Insect monitoring and forecasting
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- Insect life tables are used to track stage-specific mortality in insect populations. They show the number surviving and dying at each life stage. - Insect monitoring involves regular surveillance of insect populations, damage, and movement to assess pest levels and predict problems. Various monitoring techniques are used including visual counts, traps, and nets. - Insect forecasting makes predictions about future pest outbreaks and suitable control times based on past and present monitoring data, especially weather impacts on pests. Both short and long-term forecasts are used.
Insect monitoring and forecasting
- 1. Powerpoint Templates Page 1 Insect monitoring and forecasting
- 2. Powerpoint Templates Page 2 outline • Insect life table • Insect monitoring • Insect forecasting
- 3. Powerpoint Templates Page 3 Insect life tables • A "life table" is a kind of bookkeeping system that ecologists often use to keep track of stage-specific mortality in the populations they study. • The use of life tables as a convenient method for summarizing the amount of mortality occurring in each generation of an insect population was proposed by Morris and Miller (1954). • It is an especially useful approach in entomology where developmental stages are discrete and mortality rates may vary widely from one life stage to another.
- 4. Powerpoint Templates Page 4 Cont.. • To create a life table, an ecologist follows the life history of many individuals in a population, keeping track of how many offspring each female produces, when each one dies, and what caused its death. • After amassing data from different populations, different years, and different environmental conditions, the ecologist summarizes this data by calculating average mortality within each developmental stage.
- 5. Powerpoint Templates Page 5 Example
- 6. Powerpoint Templates Page 6 Cont.. • A life table can be created from the above data. Start with a cohort of 200 eggs (the progeny of Mrs. Average Female). • This number represents the maximum biotic potential of the species (i.e. the greatest number of offspring that could be produced in one generation under ideal conditions). • The first line of the life table lists the main cause(s) of death, the number dying, and the percent mortality during the egg stage. • In this example, an average of only 100 individuals survive the egg stage and become larvae. • The second line of the table lists the mortality experience of these 100 larvae: only 10 of them survive to become pupae (90% mortality of the larvae). • The third line of the table lists the mortality experience of the 10 pupae -- three-fifths die of freezing. • This leaves only 4 individuals alive in the adult stage to reproduce. If we assume a 1:1 sex ratio, then there are 2 males and 2 females to start the next generation.
- 7. Powerpoint Templates Page 7 Insect monitoring • Insect Monitor means to maintain regular surveillance on insects aspects such as population, biology, movement among many others. • Why monitor ? Often it may be difficult to identify the insects causing the particular damage. If this is the case, the next option available is to examine the symptoms of crop damage. Use the diagnostic tool to help to identify the insect pest causing the damage.
- 8. Powerpoint Templates Page 8 Importance of monitoring • To assess the pest situation and determine what sort of pest activity is occurring • For decision making • To predict pest problems before they occur
- 9. Powerpoint Templates Page 9 Monitoring techniques and procured Monitoring guide lines a. What to look for: Presence and evidence of pests Evidence of damage Nature of damage Where the damage is found Are there still pests present in the damaged area Presence of natural enemies Evidence of potentially contributing activities to the pest problem If unrecognized pests are found, samples should be collected and brought to the county extension office.
- 10. Powerpoint Templates Page 10 Frequency of monitoring b. Determined by the biology of the pest Determined by the crop, if a crop has a low threshold of damage, more intensive monitoring may be needed at regular intervals (weekly and maybe more frequently when a pest approaches a borderline to becoming a threat to a crop) c. Size of area to monitor Depends on the crop, the farm size, and the pest Enough to provide good field representation or coverage Depends on the degree of accuracy required and the resources available The field is surveyed in a pre-arranged pattern, such as walking in an S, U, Z, V or X shape
- 11. Powerpoint Templates Page 11 Cont.. d. Record keeping: Accurate records are important for decision making and for evaluating trends in pest populations season to season If a monitoring form is developed, it should provide information on: Both harmful and beneficial insects Identification of the field and the sample date Sample method Units of sample, e.g. insects per tree, infected fruits per plant
- 12. Powerpoint Templates Page 12 Monitoring methods a.Types of monitoring techniques i. visual counts over a representative area – - counting the number of pests present per plant, per leaf, per fruit, per terminal, per area bases – - damage counts which estimate pest population per plant, per area or per fruit (pre and post harvest) ii. pheromone traps – - sticky traps which use pheromone bait to attract insects iii. sweep nets – - need to use a standardized sweep – - sampling locations need to be consistent – - in some cases sampling times need to be consistent iiii. field history, look for patterns of pest problems.
