Abstract:
Frugivorous insects use visual, chemical and tactile cues to find a suitable host for oviposition. However, these cues can vary greatly among fruit cultivars and condition, changing their susceptibility to fruit fly oviposition. The aims of this study were to (1) determine the effects of ripeness stage and damage on oviposition propensity by sexually mature, mated female oriental fruit flies, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), on five citrus types (species and cultivars) under choice and no-choice conditions and (2) describe the oviposition behaviour of B. dorsalis on ripe fruit of the same five citrus types that were either damaged or undamaged under no-choice conditions. All tests were conducted in the laboratory. The citrus types tested were Citrus sinensis (L.) Osbeck cv Delta Valencia orange, Citrus sinensis (L.) Osbeck cv Glen Ora Late navel orange, Citrus limon (L) (Burm.f.) cv Eureka lemon, Citrus paradisi (Macfad.) cv Star Ruby grapefruit and Citrus reticulata (Blanco) cv Nadorcott mandarin. Peel physical properties and essential oil composition were determined for each citrus type and stage. Oviposition propensity of B. dorsalis was significantly greater on damaged citrus but was not correlated with fruit diameter, peel thickness, oil gland density or oil gland size. A total of 45 aromatic compounds were found to be significant between the five cultivars investigated, and 6 of 11 compounds were significantly associated with over-ripe fruits. Bactrocera dorsalis spent a significantly greater proportion of time ovipositing in damaged citrus and showed higher aggression when oviposition occurred in undamaged citrus. These results suggest that the removal of damaged and fallen fruit is important for controlling this pest in citrus orchards.
Description:
SUPPORTING INFORMATION : TABLE S1. Ethogram of sexually mature, mated female B. dorsalis displayed on five ripe citrus types and a positive control under undamaged and damaged conditions.
TABLE S2. Significant indicator compounds per fruit type. Significance level recorded as p < 0.05.
TABLE S3. Significant indicator compounds by varying fruit ripeness. Significance level recorded as p < 0.05.
TABLE S4. Number of replicates (from n = 10) with stings (eggs) detected in citrus types at four stages of ripeness after exposure to five gravid female B. dorsalis under no-choice conditions (undamaged or damaged) in a laboratory. Ripe Golden Delicious apples were used as a control.
TABLE S5. Number of replicates (from n = 10) with stings (eggs) detected in citrus types at four stages of ripeness after exposure to five gravid female B. dorsalis under choice conditions (undamaged or damaged) in a laboratory. Ripe Golden Delicious apples were used as a control.
FIGURE S1. First order Markovian analyses showing the probability of transition from one behaviour to another by gravid female B. dorsalis on (a) damaged and (b) undamaged apple (all types pooled). Transitions with P ≥ 0.10 are indicated by solid lines, and those with 0.09 ≥ P ≥ 0.03 are indicated with dashed lines. Values in parentheses indicate frequencies of each behaviour observed.
