Laboratory Performance Predicts the Success of Field Releases in Inbred Lines of the Egg Parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae)

Abstract

In this study we assessed the relationship between the laboratory and field performance of different isofemale lines of Trichogramma pretiosum Riley. In comparative assays, we used three rare mitochondrial haplotypes as genetic markers of the isofemale lines, and by introgressing these mitochondrial haplotypes into each of 15 genetically different nuclear lines, also tested the assumption that mitochondria are neutral markers. In a laboratory trial, 45 isofemale lines (15 nuclear genotypes x three mitochondrial haplotypes) were ranked in three categories (best, intermediate and worst) according to the mean offspring production and the proportion of female offspring. Subsequently, lines from each of the three categories were selected for field releases to quantify field parasitism on Ephestia kuehniella. Temporally separate releases were done in a transgenic Bt cornfield, with four plots, each with 50 points of recapture. The points of recapture consisted of trap cards with eggs of E. kuehniella collected daily. The trap cards were maintained in the laboratory at 25°C until the adult wasps emerged, and the maternal identity of the wasps was determined using qPCR and high-resolution melt curve analysis to determine the mitochondrial haplotype. The results showed that these measures of laboratory performance (fecundity and offspring sex ratio) were good predictors of field success in T. pretiosum. We also report strong evidence discrediting the assumption that mitochondria are neutral, in view of the correlation between performance and mitochondrial haplotype.

Demographic parameters of the indigenous egg parasitoids, Trichogramma spp., parasitizing the invasive tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

“…The successful use of Trichogramma spp. in biological control depends on knowledge of their biotic potential against the target pest and the thermal requirements (Coelho et al 2016). Different Trichogramma species and/or strains differ in their efficiency against the target pest, thus, making it necessary to study the performance of different species/strains of Trichogramma on the target pest (Bueno et al 2009).…”

Lifetime inbreeding depression in a leaf beetle

“…However, the extent of inbreeding depression under benign laboratory conditions may not precisely predict the magnitude of inbreeding depression under more stressful field conditions in natural populations (Armbruster & Reed, ). Some studies illustrated that results gained from laboratory‐reared populations can predict the performance of wild populations under field conditions (Coelho, Rugman‐Jones, Reigada, Stouthamer, & Parra, ; Fox et al., ). Nevertheless, there is broad evidence that the magnitude of inbreeding depression is higher under stressful field conditions relative to benign laboratory conditions (Fox & Reed, ).…”

Flight Propensity of Isofemale Lines ofTrichogramma pretiosumRiley in Two Relative Humidity Levels

“…We used backcrossing protocols to create 3 populations of each isofemale line marked by nuclear DNA, and each population differed only in its mitochondrial marker. The rearing protocol for these populations followed the method described by Coelho Jr. et al (2016), primarily always using 1 female offspring crossed with 1 male with known nuclear DNA.…”

“…The isofemale lines used in the flight tests were the same lines that were used in the field experiments by Coelho Jr. et al (2016). These lines were classified into 3 categories: "best" isofemale lines with the highest fertility and sex ratio; "intermediate" isofemale lines with medium levels of fertility and sex ratio; and "worst" isofemale lines with the poorest reproductive capacity (fertility and sex ratio) (see Table 1).…”

“…According to van Lenteren (2003), this flight test was adopted as a standard by the International Organization for Biological Control (IOBC). Trichogramma strains differ in many of their biological parameters; among others, their flight propensity in the field and laboratory (Cerutti & Bigler 1995), reproductive performance in the field and laboratory (Sorati et al 1996;Thomson & Hoffmann 2002;Guzmán-Larralde et al 2014), and parasitism and dispersal capacity in field conditions (Bourchier & Smith 1996;Dutton et al 1996;Fournier & Boivin 2000;Coelho Jr. et al 2016). Little is known about the effect of environmental factors on the flight propensity of Trichogramma and its variation within species.…”