Ceratitis capitata Evaluation

Delgado, Soledad, Calvo, María Victoria, Duarte, Felicia, Borges, Alejandra & Scatoni, Iris Beatriz, 2022, Food attractants for mass trapping of fruit flies (Diptera: Tephritidae) and its selectivity for beneficial arthropods, Florida Entomologist 105 (3), pp. 185-193 : 187-189

Ceratitis capitata Evaluation

Dixieland peach field trial. During the first season of evaluation (Nov 2016 – Feb 2017), 694 tephritids were captured in the 12 test wk, with 522 females and 172 males. Ceratitis capitata represented 94% of the captures and A. fraterculus only 6%. Hydrolyzed protein (35%, 6.7 females per trap per d), liquid trimethylamine (24%, 4.9 females per trap per d), and trimethylamine diffuser card (23%, 4.4 females per trap per d) were the more efficient attractants and together captured 82% of total C. capitata captured ( Fig. 1A ). Commercial harvest was on the ninth wk of evaluation. None of the attractants showed significant differences in their efficiency during the pre-harvest period.

In the second season of evaluation (Dec 2017 – Apr 2018), a total of 5,634 tephritids were captured in the 16 test wk, with 3,742 females and 1,892 males. Ceratitis capitata captures represented 99.7% of the total, while only 0.3% were A. fraterculus . In this season, commercial harvest was on the sixth wk. Trimethylamine diffuser card (29%, 22.2 females per trap per d), hydrolyzed protein (25%, 20 females per trap per d), ammonium acetate + putrescine (19%, 14.2 females per trap per d), and liquid trimethylamine (19%, 13.9 females per trap per d) were the more efficient attractants for C. capitata and together captured 92% of total tephritids ( Fig. 1B ). Hydrolyzed protein also was the best attractant in the pre-harvest period. In both seasons of evaluation all attractants captured more C. capitata females in the post-harvest period than in the pre-harvest period, and liquid trimethylamine captured C. capitata before other attractants.

Fuji Kiku apple field trial. During the first season of evaluation (Feb 2017 – May 2017), a total of 1,143 C. capitata were captured in the 13 test wk, with 919 females and 224 males. Hydrolyzed protein (30%, 6.4 females per trap per d), ammonium acetate + putrescine (24%, 5 females per trap per d), trimethylamine diffuser card (18%, 3.9 females per trap per d), and liquid trimethylamine (17%, 3.5 females per trap per d) were the more efficient attractants and together captured 89% of C. capitata ( Fig. 1C ). Commercial harvest was on the sixth wk of trial. None of the attractants showed significant differences in their efficiency during the pre-harvest period.

In the second season of evaluation (Feb 2018 – May 2018), a total of 1,152 C. capitata were captured in the 13 test wk, with 891 females and 261 males. Hydrolyzed protein (39%, 11.6 females per trap per d), liquid trimethylamine (28%, 6 females per trap per d), and trimethylamine diffuser card (19%, 6.3 females per trap per d) were the more efficient attractants and together captured 86% of the C. capitata ( Fig. 1D ). In this season, commercial harvest was on the tenth wk of trial. In both seasons of evaluation, all attractants captured more tephritids in the post-harvest period than in the pre-harvest period. Hydrolyzed protein and liquid trimethylamine also were the more efficient attractants in the pre-harvest period. Liquid trimethylamine was able to detect the presence of C. capitata before other attractants on both seasons.

Satsuma mandarin field trial. In the case of Satsuma Okitsu mandarin, during the first season of evaluation (Feb 2017 – May 2017) only 169 C. capitata were captured in the 12 test wks,with 133 females and 36 males. Commercial harvest was on the sixth wk of trial. No significant differences were observed among the attractants ( Fig. 1E ). The 2017 season was char- acterized by the low prevalence of C. capitata in the study area.

In the second season of evaluation (Feb 2018 – May 2018) on Satsuma Owari mandarin, only 211 C. capitata were captured in the 12 test wk, with 170 females and 41 males. Commercial harvest was on the sixth wk of trial. Liquid trimethylamine (29%, 0.7 females per trap per d), hydrolyzed protein (27%, 1.5 females per trap per d), trimethylamine diffuser card (16%, 0.7 females per trap per d), and ammonium acetate + putrescine (15%, 0.9 females per trap per d) were the more efficient attractants and together captured 92% of the C. capitata ( Fig. 1F ). These attractants also were more efficient for the pre-harvest period. In all field trials, all treatments were able to capture significantly more females than males. Anastrepha fraterculus Evaluation

The presence of A. fraterculus was detected only in the Dixieland peach field trial but in a very low density, with a C. capitata / A. fraterculus ratio of 15: 1 in the 2017 season and 304: 1 in the 2018 season. However, an average infestation of 0.45 pupae of A. fraterculus per kilogram of fruit sampled was observed in season 2017. This was the only field trial and season where fruit infestation was detected.

