Pezothrips kellyanus, (Bagnall) (Bagnall, 1916)

Planes, Laura, Catalán, Jose, Jaques, Josep A., Urbaneja, Alberto & Tena, Alejandro, 2015, Pezothrips kellyanus (Thysanoptera: Thripidae) nymphs on orange fruit: importance of the second generation for its management, Florida Entomologist 98 (3), pp. 848-848 : 848-

EFFICACY AGAINST P. KELLYANUS ADULTS

Of the 2,275 adult thrips collected with the vacuum device in Tavernes, 1,951 (85.8%) were P. kellyanus . The number of P. kellyanus adults captured 1 d before the treatments was similar among treatments (F 3,15 = 1.87; P = 0.19) ( Fig. 1 ). However, 2 d afer the treatments, the number of adults increased and became significantly greater in control plots and in plots treated with spirotetramat (F 3,15 = 8.59; P = 0.002) than in the other treatments. The efficacy of spinosad (89.4 ± 4.1 %, mean ± SE) and chlorpyrifos (86.5 ± 4.4 %) was high, and there were no significant differences between them (F 1, 7 = 0.22; P = 0.65). Seven days afer the treatments, the numbers of captured adults remained significantly smaller than in the control only in the plots treated with spinosad (F 3,15 = 5.33; P = 0.015). Fourteen days afer the treatment,the numbers of captured adults decreased in the control plots and were the same in all treated plots (F 3,15 = 0.68; P = 0.58).

DAMAGE

In Alzira, the percentage of severely damaged fruits was significantly lower in the treated trees than in control trees ( Fig. 2A ), and it was significantly lower in trees treated with chlorpyrifos and spinosad than with spirotetramat (F 3,34 = 13.85; P <0.001). The efficacy of chlorpyrifos and spinosad was significantly higher than that of spirotetramat (F 2,25 = 5.53; P = 0.01). The percentage of slightly damaged fruits was significantly lower for the trees treated with chlorpyrifos and spinosad than control and spirotetramat trees (F 3, 34 = 5.72; P = 0.003). There were no significant differences between the efficacy of chlorpyrifos and spinosad (F 1,16 = 1.81; P = 0.22).

In Tavernes, however, the percentages of slightly and severely damaged fruits were high, and there were no significant differences among the 3 treatments and the control (slightly damaged: F 3,15 = 0.33; P = 0.09; severely damaged: F 3,15 = 0.53; P = 0.67) ( Fig. 2B ).

SIDE EFFECTS

The numbers of phytoseiids per leaf were similar in all plots the day before treatments in Tavernes (Table 3). Their densities did not differ significantly the following days. However, the accumulated phytoseiidday values, used as an overall summary statistic, were significantly lower in the plots treated with spinosad and spirotetramat than in those untreated or treated with chlorpyrifos.

We captured and identified 1,740 natural enemies with the vacuum device ( Table 4 ). Hymenopteran parasitoids were the most abundant, in total 927 were collected, followed by neuropteran predators (286) and arachnid predators (241). In general, the total number of natural enemies captured was higher in untreated plots (control) than in the treated plots in the following days. There were no significant differences among treatments on day −1 (F 3,15 = 0.85; P = 0.49), day 14 (F 3,15 = 0.50; P = 0.69), and day 21 (F 3,15 = 0.85; P = 0.49) in the total number of natural enemies captured. However, the total numbers of natural enemies captured in the plots treated with spinosad and chlorpyrifos were significantly smaller than in those untreated on day 2 (F 3,15 = 6.27; P = 0.0084). Similarly, the total numbers of natural enemies captured in the plots treated with the 3 insecticides were significantly smaller than in those untreated on day 7 (F 3,15 = 10.71; P = 0.001). We could not determine the side effects of the insecticides on the main natural enemies of citrus, namely the hymenopteran parasitoids Aphytis melinus DeBach ( Aphelinidae ), Cales noacki Howard ( Aphelinidae ), Citrostichus phyllocnistoides (Narayanan) ( Eulophidae ), and Metaphycus spp. ( Encyrtidae ) and the predators of the family Coccinellidae , because of the small numbers of specimens of these species collected ( Table 4 ).

Figures

Fig. 1. Number of Pezothrips kellyanus adults collected with a vacuum device in a navel orchard located in Tavernes (mean ± SE). Trees were treated with chlorpyrifos, spinosad,or spirotetramat.

Fig. 2. Percentage (mean ± SE) of fruits slightly and severely damaged by Pezothrips kellyanus nymphs in every insecticide plot in orchards of Alzira (A) and Tavernes (B). Trees were treated with chlorpyrifos, spinosad, or spirotetramat. Different letters indicate significant differences (P <0.05) between treatments (1-way ANOVA followed by Tukey post hoc tests).