Behavior of Ants Escaping from a Single-Exit Room

<div><p>To study the rules of ant behavior and group-formation phenomena, we examined the behaviors of <i>Camponotus japonicus</i>, a species of large ant, in a range of situations. For these experiments, ants were placed inside a rectangular chamber with a single exit that also contained a filter paper soaked in citronella oil, a powerful repellent. The ants formed several groups as they moved toward the exit to escape. We measured the time intervals between individual escapes in six versions of the experiment, each containing an exit of a different width, to quantify the movement of the groups. As the ants exited the chamber, the time intervals between individual escapes changed and the frequency distribution of the time intervals exhibited exponential decay. We also investigated the relationship between the number of ants in a group and the group flow rate.</p></div

Video recording of ants evacuating from a single-exit room.

<p>The exit width is 2<i>w</i> = 1.0 cm, and a 3.3% concentration of citronella was used.</p

Relationship between the number of ants in a group (<i>S</i>) and <i>Q</i>_<i>S</i> through an exit.

<p>(A), (B) and (C) show the relationship between <i>S</i> and <i>Q</i>_{<b><i>S</i></b>} for the 1<i>w</i> (when <i>N</i>≥2), 2<i>w</i>-6<i>w</i> (when <i>N</i>≥2) and 2<i>w</i>-6<i>w</i> (when <i>N</i>≥3) exit widths, respectively. (A), (B) and (C) reveal a trend toward an increase in <i>Q</i>_{<b><i>S</i></b>} with increasing <i>S</i> only when the exit width was 1<i>w</i> (0.5 cm).</p

<i>Q</i> (mean flow rate) of all of experimental repetitions for the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square represents the <i>Q</i> (mean flow rate) for each exit width. The data indicate no obvious linear relationship between <i>Q</i> (mean flow rate) and <i>d</i> (exit size).</p

Relationship between the value of <i>β</i> and the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square represents the value of <i>β</i> for each exit width, and the solid line represents the result of linear fitting. A trend in which the value of <i>β</i> decreased as the exit width increased is evident.</p

Analysis of the correlation between <i>Q</i>_<i>S</i> and <i>S</i> for the 1<i>w</i> exit width in the evacuation experiments.

<p>It is shown that <i>Q</i>_<i>S</i> and <i>S</i> are significantly correlative.</p><p>^a* Correlation is significant at the 0.05 level (2-tailed).</p><p>^b** Correlation is significant at the 0.01 level (2-tailed).</p><p>Analysis of the correlation between <i>Q</i>_<i>S</i> and <i>S</i> for the 1<i>w</i> exit width in the evacuation experiments.</p

Comparison of time intervals among ant experiments with six exit widths using the t-test.

<p>One, two, and three stars indicate a <i>P</i>-value below 0.05, 0.01, and 0.001, respectively. (A), (B), (C), (D), (E), and (F) show the results of comparisons between the exit widths 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm), with each exit width being compared with every other exit width.</p

Mean <i>Q</i>_<i>S</i> (<i>N</i>≥3) and <i>Q</i> for all experimental repetitions for the six different exit widths.

<p>The six exit widths were 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm). The square and circle represent the mean <i>Q</i>_{<b><i>S</i></b>} and <i>Q</i> for each exit width, respectively. Similar trends exist between mean <i>Q</i>_{<b><i>S</i></b>} and <i>d</i> and between <i>Q</i> and <i>d</i>.</p

Comparison of the number of escaped ants between treatment and control experiments using the t-test.

<p>One, two, and three stars indicate a <i>P</i>-value below 0.05, 0.01, and 0.001, respectively. (A), (B), (C), (D), (E), and (F) compare the results of the 1<i>w</i> (0.5 cm), 2<i>w</i> (1.0 cm), 3<i>w</i> (1.5 cm), 4<i>w</i> (2.0 cm), 5<i>w</i> (2.5 cm), and 6<i>w</i> (3.0 cm) exit widths, respectively. Many more ants escaped during the treatment experiments than during the control experiments.</p

Antennal Transcriptome and Differential Expression Analysis of Five Chemosensory Gene Families from the Asian Honeybee <i>Apis cerana cerana</i>

<div><p>Chemosensory genes play a central role in sensing chemical signals and guiding insect behavior. The Chinese honeybee, <i>Apis cerana cerana</i>, is one of the most important insect species in China in terms of resource production, and providing high-quality products for human consumption, and also serves as an important pollinator. Communication and foraging behavior of worker bees is likely linked to a complex chemosensory system. Here, we used transcriptome sequencing on adult <i>A</i>. <i>c</i>. <i>cerana</i> workers of different ages to identify the major chemosensory gene families and the differentially expressed genes(DEGs), and to investigate their expression profiles. A total of 109 candidate chemosensory genes in five gene families were identified from the antennal transcriptome assemblies, including 17 OBPs, 6 CSPs, 74 ORs, 10 IRs, and 2SNMPs, in which nineteen DEGs were screened and their expression values at different developmental stages were determined in silico. No chemosensory transcript was specific to a certain developmental period. Thirteen DEGs were upregulated and 6were downregulated. We created extensive expression profiles in six major body tissues using qRT-PCR and found that most DEGs were exclusively or primarily expressed in antennae. Others were abundantly expressed in the other tissues, such as head, thorax, abdomen, legs, and wings. Interestingly, when a DEG was highly expressed in the thorax, it also had a high level of expression in legs, but showed a lowlevel in antennae. This study explored five chemoreceptor superfamily genes using RNA-Seq coupled with extensive expression profiling of DEGs. Our results provide new insights into the molecular mechanism of odorant detection in the Asian honeybee and also serve as an extensive novel resource for comparing and investigating olfactory functionality in hymenopterans.</p></div