- 13. Powerpoint Templates Page 13 Cont.. • b. monitoring for insect pests – i. visual counts – ii. sweep nets – iii. pheromone traps
- 14. Powerpoint Templates Page 14 Pest Forecasting Forecasting • This is the process of making predictions of the future based on past and present data and most commonly by analysis of trends. • Forecasting of pest incidence or outbreak is based on information obtained from pest surveillance. Uses - Predicting pest outbreak which needs control measure - Suitable stage at which control measure gives maximum protection Two types of pest forecasting a. Short term forecasting - Based on 1 or 2 seasons b. Long term forecasting - Based on affect of weather parameters on pest
- 15. Powerpoint Templates Page 15 Objectives of Pest Surveillance • To know existing and new pest species • To assess pest population and damage at different growth stage of crop • To study the influence of weather parameters on pest • To study changing pest status (Minor to major) • To assess natural enemies and their influence on pests • Effect of new cropping pattern and varieties on pest
- 16. Powerpoint Templates Page 16 Survey • Conducted to study the abundance of a pest species Qualitative survey - Useful for detection of pest Quantitative survey - Useful for enumeration of pest Two types of survey - Roving survey and fixed plot survey Roving survey • Assessment of pest population/damage from randomly selected spots representing larger area • Large area surveyed in short period • Provides information on pest level over large area
- 17. Powerpoint Templates Page 17 Cont.. Fixed plot survey • Assessment of pest population/damage from a fixed plot selected in a field. The data on pest population/damage recorded periodic from sowing till harvest. e.g. 1 sq.m. plots randomly selected from 5 spots in one acre of crop area in case of rice. From each plot 10 plant selected at random. Total tillers and tillers affected by stem borer in these 10 plants counted. Total leaves and number affected by leaf folder observed. Damage expressed as per cent
- 18. Powerpoint Templates Page 18 Sampling Techniques Absolute sampling - To count all the pests occurring in a plot Relative sampling - To measure pest in terms of some values which can be compared over time and space e.g. Light trap catch, Pheromone trap Sticky trap Light trap Pheromone traps
- 19. Powerpoint Templates Page 19 Methods of sampling a. In situ counts - Visual observation on number of insects on plant canopy (either entire plot or randomly selected plot) b. Knock down - Collecting insects from an area by removing from crop and (Sudden trap) counting (Jarring) c. Netting - Use of sweep net for hoppers, odonates, grasshopper etc.
- 20. Powerpoint Templates Page 20 d. Norcotised collection - Quick moving insects anaesthesised and counter. e. Trapping : Light trap - Phototropic insects Pheromone trap - Species specific Sticky trap - Sucking insects Bait trap - Sorghum shootfly - Fishmeal trap Emergence trap - For soil insects
- 21. Powerpoint Templates Page 21 Cont.. f. Crop samples Plant parts removed and pest counted e.g. Bollworms
- 22. Powerpoint Templates Page 22 Stage of Sampling • Usually most injurious stage counted • Sometimes egg masses counted - Practical considerations • Hoppers - Nymphs and adult counted
- 23. Powerpoint Templates Page 23 Cont.. • Sample Size - Differs with nature of pest and crop - Parger sample size gives accurate results • Decision Making - Population or damage assessed from the crop - Compared with ETL and EIL - When pest level crosses ETL, control measure has to be taken to prevent pest from reducing EIL.
- 24. Powerpoint Templates Page 24 Thank you!