage the balance of forest ecosystems. One way so that the forest can adapt to maintain the stability of the forest such as overseeing the insect attack, the composition of each population in the forest. If they don't follow up then the stability of the ecosystem will be disturbed and more pest outburst and some species of insects will continue to die even threatened with extinction.