Achaearanea trapezoidalis

Systematic position. Achaearanea trapezoidalis belongs to the order Araneae and the family Theridiidae (cobweb spiders). While these spiders primarily act as predators, in certain agricultural environments, their habit of spinning dense webs can interfere with crop management and plant health, classifying them as pests in specific greenhouse scenarios.

Affected crops and damage. This species primarily affects ornamental plants, berries, and various vegetable crops grown under greenhouse conditions. The damage is primarily physical; the dense webbing covers leaves and buds, hindering light absorption and potentially leading to the stunting of young seedlings if left unmanaged.

Biology and life cycle. The life cycle consists of egg, nymph, and adult stages. Females produce characteristic pear-shaped egg sacs, which are anchored securely within the web structure. The rate of development is highly dependent on ambient temperature and humidity, with warm, sheltered environments promoting rapid population growth.

Damage characteristics. The presence of these spiders is easily identified by the vast, unorganized web networks stretching between plant parts. This webbing traps dust and debris, which creates a dirty appearance and may foster secondary infections such as molds, negatively impacting both the health and aesthetic quality of the plants.

Protection measures. Integrated pest management involves regular scouting and physical removal of the webbing and egg sacs. Improving greenhouse ventilation to reduce stagnant, humid air is an effective preventative measure. If populations become high, chemical control using targeted acaricides may be employed, provided they are approved for the specific crop variety.