Effect of temperature on the reproduction and development of Trichogramma buesi (Hymenoptera: Trichogrammatidae)

Abstract

Abstract. At emergence females of Trichogramma had a lot of mature eggs in their ovaries, but some delayed parasitization or refused to parasitize a laboratory host. The effect of constant and alternating temperatures on the percentage of Trichogramma buesi females parasitizing Sitotroga cerealella eggs and the duration of the pre-parasitization period were investigated. The temperature dependencies of the rate of preimaginal development, pre-emergence survival, number of eggs laid daily, and total lifetime fecundity were also determined. As the temperature was increased from 12 to 35°C, the median pre-oviposition period decreased from 5 days to 3 h, with maximum values of 24 and 1.5 days, respectively. The rate of induction of parasitization (reciprocal of duration of the pre-parasitization period of the females that parasitized) increased with temperature like the rate of preimaginal development and average number of eggs laid daily by a parasitizing female. Total cumulative percentage of parasitizing females reached a maximum (ca 60%) at temperatures of 25-30°C, while at 12 and 35°C, respectively, 25 and 50% of females parasitized the S. cerealella eggs. Average lifetime fecundity and pre-emergence survival showed a similar dependence on temperature. The influence of the thermorhythm (25°C for 4 h and 15°C for 20 h) was strongly dependent on its position within the photoperiod. When thermophase coincided with photophase, the percentage of females that parasitized was close to that recorded at a constant temperature of 25°C. But when the high temperature pulse coincided with the dark period, the percentage of parasitizing females was the same as at 15°C. Thus, the temperature dependence of ethogenesis (supposedly, an increase in motivation to parasitize or search for a host) in Trichogramma females was similar to that of morphogenesis, although the reaction to alternating temperatures may have been complicated by interaction with the light : dark regime.

Role of host diet on the fitness of the egg parasitoid species, Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae)

“…These results are in accordance with other studies showing that T. evanescens laid more eggs in the first 24 h (Achiri et al 2020). It is known that the mean number of eggs laid per female generally decreases over time or with the age of the parasitoid (Reznik et al 2009). Trichogramma chilonis Ishii on eggs of C. cephalonica and T. cacoeciae on Cydia pomonella (Linnaeus, 1758) (Lepidoptera: Tortricidae) eggs showed a systematic decrease in the numbers of eggs laid per female over time (Mansour 2019).…”

Performance of four Trichogramma species (Hymenoptera: Trichogrammatidae) as biocontrol agents of Heliothis virescens (Lepidoptera: Noctuidae) under various temperature regimes

“…In our experiments, parasitism rate was affected by temperature for each all four Trichogramma species, though all females did parasitize at least one egg under all temperature regiments tested (which is not always the case, see Reznik et al 2009). The variation in parasitism rate may be the result of local adaptation to the various climatic conditions where each species was collected.…”

Effect of an introduced parasite in natural and anthropogenic habitats on the breeding success of the endemic little vermilion flycatcher Pyrocephalus nanus in the Galápagos

“…Other potential factors include higher host numbers or species (Wiedenfeld et al ) or host phenotypes and genotypes that sustain much higher infestation intensities. In addition average temperatures are lower at higher altitudes, which is known to affect P. downsi development and infestation intensity negatively (Mosquera ), as also shown for other insects (Taylor , Ratte , Reznik et al ). A recent study in Santa Cruz found low P. downsi activity, as shown by low numbers in fly traps when temperatures were below ~19–21°C (Causton et al ).…”