Temperature-dependent functional response of two aphid parasitoids, Aphidius colemani and Aphidius matricariae (Hymenoptera: Aphidiidae), on the cotton aphid

Abstract

The functional response of two aphid parasitoids, Aphidius colemani Viereck and Aphidius matricariae (Haliday) (Hymenoptera: Aphidiidae), on the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), was examined. Five constant temperatures (10, 15, 20, 25, and 30°C) and six host densities (2, 4, 8, 16, 32, and 64) were used during a 24-h period. At each temperature, 2-64 third-instar nymphs of A. gossypii were exposed to individual wasp mating pairs. A type II functional response model for both parasitoid wasps was fit separately for each temperature. The results showed that instantaneous attack rate (a) in A. colemani increased linearly as the temperature increases from 10 to 30°C, but in A. matricariae, (a) increased almost linearly with temperature to reach a maximum at 25°C, and then decreased at 30°C, displaying an asymmetrical domeshaped pattern. The highest instantaneous attack rate for A. colemani and A. matricariae were calculated 0.940 ± 0.144 day À1 at 30°C and 0.687 ± 0.157 day À1 at 25°C, respectively. Handling time (T h ) for A. colemani was inversely proportional to temperature and ranged from 0.093 ± 0.026 day at 10°C to 0.032 ± 0.004 day at 30°C, but in A. matricariae, (T h ) was between 0.078 ± 0.015 day at 10°C and 0.036 ± 0.014 day at 20°C. A. colemani achieved higher parasitism rate than A. matricariae at higher temperatures. This observation suggests that A. colemani maybe more effective for biological control of the cotton aphid during warmer periods.

Temperature-dependent functional response of Aenasius bambawalei (Hymenoptera: Encyrtidae) to different population densities of the cotton mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae)

“…These results are consistent with the fi nding of a previous study by Feng et al (2014), which report a Holling's Type II response for A. bambawalei attacking third instar nymphs of P. solenopsis at 27 ± 1°C, relative humidity of 70 ± 5% and a photoperiod of 12L : 12D. Several researchers have also studied the effects of constant temperature on the functional response of parasitoids of different species of mealybugs (Flinn, 1991;Joens et al, 2003;Zamani et al, 2006 Functional responses are usually considered to be an important factor in the selection of the most suitable biocontrol agents. Type II functional response is theoretically less capable of suppressing host density compared to the type III functional response (Holling, 1965).…”

“…However, there was a signifi cant decrease in handling time with increase in temperature, which means that at high temperatures there is more time available for searching and a greater probability of fi nding more hosts. Similar fi ndings are reported by Flinn (1991), Menon et al (2002), Jones et al (2003), Zamani et al (2006) and ZandiSohani et al (2008).…”

Development and Parasitism byAphelinus certus(Hymenoptera: Aphelinidae), a Parasitoid ofAphis glycines(Hemiptera: Aphididae)

“…Therefore, our results indicate that searching behavior of A. certus is not random but systematic. Similarly, the type II functional response for Aphidius colemani and A. matricariae to the cotton aphid is best described using HollingÕs disc equation rather than the random predator equation (Zamani et al 2006).…”

Parsing handling time into its components: implications for responses to a temperature gradient

“…) increases exponentially with warming, as predicted by MTE (Zamani et al 2006, Jalali et al 2010, Sentis et al 2012, while two recent meta-analyses reported that this relationship is hump shaped, with a thermal optimum (Englund et al 2011, Rall et al 2012). For both meta-analyses, the authors concluded that high temperatures reduce metabolic reaction rates, suggesting that the MTE equation is not appropriate to predict the effect of temperature on maximum intake rate over large temperature ranges.…”