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Bug pests in vegetable crops

Bugs – an overview:

This page provides an overview of bug pests in vegetable crops. The related tools listed at the end of the page provide detailed information about their identification, damage and management. It is important to be able to identify insect pests such as bugs, and to have unknown species expertly identified so that they can be appropriately managed.

Bugs are sap-sucking pests, and damage to susceptible plants is similar to that caused by aphids. Both immatures (nymphs) and adult bugs can cause damage to a wide range of vegetable crops through using their needle-like mouthparts to pierce the plant and suck up the cell contents. Bugs can move into crops from nearby weeds and may be found on all plant parts.

Bug species, hosts, and damage:

Bug species

Description

Host vegetable crops

Primary damage
Rutherglen bug (Nysius vinitor) Adult bugs are about 5 mm long, with narrow grey-brown-black bodies. Their wings form a cross-like pattern on their back. Found in a range of crops, mainly lettuce. Cause plants to wilt when present in large numbers and contamination problems.
 Green vegetable bug (Nezara viridula) Adults have a bright green chisel-shaped body. Beans; sweet corn; tomato; potato; cucurbits  Feeding through piercing and sucking sap causes water soaked lesions to develop and some malformation in growth around the affected area. Reduced vigour, premature flower drop, seed damage, and distorted development may be observed. In beans, pods may abort.
Mirid bugs – Green mirid (Creontiades dilutus) Adults have slender, green bodies with light brown markings on translucent wings. Very active. Cucurbits Suck sap and release enzymes that destroy surrounding plant cells, causing parts of the plant to wilt and die.
 Mealybugs Wingless insects, usually less than 6 mm long, with an oval body like a slater and covered with white waxy powder or threads. Prefer plants with high nitrogen content. Greenhouse crops. Cause extensive damage to roots, stems, and leaves.

Pest management:

Bugs:

  • Cultural control: Control weeds in and around the crop.
  • Chemical control: Insecticides may be required if numbers of Rutherglen bug become too high. Refer to the APVMA website or a commercial chemical database for pesticide options.
  • Biological control: Green vegetable bug numbers are often kept under control by small wasp parasitoids. Green vegetable bug eggs are frequently controlled by a tiny introduced wasp Trissolcus basalis – green vegetable bug egg parasite. Other natural predators of this pest include ants, spiders, and predatory bugs.

Mealybugs:

  • The most effective is biological control – important predators of mealybugs include lacewing larvae and ladybirds. Both scales and mealybugs are parasitised by tiny wasps that lay eggs in the body of the host insect.
  • Chemical controls include oil sprays that control scale insects and mealybugs by smothering them. Eggs that are under the adult scale insects will not be killed. Various contact and systemic chemicals are available to kill mealybugs that are feeding. Once the pest has stopped feeding, it is too late to control it.

Source of information and related tools: