The squash vine borer is a serious pest of vine crops, commonly attacking squash, pumpkins, and gourds. Cucumbers, butternuts, and melons are less frequently affected.
These insect pests usually occur in low numbers although their presence is usually not noticed until after the damage is done.
The larval stage burrows in the plant stem or crown, disrupting the transport of water and nutrients, which results in wilting of affected plants or stems
In home gardens, the entire crops may be lost in cases of high borer populations.
DESCRIPTION
The eggs are about the size of a pencil point, brown and flattened.
Larvae have a brown head, white body and are rarely found outside of the vine. They have 8 pairs of appendages from their body. The first 3 pairs are true legs, the second 5 pair are prolegs or extensions from the body wall. Each proleg has 2 rows of curved spines.
Pupae are about 2 cm long, silk lined, black and usually found in the soil.
The adult borer may be mistaken for a wasp. It is about 0.5 inch long with an orange abdomen with black dots. The front wings are a metallic green and the rear wings are transparent with black or brown margins and veins. Wingspan is approximately 2.5 – 4 cm. The body is orange and black, often in a ringed pattern surrounding the abdomen.
LIFE CYCLE
Squash vine borers overwinter as mature larvae or pupae in the soil
Eggs are laid singly or in small groups at the base of susceptible plants. Approximately 7-10days after they are laid, the eggs hatch and the resulting larvae bore into stems to feed.
The larvae feed through the center of the stems, blocking the flow of water to the rest of the plant. They feed for 4-6 weeks, by continuing to tunnel through the stem of the plant, and when they are ready to pupate they burrow into the soil and spin a cocoon.
Squash vine borer adults emerge from cocoons in the ground and are good fliers. These moths are unusual because they fly during the day while nearly all other moths fly at night.
DAMAGE
The squash vine borer injures plants by tunneling through their stem/vines, which interferes with the nutrient transfer in the plant. The borer feeding weakens plants providing the opportunity for secondary infection.
Often, the first symptom of a borer attack is wilting of affected plants, which mostly occurs in the strong sun at first, but if the problem is left unchecked, the plants eventually collapse and die.
A closer observation of a wilting plant often shows holes near the base of the plant filled with moist greenish or orange sawdust-like material called frass, which protrudes from any damaged areas.
Over time, the base of the plant may become mushy or rot away altogether.
If vine senescence occurs early, the borer may tunnel into the fruit.
Several borer larvae may attack a single plant.
MANAGEMENT
Chemical control
This involves the use of insecticides, which works effectively when applied before the
Larvae bore into the stems. Therefore timely chemical spray and a regular spray regime is highly recommended.
The following insecticides are recommended against squash vine borers;
- PROFILE 440EC 30ml/20l
- KINGCODE ELITE 50EC 10ml/20l
- SINOPHATE 750SP 20g/20l
- PRESENTO 200SP 5g/20l
- PENTAGON 50EC 10ml/20l
- LEXUS 247SC 8ml/20l
- BACIGUARD 16000WDG 15g/20l
- LEGACY 50EC 15ml/20l
- TRUMPET 200SC 25ml/20l
While spraying the insecticides, it is advisable to mix it with INTEGRA 3ml/20l, which is a sticker, spreader and penetrant that improves the efficacy of the chemical.
Several insecticides should be alternated in a crop’s season in order to prevent the pest from gaining resistance over either of the chemicals.
Non-chemical methods
They include the following;
- Plant resistant cultivars
- Practicing rotations and intercropping to reduce pest population
- Maintenance of field sanitation/hygiene
- Proper weed control in order to ensure the insect cannot hide in the weeds
- Destroying the attacked crops
- Use of natural enemies to reduce the population.
