Effect of wind time on the dispersal capacity of Trichogramma dendrolimi Matsumura (Hymenoptera Trichogrammatidae)

The efficacy of Trichogramma against pests basically depends on the dispersal capacity of the wasps. A release-recapture method was used in this study to evaluate the effect of relative wind speed (RWS) during the nighttime and the daytime on the dispersal capacity of postrelease population of Trichogramma dendrolimi Matsumura. Two repeated measurements were carried out, using sentinel cards with the host eggs and yellow sticky card traps on the third and the sixth day after wasp release. The results showed that: (1) both the number of recaptured wasps and parasitized eggs increased with the RWS in the daytime during the first three days. The number of parasitized eggs also increased with the RWS in the daytime over the latter three days. The distances that encompassed 98% recaptured T. dendrolimi adults (X-98) at the first three days was quadratically increased by the RWS of the daytime. (2) The number of wasps recaptured decreased with the distance from the releasing point during the first three days, but it was not influenced by the distance from the releasing point during the latter three days. (3) The average dispersal radius of the wasps during the first three days was shorter than during the latter three days. The present results will be helpful to improve release techniques based on the wind effects at different times.