Why do guava fruit flies, Anastrepha striata (Tephritidae), avoid the upper canopy of host trees?

Abstract

The within‐tree distribution of the guava fruit fly, Anastrepha striata in sour guava, Psidium friedrichsthalianum and common guava, P. guajava in the seasonal highlands and non‐seasonal lowlands of Costa Rica, was examined in relation to host fruit distribution, temperature, and ambient light levels. Larvae and adult flies were significantly more abundant in the middle and lower parts of trees than in the upper canopy layer where temperatures inside sun‐exposed, potential host fruits reached lethal levels for eggs and larvae of A. striata. The number of adult flies was also significantly greater in relatively compact foliage than in fairly open foliage of host trees. The results suggest that the foliage structure of host trees, through its influences on the temperature inside host fruits, is determining the within‐tree distribution of Anastrepha fruit flies.

Keywords:

• Fruit flies
• Anastrepha
• A. striata
• vertical distribution
• abiotic factors
• guava
• Psidium spp.
• Costa Rica