There is a clear relationship between maximum attack rate of a parasitoid in a
functional response study and daily parasitism of a parasitoid in life table studies.
Daily parasitism in an unlimited environment may reflect maximum daily attack rate
of a parasitoid of age x. Unfortunately, in many functional response studies,
age-specific attack rates were neglected. Amir-Maafi’s (2000) study is an exception.
In most studies, the functional response of newborn females or those of a specific age
only included. However, life table studies reveal that parasitism often varies
age-dependently. A general pattern is not obvious in different studies, but except
T. grandis in Amir-Maafi’s (2000) study in which a gradual decrease occurred, in
other studies, a sudden decline in parasitism occurred (Nozad-Bonab et al. 2014;
BenaMolaei 2014; Abdi 2014). Hence, parasitism of the first day is often the highest.
Sometimes parasitism reaches the maximum at the second or third day because all
females do not emerge on the same day. Maximum of oviposition occurs at the first
week of oviposition (62.8% in T. grandis and 63–84% in T. vassilievi (Amir-Maafi
2000; BenaMolaei 2014). After the 10th day, only 10–20% of total fecundity
realizes. Oviposition often terminates at the end of the third week of oviposition
and seldom continues at 4th week. Therefore, one week old or younger females are
the best candidates not only in functional response studies but also in releasing
programs. Oviposition pattern is somewhat different in Ooencyrtus spp. It takes
longer and with the lower daily rate. It is high at initial 10 days with limited
fluctuations, but often reaches a maximum at the 3rd–7th day of oviposition and
then suffers a sharp decline (Rafat et al. 2013; Ahmadpour et al. 2013).
A comparison among different species is not a straightforward task. At first
physical conditions, particularly temperature and host quality must be similar.
Secondly, parameter estimation based on classic fixed-time single-patch experiments
bears heavy biases. Direct observation on handling time, comparisons among experiments with equal total times or comparison among daily attack rates (24 h-based
estimates of T/T h i.e. 24/T h ) is a solution.
Type III functional response seems to be the most common among sunn pest’s
egg parasitoids (Abdi et al. 2015). This is true for T. vassilievi (BenaMolaei et al.
2018b) and O. fecundus (Iranipour et al. 2013a) on E. integriceps eggs, and four
species of Trissolcus spp. on Echistus hero F. (Laumann et al. 2008). The response
of O. telenomicida to sunn pest eggs was type II (Iranipour et al. 2013b), and that of
the T. grandis and T. semistriatus was host-dependent. The response of the
T. semistriatus to E. integriceps and Graphosoma lineatum L. was type II and III
respectively (Asgari et al. 2001). The response of T. grandis to both E. integriceps
and Podissus maculiventris Say was type III (Allahyari et al. 2004), while the
functional response of 2–11 day old females of T. grandis was type II (AmirMaafi 2000).
In a few studies, direct observations were done upon parasitoid’s behaviour, but
whenever such observations are made, a comprehensive conclusion is possible. For
example, Amir-Maafi (2000) showed that the actual handling time of T. grandis is
three mins, whereas model estimate was 17 mins. Furthermore, the maximum attack
rate estimated to be 85 d
À1 where the actual rate was 28. This is because parasitoid is
egg-limited rather than time-limited. Similar handling time was recorded for
316
S. Iranipour
functional response study and daily parasitism of a parasitoid in life table studies.
Daily parasitism in an unlimited environment may reflect maximum daily attack rate
of a parasitoid of age x. Unfortunately, in many functional response studies,
age-specific attack rates were neglected. Amir-Maafi’s (2000) study is an exception.
In most studies, the functional response of newborn females or those of a specific age
only included. However, life table studies reveal that parasitism often varies
age-dependently. A general pattern is not obvious in different studies, but except
T. grandis in Amir-Maafi’s (2000) study in which a gradual decrease occurred, in
other studies, a sudden decline in parasitism occurred (Nozad-Bonab et al. 2014;
BenaMolaei 2014; Abdi 2014). Hence, parasitism of the first day is often the highest.
Sometimes parasitism reaches the maximum at the second or third day because all
females do not emerge on the same day. Maximum of oviposition occurs at the first
week of oviposition (62.8% in T. grandis and 63–84% in T. vassilievi (Amir-Maafi
2000; BenaMolaei 2014). After the 10th day, only 10–20% of total fecundity
realizes. Oviposition often terminates at the end of the third week of oviposition
and seldom continues at 4th week. Therefore, one week old or younger females are
the best candidates not only in functional response studies but also in releasing
programs. Oviposition pattern is somewhat different in Ooencyrtus spp. It takes
longer and with the lower daily rate. It is high at initial 10 days with limited
fluctuations, but often reaches a maximum at the 3rd–7th day of oviposition and
then suffers a sharp decline (Rafat et al. 2013; Ahmadpour et al. 2013).
A comparison among different species is not a straightforward task. At first
physical conditions, particularly temperature and host quality must be similar.
Secondly, parameter estimation based on classic fixed-time single-patch experiments
bears heavy biases. Direct observation on handling time, comparisons among experiments with equal total times or comparison among daily attack rates (24 h-based
estimates of T/T h i.e. 24/T h ) is a solution.
Type III functional response seems to be the most common among sunn pest’s
egg parasitoids (Abdi et al. 2015). This is true for T. vassilievi (BenaMolaei et al.
2018b) and O. fecundus (Iranipour et al. 2013a) on E. integriceps eggs, and four
species of Trissolcus spp. on Echistus hero F. (Laumann et al. 2008). The response
of O. telenomicida to sunn pest eggs was type II (Iranipour et al. 2013b), and that of
the T. grandis and T. semistriatus was host-dependent. The response of the
T. semistriatus to E. integriceps and Graphosoma lineatum L. was type II and III
respectively (Asgari et al. 2001). The response of T. grandis to both E. integriceps
and Podissus maculiventris Say was type III (Allahyari et al. 2004), while the
functional response of 2–11 day old females of T. grandis was type II (AmirMaafi 2000).
In a few studies, direct observations were done upon parasitoid’s behaviour, but
whenever such observations are made, a comprehensive conclusion is possible. For
example, Amir-Maafi (2000) showed that the actual handling time of T. grandis is
three mins, whereas model estimate was 17 mins. Furthermore, the maximum attack
rate estimated to be 85 d
À1 where the actual rate was 28. This is because parasitoid is
egg-limited rather than time-limited. Similar handling time was recorded for
316
S. Iranipour