Budworms on tomato plants

Budworms, also known as tobacco budworms, are caterpillars of the Helicoverpa moth family (previously called Heliothis moths). These destructive pests also attack stressed plants of sweet corn, tomatoes, a range of other fruits and vegetable plants and ornamentals.

An adult budworm.

Larva of budworm.



The moths lay their eggs at night on young foliage close to fruits or flower buds and the young caterpillars feed on the foliage first before moving into buds or developing fruits. After several weeks of feeding, the caterpillars burrow into the topsoil beneath the plant and pupate until rain that produces a burst of new plant growth will signal an opportune time for adult moths to emerge from pupa cases and lay eggs. If you netted plants after the first moth attack, they won’t be protected from further attacks because the pupating moths will be inside the netting.

 

Damage on the crop

 

Larvae bore into buds and blossoms (the basis for the common name of this insect), and sometimes the tender terminal foliar growth, leaf petioles, and stalks. In the absence of reproductive tissue, larvae feed readily on foliar tissue. It is infested tobacco with both tobacco budworm and corn earworm, and observed very similar patterns and levels of injury by these closely related species. Entry of larvae into fruit increases frequency of plant disease. Research in southern Arkansas tomato fields indicated that although tobacco budworm was present from May through July, they were not nearly as abundant or damaging as corn earworm.

Natural Remedy

Numerous general predators have been observed to feed upon budworm. Among the most common are Polistes spp. wasps (Hymenoptera: Vespidae); bigeye bug, Geocoris punctipes (Hemiptera: Lygaeidae); damsel bugs, Nabis spp. (Hemiptera: Nabidae); minute pirate bugs, Orius spp. (Hemiptera: Anthocoridae), and spiders. You can buy anyone of these and spread on plants which are infected by budworm.

Management

Several management methods can be used to flee budworms from your tomato plants. Some of them are as follows.

Sampling
Large cone-shaped wire traps baited with sex pheromone lures are commonly used to capture tobacco budworm moths. Smaller bucket traps can capture these moths, but they are not very efficient.

Insecticides
Foliar insecticides are commonly used in crops where tobacco budworm damage is likely to occur. However, destruction of beneficial organisms often results, and this is thought to exacerbate budworm damage. Also, resistance to insecticides is widespread, particularly in crops where pyrethroid use is frequent. Larvae will also consume bait formulated from cornmeal and insecticide.

Cultural techniques
Early season destruction of weeds with herbicide or mowing, or destruction of larvae on the weeds by treatment with insecticides, can reduce tobacco budworm population size later in the year.

Biological Control
The microbial insecticide Bacillus thuringiensis is effective against budworm. Heliothis nuclear polyhedrosis virus has been used effectively to suppress tobacco budworm on field crops and on early season weed hosts. Tobacco budworm also is susceptible to nuclear polyhedrosis virus from alfalfa looper, Autographa californica. Release of Trichogramma egg parasitoids has been shown to be beneficial in some vegetable crops.

Host plant resistance
Although there is little evidence for natural resistance to tobacco budworm among many crops, cotton is being genetically engineered to express resistance. Enhanced resistance to larval survival by cotton should result in lower insect pressure on nearby vegetable crops.