Performance of Arrhenotokous and Thelytokous Thrips tabaci (Thysanoptera: Thripidae) on Onion and Cabbage and Its Implications on Evolution and Pest Management

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is an important pest on onion and cabbage. Two reproductive modes—arrhenotoky and thelytoky—are found in this species and co-occur in the field. We compared life table traits between arrhenotokous and thelytokous T. tabaci on cabbage and onion. Experiments were conducted in cages to determine which reproductive mode is more competitive. Additionally, host adaption of the arrhenotokous and thelytokous T. tabaci between onion and cabbage was investigated. On onion, arrhenotokous T. tabaci performed better than thelytokous T. tabaci, while on cabbage the opposite occurred. When comparing life table and demographic growth parameters (net reproductive rates R0, mean generation time T, the intrinsic rate of natural increase rm, finite rate of increase λ, and population doubling time Td) on different host plants, we found that arrhenotokous T. tabaci performed better on onion than on cabbage, whereas thelytokous T. tabaci performed better on cabbage than on onion. Host-related performance differences in this species suggest that the divergence between two reproductive modes might be associated with host adaption. Pest management strategies for this global pest should recognize that the two reproductive modes can impact population dynamics on different crop

Longevity and lifetime fecundity [means ± SE (n)] of virgin and mated thelytokous <i>Thrips tabaci</i> females.

<p>Normal data. Means within the same column were compared by Student's <i>t</i> test at <i>P</i> < 0.05 level. n: number of replications used in each treatment.</p><p>Longevity and lifetime fecundity [means ± SE (n)] of virgin and mated thelytokous <i>Thrips tabaci</i> females.</p

Survival rates of F₁ immatures from mated and virgin thelytokous female <i>Thrips tabaci</i>.

<p><b>Means within the same stage followed by the same letters are not significantly different at <i>P</i> < 0.05 level according to Student’s <i>t</i> test.</b> F₁: the first generation; L1: first instar; L2: second instar; PP: prepupae; P: pupae.</p

Life table parameters [means ± SE (n)] of F₁ offspring ^a from mated and virgin thelytokous <i>Thrips tabaci</i> females.

<p>^<i>a</i> All the F₁ offspring were females.</p><p>^<i>b</i> Normal data. Means within the same row were compared by Student's <i>t</i> test at <i>P</i> < 0.05.</p><p>^<i>c</i> Non-normal data. Means within the same row were compared by Mann-Whitney <i>U</i> tests at <i>P</i> < 0.05.</p><p>n: number of replications used in each treatment; L1: first instar; L2: second instar; PP: prepupae; P: pupae.</p><p>Life table parameters [means ± SE (n)] of F₁ offspring <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138353#t003fn001" target="_blank">^a</a> from mated and virgin thelytokous <i>Thrips tabaci</i> females.</p

Diagnostic PCR analysis for detection of the arrhenotokous strain and thelytokous strain-originated histone <i>H3</i> gene alleles.

<p>M: DNA Marker; A: arrhenotokous-originated histone <i>H3</i> type; T: thelytokous-originated histone <i>H3</i> type; A/T: both arrhenotokous- and thelytokous-originated histone <i>H3</i> types.</p