Temporal overlap and co-occurrence in a guild of sub-tropical tephritid fruit flies

Studies of community assembly have emphasized snapshot comparisons of spatially replicated samples from natural assemblages. Agro-ecosystems are characterized by relatively little habitat heterogeneity and no dispersal barriers for actively flying insects. Therefore, dynamic patterns of species segregation and aggregation are more likely to reflect the direct or indirect effects of species interactions. We studied the temporal organization of a guild of 21 congeneric species of Anastrepha that colonized fruit orchards in Monte Alegre do Sul, São Paulo, Brazil. This assemblage also included the introduced Mediterranean fruit fly Ceratitis capitata. One hundred six consecutive weekly censuses (11 Jan 2002-16 Jan 2004) of flies in guava, loquat, and peach orchards revealed a pattern of minimum abundance during the coldest months of each year (June and July) and a maximum abundance during periods of flowering and fruit ripening. Overall, phenological overlap was greater than expected by chance. However, conditioned on the pattern of seasonal abundances, temporal occurrence and abundance matrices exhibited patterns of significant species segregation and anti-nestedness. In each year, the 3 orchards contained a small number of species pairs that exhibited statistically significant temporal segregation or aggregation. Most aggregated and segregated pairs reflected seasonal shifts in species presences that were not related to variation in air temperature. Most of the significant pairwise associations involved C. capitata: 8 of the 11 segregated pairs and 2 of the 7 aggregated pairs. These results suggest that species interactions between introduced and native species can be an important determinant of species associations in agro-ecosystems

Toxic effects of neem seed cake on the larval-pupal (prepupal) stage of Mediterranean fruit fly (Diptera: Tephritidae)

Introduction. Traditionally the control of fruit flies is based on the use of pesticides, which increase production costs and have led to many environmental concerns. Our study aimed to evaluate the effect of neem cake on the larval and pupal stages of Ceratitis capitata. Materials and methods. Third instar larvae were transferred to plastic vials with neem cake in different proportions. The treatments consisted of vermiculite with neem cake in the concentrations: control (vermiculite only), then (10, 25, 50, 75 and 100)% of neem seed cake. The bioassay was completely randomized, with six treatments, ten replicates and ten third instar larvae per replicate. The results were statistically analyzed. Results. At concentrations of 75% or more of neem cake in vermiculite, practically no adult flies emerged. At 50%, more than 80% of the adults did not emerge and the pupal period was prolonged. The sex ratio of the adults was not affected after the contact of the pupae with the neem cake. The estimated lethal concentrations to kill 50% and 90% of the population were 30.6% and 51.6%, respectively. Conclusion. The neem seed cake has contact actions against the larval-pupal stage of C. capitata. Neem seed cake in the pupation substrate can cause high mortality when its concentration is 50% or more, and it prolongs the delay of the pupal period of C. capitata

Analysis of average air temperatures and Julian calendar dates (= season) for time periods of species presences and absences in statistically significant species aggregations and segregations (see Table 4).

<p><b>Legend</b>:</p><p>Temp. Season</p><p>↔ = N.S. S.</p><p>Δ = S. N.S.</p><p>\ = N.S. N.S.</p><p>□ = Species pair association N.S.</p><p>S. = Significant</p><p>N.S. = No significant</p><p>Significant results indicate a pair of species in which aggregation or segregation was associated with non-random patterns of air temperature or seasonality (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132124#pone.0132124.g001" target="_blank">Fig 1</a>). ↔ = significant seasonal difference, no temperature difference; Δ = significant temperature difference, no seasonal difference; \ = significant species aggregation or segregation without associated differences in air temperature or seasonality; white = segregation or aggregation not statistically significant.</p><p>Analysis of average air temperatures and Julian calendar dates (= season) for time periods of species presences and absences in statistically significant species aggregations and segregations (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132124#pone.0132124.t004" target="_blank">Table 4</a>).</p

Observed and expected temporal niche overlap (Pianka’s index) and the one-tailed <i>p</i>-value based on 1000 randomizations for fruit fly assemblages sampled in three orchard types over two years.

<p>Observed and expected temporal niche overlap (Pianka’s index) and the one-tailed <i>p</i>-value based on 1000 randomizations for fruit fly assemblages sampled in three orchard types over two years.</p

Co-occurrence pattern based on presence-absence data of significantly segregated (red panels) and aggregated (green panels) pairs of tephritid fruit flies sampled in 3 orchards in the year 2003.

<p>Abbreviations as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132124#pone.0132124.g004" target="_blank">Fig 4</a>.</p

Significantly aggregated and segregated species detected in species co-occurrence analysis.

<p><b>Legend</b>:</p><p>- = Segregated</p><p>+ = Aggregated</p><p>□ = Pair not formed</p><p>- = significantly segregated species pair; + = significantly aggregated species pair; white = pair not occurring in a particular orchard/year. Pairwise analyses control for false discovery rates using the methods in Gotelli and Ulrich 2010 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132124#pone.0132124.ref037" target="_blank">37</a>].</p><p>Significantly aggregated and segregated species detected in species co-occurrence analysis.</p

Z-scores for null model analyses of presence-absence and abundance matrices of fruit flies in 3 orchards.

<p>The C-score index for presence-absence and the Checker index for abundance measure species segregation and aggregation. The NODF index for presence-absence and the Anodf index for abundance measure nestedness and anti-nestedness. Z scores larger than |2| indicate statistical significance. Positive values for the C-score and Checker indices indicate species segregation, whereas negative values for NODF and Anodf indicate anti-nestedness patterns. The fixed-fixed null model was used to randomize the presence-absence matrices, whereas the IT null model was used to randomize the abundance matrices. See Ulrich and Gotelli 2010 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132124#pone.0132124.ref031" target="_blank">31</a>] for details.</p><p>Z-scores for null model analyses of presence-absence and abundance matrices of fruit flies in 3 orchards.</p

Total abundance and species richness data of fruit flies in relation to time and fruit tree phenology for samples collected during two years (2002–2003) in an experimental station in Monte Alegre do Sul, state of São Paulo, Brazil.

<p>Total abundance and species richness data of fruit flies in relation to time and fruit tree phenology for samples collected during two years (2002–2003) in an experimental station in Monte Alegre do Sul, state of São Paulo, Brazil.</p

Fruit fly abundance, air temperature (°C), and sampling date for 3 fruit orchards sampled in Monte Alegre do Sul, São Paulo, Brazil in 2002 and 2003.

<p>The area of each circle is proportional to the total abundance of fruit flies collected in the sample.</p

Co-occurrence pattern based on presence-absence data of a significantly segregated species pair, <i>A</i>. <i>obliqua</i> ☓ <i>C</i>. <i>capitata</i>.

<p>The upper panel illustrates the co-occurrence patterns in temporal samples of <i>A</i>. <i>obliqua</i> (unfilled bars) and <i>C</i>. <i>capitata</i> (grey bars) collected in a loquat orchard in 2002. Box plots illustrate average air temperature (°C) and Julian collection date (plotted on a monthly scale) for samples that contained only <i>A</i>. <i>obliqua</i> or only <i>C</i>. <i>capitata</i> (temporal checkerboards). This species pair is segregated on the basis of seasonality, but not on the basis of temperature.</p