Aspects of life‐table studies and functional response of Lysiphlebia mirzai

Abstract

The fecundity, reproductive rate, and survival of Lysiphlebia mirzai parasitising third instar nymphs of the cereal aphid Rhopalosiphum maidis were measured at six different host densities under constant laboratory conditions. The survival rate (lx) of the female parasitoids was unaffected by host density, with an average adult life‐span of 5–6 days at all densities. The age‐specific fecundity rate (mx) was host density‐dependent. The value of mx decreased rapidly from the first day of parasitisation. The number of hosts available determined the maximum possible number of mummies. At 200 hosts available per day, the average fecundity was 184.6 mummies/female; the maximum number of mummies yielded by any female was 200. The relationship between host density and the number of aphids parasitised per female was linear at ≤50 aphids/cage/day, but at higher host densities (≥100 aphids/cage/day) a significant curvilinear regression was observed. The intrinsic rate of natural increase (rm) increased with increasing host density. Maximum value of rm (0.262) was obtained at a host density of 200. The response of rm to changes in host density and parasitoid sex ratio is shown. A typical type II functional response was observed for L. mirzai. The curve was described by a logistic curve, Np = 200/[1 + exp(5.65 − 1.60 ln No)]. The search rate of the parasitoid was inverse host density‐dependent. No significant variation in the sex ratio of F1 offspring was observed at different initial host densities. Sex ratio values exceeded 0.5 at all host densities. The results evaluated the reproductive potential of L. mirzai as a promising biological control agent.

Host instar preference and functional response of Aphidius transcaspicus, a parasitoid of mealy aphids (Hyalopterus species)

“…In contrast to the shape of the functional response, the level of the upper asymptote of the response, which represents the maximum daily number of aphids parasitized, may be more indicative of the biological control potential of these aphid parasitoids. In this context, the upper asymptote of 64.3 aphids day -1 for A. transcaspicus places this species among those with the greatest daily parasitism potential (58-70 aphids day -1 ) as found for Aphidius colemani (Jones et al 2003;Byeon et al 2011), Diaeretiella rapae (Bernal et al 1994), Ephedrus cerasicola (Hofsvang and Hagvar 1983), Lysiphlebus testaceipes (Hughes et al 1992;Jones et al 2003), and Lysiphlebia mirzai (Tripathi and Singh 1991). Most other Aphidius species that have been studied have lower upper asymptotes from seven to 30 aphids day -1 (Hughes et al 1992;Zamani et al 2006;Tahriri et al 2007), and from five to 46 aphids day -1 for Trioxys and Aphelinus species, and Lysiphlebus fabarum (Collins et al 1981;Hughes et al 1992;Rakhshani et al 2004;Mahmoudi et al 2010).…”

Effect of host density, temperature, and photoperiod on the fitness of Anagyrus kamali, a parasitoid of the hibiscus mealybug Maconellicoccus hirsutus

“…However, it is an essential component of the dynamics of host-parasitoid association, and an important determinant of the stability of the system (Wang & Ferro, 1998). As many other Hymenoptera, A. kamali should exhibit a type II or III functional response which correspond to either an inverse density dependence (Tripathi & Singh, 1991), or a positive density dependence (Pandey et al, 1984), respectively. The effect of host density on the female parasitoid progeny emergence and sex-ratio was also determined.…”

Parasitismo da cochonilha-farinhenta Planococcus citri (Hemiptera: Pseudococcidae) por Coccidoxenoides perminutus (Hymenoptera: Encyrtidae) 1

“…A resposta funcional de parasitoides atacando pseudococcídeos em laboratório tem variado entre resposta funcional do tipo II (Tripathi & Singh, 1991) ou tipo III (Pandey et al, 1984). O parasitoide Anagyrus kamali (Hymenoptera: Encyrtidae) parasitando Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), sob condições de tempo fixo e tempo variável, apresentou resposta funcional do tipo II e III em tempo fixo e, apenas do tipo III em tempo variável (Sagarra, 2000).…”