Category: news
Date published: June 24, 2016

Managing Caterpillar infestations in your greenhouse

In recent times, growers have experienced sustained infestation of their crop by caterpillars of various species. This has led to significant losses to their enterprises with rejects associated with this pest now emerging among the top when compared with other insect pests.This has become a growing concern among growers especially in the flower industry, hence a need to highlight some of its management practices.

Damage

Caterpillars are the larval stage of a butterfly or moth. Characteristically, they have biting mouthparts, and a large number of them are important crop pests. Butterflies are usually more noticeable since most of them fly by day. Moths on the other hand are generally night flying and so less obvious, but their larvae cause more economic damage to plants than butterfly larvae.

Caterpillars are a major constraint to food, fiber and horticultural crop production systems. Depending on the species, they chew irregular holes in plant leaves and flowers or entirely consume seedlings, young shoots and buds. Caterpillars are voracious feeders and can severely retard the growth of young plants or reduce the aesthetic value of produce in case of cut flowers and fruits.  

Management

a. Cultural control

Ensure good sanitation of the greenhouse and its environs. Remove any weeds and plant debris that may serve as host to the caterpillars. Where applicable, it is advisable that you install insect netting in all ventilation openings to prevent adults from entering the greenhouse. In addition, repair any holes or damage in the plastic walls and/or roof material and use clean planting material and plants.

b. Scouting and monitoring

Deploy PHERODIS pheromones mounted on Delta traps to identify the species and ensure timely intervention. We recommend, that you set up the traps at a rate of 10 delta traps per hectare where the adults are expected to be. Check the traps on a weekly basis and change pheromone dispensers every four to six weeks. Initially, if you are not sure which species of moth you are dealing with, set up a couple of traps with different pheromones to help with identification.

c. Mass trapping

PHERODIS pheromones used with TUTASAN WATERTRAPS attract and capture many male adults. This slows down the growth of the population. Deploy 20 to 40 traps per hectare inside the greenhouse, depending on pest pressure. Change pheromone dispensers every four to six weeks.  

d. Chemical corrections

Since caterpillars are typically the damaging stage, mass trapping may generally not be sufficient for total pest control depending on the time of intervention and pest pressure. Chemical interventions may thus come in handy to keep the pest below economic threshold. It is critical to proceed with caution when applying chemical pesticides especially if you are already working with a biological pest control program.  

Contact your local Koppert consultant to evaluate the effect of the chemical interventions and their effects on natural enemy populations. Better still, refer to the Koppert chemical compatibility list provided by your local consultant or refer to our side effects tool on our website.