The tomato fruit borer, *Helicoverpa armigera*, is also known as *Heliothis armigera* (Hübner), and it belongs to the order Lepidoptera and the family Noctuidae. This pest affects a wide range of crops beyond just tomatoes, including eggplants, peppers, tobacco, and various Solanaceae plants, both cultivated and wild. Additionally, it damages kale, cabbage, cotton, wheat, beans, and many other crops. Particularly in open-field tomato cultivation, the threat from this pest demands close attention and effective control measures.
The damage caused by *H. armigera* varies depending on the plant part affected. First, it may feed on ripe fruits, creating holes that lead to rot after rain or irrigation. Second, young fruits are often eaten first, gradually becoming hollowed out. Third, when buds are attacked, their sepals may open prematurely and then turn yellow and fall off. Lastly, the larvae can infest young shoots, leaves, and tender stems, causing breakage. In large infestations, this can significantly reduce both yield and quality of tomatoes.
Morphologically, *H. armigera* is closely related to *H. assulta*. Both species are similar in size and color patterns, making them difficult to distinguish. However, key differences exist: the forewings of *H. armigera* are as long as the body, while those of *H. assulta* are shorter. The wing markings are less distinct and appear blurred. Larvae of *H. armigera* show variable coloration—white in the first instar, black in the second, yellow-green in the third, and reddish or purple-black in later stages. Their bodies are rougher compared to *H. assulta*, and the arrangement of lateral hairs on the thorax differs.
In terms of behavior, *H. armigera* has a higher number of generations per year—up to 6-7 in southern China—compared to *H. assulta*’s 5. It exhibits stronger phototaxis, especially to black light, but weaker chemotaxis. It is attracted to fresh poplar, willow, and skunk leaves, which is different from the tobacco budworm’s preference for flavor-based attraction. Moreover, *H. armigera* is more damaging to tomatoes than to peppers, unlike *H. assulta*.
For control, several methods can be applied:
1. **Egg Removal**: Since *H. armigera* lays eggs on the upper leaves or tops of tomato plants, pruning and burning infested shoots can effectively reduce egg populations. Using oxalic acid to attract eggs and potassium dihydrogen phosphate to repel them is another strategy. Small areas can benefit from these methods.
2. **Biological Control**: Spraying *Bacillus thuringiensis* (Bt) at a concentration of 16,000 IU/mg, diluted 1000–2000 times, during the peak egg-laying period can help manage larvae. Alternatively, using 2 billion polyhedrons per milliliter of nuclear polyhedrosis virus suspension at 50–60 ml per 667 square meters is also effective.
3. **Chemical Control**: During the egg-laying period and before the third larval stage, high-efficiency, low-toxicity pesticides should be used. Options include Kung Fu 2.5% EC diluted 2000–4000 times (18.75–37.5 ml per 667 sqm), Fast Enemy 5% EC at 3000 times (20 ml per 667 sqm), Cypermethrin 10% EC at 1000 times, Caesar 10.8% EC at 5000–7500 times, and Phoxim 50% emulsion at 1000 times.
4. **Insect Nets**: Covering crops with insect-proof nets has proven highly effective in controlling pests and reducing the spread of viral diseases. Studies show a significant reduction in tomato fruit borer infestation and a 70% decrease in virus strain occurrence. Nets can eliminate damage from multiple pests like diamondback moths, aphids, and whiteflies, and improve crop yields by up to four times. This method helps protect the environment and reduces pesticide use.
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