Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/11/2012
Publication Date: 10/1/2012
Citation: Yokoyama, V.Y. 2012. Mobility of olive fruit fly (Diptera: Tephritidae) late third instars and teneral adults in test arenas. Environmental Entomology. 41:1177-1183. Interpretive Summary: Olive fruit fly is the primary olive pest in California, the only state that produces canned olive fruit for the nation. Orchard control practices currently target the mature adults because of their ability to fly over great distances, while other stages of the pest have been ignored. In this study, the mobility of the late larval stage that leaves infested fruit to pupate in the soil, and the newly emerged adult that cannot yet fly was tested in different devices. Both stages were found to travel over long distances on the ground. Four mature larvae, placed end to end could crawl the length of a football field. Adults that did not yet develop wings could walk 42 feet in 22 minutes. When flight was restricted, young winged adults could walk down 25 foot pipes, and climb out of sand columns that were two feet high and weighed 41 pounds. Such feats were related to the need for control practices in olive orchards that may impede fruit infestations among trees by these lively stages. The work helps canned olive growers to develop olive fruit fly control strategies that would limit the spread of inner orchard pest infestations among new and establish olive trees.
Technical Abstract: The mobility of olive fruit fly, Bactrocera oleae (Rossi), late third instars before pupation, teneral adults before flight, and mature adults restricted from flight was studied under mulches in greenhouse cage tests, in horizontal pipes, vertical bottles and pipes filled with sand, and by observation on smooth laboratory surfaces. The percentage adults and females that escaped soil, fabric, and paper mulches over a soil or sand substrate ranged from 63-83, and 40-53%, respectively. The percentage adults and females that traveled through 1.52-6.10 m horizontal pipes of 1.5-2.0 cm inner diam ranged from 57-81, and 27-61%, respectively. The percentage adults that escaped through sand depths of 2.5-10.2, and 12.7-20.3 cm, ranged from 68-87, and 12-88%; and percentage escaped females ranged from 46-58, and 38-70%, respectively. In 15.4 cm inner diam pipes filled with different heights of sand, the highest percentage of adults that emerged from pupae, were found in the lower column from 0-20.3 cm, and ranged from 37-71%. Adults in the mid- to upper sand column ranged from 10-47%, and those escaping 20.3-50.8 cm high sand columns ranged from 6-21%. In column heights of 55.9 and 61 cm, pressures at the bottom caused by the weight of the sand above were 91.4 and 99.7 g per cm², respectively, and a mean of < 1 adult escaped to the top. The late third instars before pupation were found to travel continuously for 6.9 hrs over 23.9 m at a speed of 6.0 cm per min, when placed on a smooth surface, at 22.2°C. Teneral females and males that could not fly, made about 7 stops totaling 11-13 min, walked at a speed of 57-62 cm per min, and began a rest period of 83-84 min duration, at 85-89 min before flight. Males walked a distance of 13.1 m in 22 min, which was greater than females that walked for 9.6 m in 17 min, at 20-22°C and 35% RH. The mobility of the third instars and the teneral adults was discussed in relation to potential control techniques in olive orchards.