Female olive fly.

<p>Female olive fly.</p

Daily pattern on male sexual siganlling.

<p>Daily rhythm of sexual signalling on adult day 6 of sterilized male <i>C</i>. <i>capitata</i> of the Vienna 8 GSS in four different exposure compounds (orange oil, limonene, mixture of 5 pure compounds and control) on yeast hydrolyzate & sugar (YS, left column) and sugar only (S, right column). Values on y axis indicate the mean number (±SE) of males signalling per cage. Ten cages were considered containing 10 males each.</p

Effects of exposure to citrus compounds on male sexual signaling.

<p>Overall levels of sexual signalling activity (mean number of males signalling through the ages of 6 to 10 days old and 16 days old) of Vienna 8 GSS sterilized males medflies that were exposed during day 4 and 5 of adult life to orange essential oil, limonene, and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene 1:1:1:1:1 ratio) or left unexposed (control) fed on (A) yeast hydrolyzate & sugar (YS) and (B) sugar only (S). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. Values on y-axis are mean numbers (±SE) of males signalling per cage per hour observation. Means followed by the same lowercase letter are not significantly different (P>0.05, Tukey’s HSD test).</p

Repeated measures ANOVA on the effect of exposure compound (orange oil, limonene, mixture of 5 pure compounds and control), food (yeast hydrolyzate and sugar and sugar only) and age (repeated factor) on sexual signalling on sterilized (Vienna 8 GSS), <i>Ceratitis capitata</i> males.

<p>Males from adult age day 6 to adult day 10 and adult day 16 were considered in the analysis.</p

Age specific ratio on male sexual signaling.

<p>Ratio between signalling rates of Vienna 8 GSS sterilized male medflies fed on either yeast hydrolyzate & sugar (YS) or sugar only (S) in relation to age. Males had been exposed during day 4 and 5 of adult life to orange essential oil, limonene, and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene, 1:1:1:1:1 ratio) or left unexposed (control). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. The ratio was estimated considering the average calling for each day of the observation during 07:00 to 20:45 for protein and sugar treatments.</p

Diet specific effects on male sexual signaling.

<p>Effect of yeast hydrolyzate and sugar (YS) and sugar only (S) on the overall levels of sexual signalling activity (mean daily activity through the ages of 6 to 10 days old and 16 days old) of Vienna 8 GSS sterilized male medflies, that were exposed during day 4 and 5 of adult life to orange essential oil, limonene and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene, 1:1:1:1:1 ratio) or left unexposed (control). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. Values on y-axis are mean numbers (±SE) of males signalling per cage per hour observation (** P<0.001, *P<0.01, <i>t</i>-test YS vs S in each treatment).</p

Longevity parameters of adult medflies that were exposed and non-exposed to the aroma of citrus oil and held in diet restriction (sugar fed only) and in full diet (yeast and sugar fed) food conditions.

<p>Within diet regime, numbers followed by different letters are significantly different (pairwise comparisons log-rank test, P < 0.05).</p

Male longevity.

<p>Age-specific survival patterns of sterilized male <i>C</i>.<i>capitata</i> of the Vienna 8 GSS that were either exposed (solid line) or non-exposed (dashed line) to citrus oil: (A) males in full diet (yeast-sugar fed) conditions, (B) male in diet restriction (sugar only fed), (Log-rank pairwise tests reveal significant differences between exposed and non-exposed males fed in sugar, <i>P</i> < 0.05).</p

Repeated measures ANOVA on the effect of exposure compound (orange oil, limonene, mixture of 5 pure compounds and control), food (yeast hydrolyzate and sugar and sugar only) and time of day (repeated factor) on daily rhythms of sexual signalling on sterilized (Vienna 8 GSS) <i>C</i>. <i>capitata</i> males.

<p>Times of the day between 07:00 and 20:45 hours of adult day 6 were considered in the analysis.</p

Towards improving sterile insect technique: Exposure to orange oil compounds increases sexual signalling and longevity in <i>Ceratitis capitata</i> males of the Vienna 8 GSS

<div><p>The Mediterranean fruit fly (medfly), <i>Ceratitis capitata</i>, is a notorious insect pest causing huge economic losses worldwide. The sterile insect technique (SIT) is widely used for its control. Using sexually mature sterilized males of the Vienna 8 (tsl) strain in the laboratory, we explored whether exposure of males to citrus compounds (separately or in a mixture) affects their sexual behaviour and if nutritional conditions and age modulate those effects. Exposed males exhibited increased sexual signalling compared to unexposed ones, particularly when fed a rich adult diet. Interestingly, and for the first time reported in medfly, exposure of Vienna 8 males to a mixture of citrus compounds increases longevity under poor adult diet conditions. We discuss the possible associated mechanisms and provide some practical implications of our results towards improving the effectiveness of SIT.</p></div