June 18, 2024
Biocontrol Agents

BioControl Agents: A Natural Way to Protect Crops and Enhance Crop Yield

Biocontrol provides sustainable pest management solutions by utilizing beneficial organisms. These agents help maintain ecological balance and reduce reliance on synthetic pesticides. Let’s explore some commonly used biocontrol agents and how they function.

Trichoderma Fungi for Disease Control

Trichoderma is a genus of opportunistic fungi that thrive in soil environments. Over 200 species of Trichoderma have been identified, with some exhibiting properties useful for managing plant diseases caused by other fungi. When applied to soil, Trichoderma competitively colonizes the root zone and secretes metabolites that inhibit or kill disease-causing fungi.

Some Trichoderma species, such as T. harzianum and T. viride, have shown promise in controlling various soilborne diseases on a wide range of crops. They attack fungal pathogens directly through antibiosis, predation, and competition for space and nutrients. Field trials demonstrate Trichoderma can reduce diseases like damping off, root rot, and wilts caused by Phytophthora, Fusarium, Rhizoctonia, and Sclerotinia.

Trichoderma works preventatively by colonizing the root surface early in plant development. Its metabolites produce a general resistance within plants, strengthening cell walls to barricade further infections. As a biofungicide, Trichoderma offers growers an organic option for integrated pest management programs, reducing but not eliminating the need for synthetic fungicides.

Nematode-Trapping Fungi to Suppress Root-Knot and Cyst Nematodes

Certain fungi have evolved trapping mechanisms to capture nematode pests in the soil. Two common genera used as biocontrol agents against plant-parasitic nematodes are Arthrobotrys and Dactylella. Species like A. oligospora and D. dactyloides produce structures like nets, rings, or adhesive knobs to snare nematodes that cross their hyphal growth in the rhizosphere.

Once nematodes are entangled, the fungi penetrate the cuticle and develop specialized feeding structures to consume the nematode contents. Field studies show nematode-trapping fungi significantly reduce populations of root-knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes on vegetables, ornamentals, row crops, and turfgrasses. Applied as a soil drench or incorporated into potting mixes, these fungi can help manage damaging nematodeinfestations in an environmentally-friendly manner.

Beneficial Insects for Pest Control

In addition to fungi, several insect species have proven effective as biocontrol agents For example, ladybird beetles in the genus Harmonia consume large numbers of aphids and other soft-bodied plant pests. Commonly utilized species include H. axyridis . which can destroy hundreds of aphids daily throughout their larval and adult lifecycles.

Parasitic wasps also serve as important natural enemies of many insect pests. Braconid wasps like Aphidius colemani lay their eggs inside the bodies of aphids, where the wasp larvaefeed and pupate, ultimately killing the host. Encarsia formosa prey on whiteflies, with each female capable of parasitizing dozens of nymphs or pupae over a 2-3 week lifespan.

Other beneficial insects used commercially for pest suppression include green lacewings, which consume aphids and small caterpillars, as well as predatory mites like Phytoseiulus persimilis or Neoseiulus californicus employed against spider mites and other plant-feeding mites. When mass-produced and applied to crops at key pest pressure periods, these natural enemies can help maintain low pest populations.

Augmentative Biological Control

Rather than relying on naturally occurring populations, augmentative biological control involves commercially purchasing and releasing large numbers of biocontrol agents. The goal is to achieve quick pest suppression through repeated and carefully-timed inundative applications of predators and parasites.

For example, periodic releases of Aphidius colemani wasps at field edges and into crop canopies is a common tactic used against aphid outbreaks in vegetables, ornamentals, fruit trees and nursery stock. Similarly, Encarias formosa, Neoseiulus cucumeris and other biocontrol mites are often applied preventatively or curatively on greenhouse crops affected by whiteflies and mites.

While initial costs are higher compared to conservation biological control alone, augmentative approaches tend to work faster in reducing pests to acceptable levels. Release rates must consider the existing pest infestation size and agent hunting rates to effectively establish control populations on the crop. Proper timing, application method and environmental conditions are critical for successful augmentation.

As illustrated, several fungi, insects and mites have demonstrated great potential to organically manage damaging crop pests without reliance on broad-spectrum chemicals. Used as part of an integrated pest management plan, biocontrol agents capitalize on natural biological processes to maintain pests at tolerable levels. Their subtle modes of action also pose less risk to humans, beneficial species and the environment. Looking ahead, further development of microbial inoculants, improved mass-rearing technologies and augmentative techniques aim to optimize utilizing beneficial organisms as sustainable biopesticides.

*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it