High Summer Temperatures Affect the Survival and Reproduction of Olive Fruit Fly (Diptera: Tephritidae)

High temperature affects olive fruit fly populations in California's Central Valley

“…When subjected to 65°F (night) and 100°F (day), no eggs hatched after 10 days exposure and all died. The overall finding was that egg (F 3,57 = 2472, P < 0.001) and first-instar (F 3,57 = 2472, P < 0.001) mortality increased as exposure time increased (Wang et al 2009a).Later field studies showed that maximum daily temperatures in olive trees in the Central Valley (Parlier) varied depending on whether measurements were taken within the canopy interior or the east or west perimeter. Mean temperatures recorded on the west side of the tree canopy in August 2007 were 108°F (and over 104°F for 26 days) compared to 101°F (and over 104°F for 13 days) on the east side, and 96°F (and never over 104°F) within the canopy interior (F 2,90 = 52.7, P < 0.001).…”

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An adult female olive fruit fl y deposits an egg into olive fruit.As temperatures surpass 84°F, adult fl ies become increasingly agitated and egg laying is halted, and above 95°F they are motionless.

Marshall W. Johnson30 CALIFORNIA AGRICULTURE • VOLUME 65, NUMBER 1 suggest that adults seek and remain near moisture sources as temperatures approach and surpass 95°F.Reduced adult fly activity can result in lower trap counts in the field while maximum daily temperatures remain around 95°F to 99°F and the flies have access to adequate water and carbohydrate sources (Wang et al 2009a). However, as the frequency at which daily maximum temperatures equal or surpass 100°F increases, greater numbers of adults will die due to heat stress, especially when they cannot access adequate quantities of water and food (Wang et al 2009a, b) (fig.

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“…During periods of high maximum daily temperatures (3 consecutive days at 100°F or above in July and August) (Lynn-Patterson 2006), mated adult females may lay their eggs in developing olives prior to morning temperatures reaching 95°F. No eggs are deposited during the night, even when temperatures are cool enough for normal activity (Avidov 1954;Wang et al 2009a). Eggs are deposited just beneath the fruit epidermis and may be exposed to high temperatures, depending on where an individual fruit is located on the tree (Wang et al 2009a).…”

“…No eggs are deposited during the night, even when temperatures are cool enough for normal activity (Avidov 1954;Wang et al 2009a). Eggs are deposited just beneath the fruit epidermis and may be exposed to high temperatures, depending on where an individual fruit is located on the tree (Wang et al 2009a).Laboratory studies showed that adult females held under different diurnal temperature regimes (65°F at night and 75°F, 95°F or 100°F during the day) laid similar numbers of eggs when the temperature was 65°F and the experimental chamber was illuminated (F 2,55 = 0.2, Even after eggs are deposited within olive fruit, they are still susceptible to the high temperatures common in Central Valley orchards. Eggs within fruit held at 65°F (night) and 75°F (day) developed into first-instar larvae after 6 days (Wang et al 2009a).…”

“…Eggs are deposited just beneath the fruit epidermis and may be exposed to high temperatures, depending on where an individual fruit is located on the tree (Wang et al 2009a).…”