In the 2017 season, hydrolyzed protein (58%, 0.51 females per trap per d), liquid trimethylamine (24%, 0.20 females per trap per d), Torula yeast (9%, 0.08 females per trap per d), and ammonium acetate + putrescine (9%, 0.08 females per trap per d) captured A. fraterculus females with no significant differences between them. In the 2018 season, hydrolyzed protein (60%, 0.15 females per trap per d), liquid trimethylamine (16%, 0.04 females per trap per d), Torula yeast (16%, 0.04 females per trap per d), and trimethylamine diffuser card (8%, 0.02 females per trap per d) captured A. fraterculus females with no significant differences between them.

PROPORTION OF GRAVID AND NON-GRAVID FEMALES CAPTURED

In the 2017 season, the 1,505 C. capitata females captured in the different treatments and fruit crops were dissected. Non-gravid females represented 77% of the females captured, considering the pre- and post-harvest period ( Fig. 2 ). In the 2018 season, 1,947 C. capitata females were captured, with 75% non-gravid ( Fig 3 ).

For the case of A. fraterculus in the Dixieland peach trial, only hydrolyzed protein was able to capture significantly more non-gravid females (e.g., 7 non-gravid vs. 1 gravid in the second season). This was due to the lack of captures of this species (33 females in the first season and 12 females in the second season).

All treatments evaluated captured non-gravid females. Hydrolyzed protein and liquid trimethylamine captured significantly more non-gravid females during the pre- and post-harvest period in all field trials in both seasons. Trimethylamine diffuser card, ammonium acetate + putrescine, and Torula yeast captured more non-gravid females, mostly in the post-harvest period of the Dixieland peach and Fuji Kiku apple trials ( Figs.2 & 3 ).

SELECTIVITY OF ATTRACTANTS REGARDING BENEFICIAL ARTHROPODS

Captures of beneficial arthropods were not significantly different among the evaluated food attractants, despite the differences they may present in terms of their efficiency of capturing tephritids ( Fig. 4 ). The more efficient attractants were not necessarily the more selective regarding non-target insects (beneficial arthropods + other non-target insects). The least selective attractant was sugarcane molasses, in which the fraction of beneficial arthropods caught reached 6.7% of total captures in Satsuma Owari mandarin (2018 season) ( Fig. 4E ).

In most treatments and field trials, non-target insects are the great- est proportion of captured arthropods. Diptera , such as Muscidae and Drosophilidae , dominated captures in all treatments. Only in the Dixieland peach field trial during the 2018 season were C. capitata captures significantly larger than non-target insect captures for 3 attractants: trimethylamine diffuser card, liquid trimethylamine, and ammonium acetate + putrescine ( Fig. 4B ). In this case, trimethylamine diffuser card was the most specific attractant, where tephritids accounted for 74.5% of the captures, followed by liquid trimethylamine (71.5%), ammonium acetate + putrescine (59.2%), hydrolyzed protein (45.3%), and Torula yeast (13.8%).

Figures

Fig. 1. Cumulative Ceratitis capitata captures expressed as females per trap per d index for the pre-harvest (light gray) and post-harvest (dark gray) periods are shown, for the 3 field trials and the 2 seasons of evaluation. Different letters indicate significant differences between treatments in the cumulative captures of females for the total trial period.

Fig. 2. Proportion of gravid (dark grey) and non-gravid (light grey) females of Ceratitis capitata lured to the different treatments on pre- and post-harvest period during the 2017 season (NS = no significant differences, * = P ≤ 0.05). (A–B) Dixieland peach; (C–D) Fuji Kiku apple; (E–F) Satsuma mandarin. Treatments with no captures are not presented.

Fig. 3. Proportion of gravid (dark grey) and non-gravid (light grey) females of Ceratitis capitata lured to the different treatments on pre- and post-harvest period during the 2018 season (NS = no significant differences, * = P ≤ 0.05). (A–B) Dixieland peach; (C–D) Fuji Kiku apple; (E–F) Satsuma mandarin. Treatments with no captures are not presented.

Fig. 4. Proportion of tephritids (dark grey), beneficial arthropods (white), and other non-target insects (light grey) captured by the different treatments in the 2017 and 2018 seasons.