Biological control or biocontrol is use of population of natural enemies (predators, parasitoid and pathogens) by human to control or regulate the pest population. Some approaches are designed to enhance natural enemy population density by improving their living condition. Biological control is part of integrated pest management and the system approach is to reduce the use of chemical pesticide and to control the pest which have become resistant to pesticide. Whereas, the natural biological control is control or reduction of pest population by natural enemies in their ecosystem without any human interference.
The three main techniques of biological control (Bale et al., 2008) are classical, conservation and augmentative biological control.
- Classical biological control (CBC): Inoculative biological control is also known as classical biological control (DeBach 1964). The target pest, if is an invasive non-native species and its natural enemy is introduced, the method is known as classical biological control. Natural enemies are collected from the area of origin of pest and then released in area where pest were accidently introduced (van Lenteren 2012). Classical or inoculative biological control is applied in new area where pest have arrived without their natural enemies. Small number of natural enemies are introduced with the presumption that they will reproduce and their young ones will continue to provide pest control.
- Conservation biological control: Conservation biological control is applying practices that can maintain survival and efficacy of the pathogens, predators and parasitoids (natural enemies). The population and diversity of natural enemies increases in response to conservation measures and plant, habitat diversification (Begg et al., 2017). A way to achieve conservation biological control is by providing habitat and resources to natural enemies. Lu et al. (2014) reviewed various type of plant derived food (nectar and pollen) for the natural enemies and use of flowering plants to maximize biological control of insect pest. The predatory insects and parasitoids are effective in controlling herbivores population in diverse systems of vegetation than in simple ones (Russel 1989). The vegetation diversity (Poveda et al., 2008) has been suggested to disrupt pest ability to locate plant or repel the pest and increase the mortality of pest.
- Augmentative biological control: Augmentative biological control is periodical release of natural enemies to manage plant pest. Natural enemies are mass reared in biofactories for release in large numbers to obtain immediate control over pests (van Lanteren 2012). It’s a commercial activity because of the large scale production and regular release of natural enemies. If pest control by natural enemies is insufficient then additional natural enemies can be released. Release rate is crucial and therefore should be carefully considered. Inundative release method involves natural enemies which are mass reared and periodically released in large number to control pest. This method is applied where the potential viable breeding population of natural enemy is not achievable and rapid control is required at an early infestation stage. Seasonal inoculative release is where natural enemies are collected, mass reared and periodically released where many pest generation occur with each growing season. Minkenberg (1989) studied biological control of the leafminer Liriomyza spp. on tomato plant by seasonal inoculative releases of Diglyphus isaea. Large number of natural enemies are released to immediately control and also to build up their population for control throughout the growing season (van Lenteren 2000). Eight factor that limits the impact of release rate on effectiveness of augmentative biological control (Crowder 2007) are:
- Prey availability
- Initial settlement rates
- The method of release
- The timing of releases
The ‘new species association’ biological control approach is based on the ecological principle in which a natural enemy is used that has not coevolved with a pest (O’Connell et al., 2012).
New association biological control of native species differ from classical biological control in several ways (Van Driesche et al., 2008). New association biological control is not advisable for native plant even those that become weeds.
Adopt approach to enhance services provided by the natural enemies based on ecological principle instead of chemical pesticide.
Bale, J.S., van Lenteren, J. C. and Bigler, F. 2008 Biological Control and Sustainable Food Production. Phil. Trans. R. Soc. B 363(1492): 761–776
Begg, G. S., Cook, S. M., Dye, R., Ferrante, M., Franck, P., Lavigne, C., Lövei, G. L., Mansion-Vaquie, A., Pell, J. K., Petit, S., Quesada, N., Ricci, B., Wratten, S. D. and Birch, A. N. E. 2017 A Functional Overview of Conservation Biological Control. Crop Protection 97: 145-158
Crowder, D. W. 2007 Impact of Release Rates on the Effectiveness of Augmentative Biological Control Agents. J Insect Sci. 7(1): 15
DeBach, P. 1964 Biological Control of Insect Pests and Weeds. Chapman and Hall, London, pp. 844
Lu, Z- X., Zhu, P-Y., Gurr, G. M., Zheng, X-S., Read, D. M. Y., Heong, K- L., Yang, Y-J. and Xu, H-X. 2014 Mechanisms for Flowering Plants to Benefit Arthropod Natural Enemies of Insect Pests: Prospects for Enhanced Use in Agriculture. Insect Sci. 21(1): 1–12
Minkenberg, O. P. J. M. 1989 Temperature Effects on the Life History of the Eulophid Wasp Diglyphus isaea, an Ectoparasitoid of Leafminers (Liriomyza spp.), on Tomatoes. Ann. Appl. Biol. 115(3): 381 – 397
O’Connell, D.M., Wratten, S.D., Pugh, A.R. and Barnes, A-M. 2012 ‘New Species Association’ Biological Control? Two Coccinellid Species and an Invasive Psyllid Pest in New Zealand. Biological Control 62(2): 86 – 92
Poveda, K., Gomez, M. I., and Martinez, E. 2008 Diversification Practices: Their Effect on Pest Regulation and Production. Rev. Colomb. Entomol. 34 (2): 131–144
Russell, E. 1989 Enemies Hypothesis: A Review of the Effect of Vegetational Diversity on Predatory Insects and Parasitoids. Environ. Entomo. 18 (4): 590-599
Van Driesche, R., Hoddle, M. and Center, T. 2008 Types of Biological Control, Targets and Agents in “Control of pests and weeds by natural enemies” A Introduction to Biological Control. Blackwell Publishing Limited, Malden. Chapter 2, pp 4 – 8
van Lenteren, J.C. 2012 The State of Commercial Augmentative Biological Control: Plenty of Natural Enemies, but a Frustrating Lack of Uptake. Biocontrol 57: 1–20
van Lenteren, J.C. 2000 Success in Biological Control of Arthropods by Augmentation of Natural Enemies in “Biological Control: Measures of Success”, Gurranti, G. and Wratten, S. (eds.), Kluwer Academic Publishers. Chapter 3, pp 77-103