Temperature Requirements may Explain why the Introduced Parasitoid Quadrastichus citrella Failed to Control Phyllocnistis citrella in Spain

Abstract

Quadrastichus citrella Reina and La Salle (Hymenoptera: Eulophidae) is a parasitoid of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), indigenous to South Eastern Asia where it is considered a key natural enemy of this pest. It was introduced in Spain in a classical biological control program and became established, but was not as successful as forecast. To check whether its biology could explain this lack of control, development and reproduction at different temperatures were studied. Quadrastichus citrella can survive at temperatures between 15 and 35°C. Lower development threshold was 12.3°C, which resulted in a thermal constant of 138.06 DD. The combination of development and reproduction into demographic parameters resulted in highest net reproduction occurring in the range 20-25°C (78.2 females per female), and highest intrinsic rate of increase at 30°C (0.2571 females per female per day). These values make Q. citrella an intrinsically superior natural enemy compared to other leaf miner parasitoids. However, overwintering of Q. citrella in Spain may present a barrier, especially in areas like Valencia, where average winter temperatures are around 11°C. This could account for the low recovery rates observed in Spain in spite of the key natural enemy status enjoyed by this species in its area of origin.

Thermal requirements of Fidiobia dominica (Hymenoptera: Platygastridae) and Haeckeliania sperata (Hymenoptera: Trichogrammatidae), two exotic egg parasitoids of Diaprepes abbreviatus (Coleoptera: Curculionidae)

“…As expected for closely evolved species, such as host-parasitoid assemblages, thermal limits roughly fit within those of the host D. abbreviatus, whose LDT is 128C and UDT 30-328C (Lapointe 2001). Extreme ambient temperatures registered in summer and winter are a crucial factor which can dramatically affect parasitoid establishment in classical biological control programs (Goolsby et al 2005;Llàcer et al 2006). Consequently, summer and winter temperatures in southern and central Florida where D. abbreviatus is distributed can be a key factor that can significantly affect parasitoid development and survival .…”

Reproduction of three eulophid wasps that parasitise larvae of the citrus leafminer

“…In general they laid a single egg in their host and in all cases only a single offspring emerged. This differs from results reported by Llacer et al (2006), who occasionally observed emergence of two Q. citrella adults from a single host. Our results also differ from those reported by Lim and Hoy (2005).…”

“…The biological parameters of Q. citrella measured in our study also differed from those reported by Llacer et al (2006). In our study, the development time of Q. citrella at 258928C (female development) was 10.4690.10 d (Table 2), which is slightly shorter than that found in their study at 258C (10.8390.30 d).…”

“…They used detached citrus leaves in smaller cages, consisting of Petri dishes (250 ml), and also daily transferred the wasps to new cages. The high rate of superparasitism in their study (27.5%) compared to that in our study (1.2%) was probably due to the low number of hosts they offered (Llacer et al 2006).…”

“…Their developmental time was 9Á14 days, longevity was Â40 days. Both show host feeding (Argov and Rö ssler 1998;Lim and Hoy 2005;Llacer, Urbaneja, Garrido, and Jacas 2006) and are synovigenic. Both parasitised the 2ndÁ4th larval instars of CLM, preferring to oviposit female eggs in the 3rd and 4th instars, and over 93% laid a single egg per host.…”