properties that may also vary in terms of searching efficiency or handling time.
However, this hypothesis needs to be validated.
The effect of different factors on searching efficiency and handling time of
H. variegata has been evaluated. Prey types, developmental stages of predator
(Bigdelou 2012; Farhadi et al. 2010; Madadi et al. 2011), experimental scale, host
cultivar properties (Behnazar and Madadi 2015), temperature (Asghari et al. 2012;
Ebrahimi Arfaa 2014), predator sex (Farhadi et al. 2010; Hassankhani and Allahyari
2013) and even some pesticides (Alimohammadi Davarani et al. 2012) are among
the factors that have been surveyed but still it seems that the influence of many other
traits (e.g. moisture, host plant qualities, feeding history and plant structure) on
functional response of H. variegata should be addressed.
H. variegata, as a dominant lady beetle species of most parts of Iran, attracted
most of attention to itself and it is more studied than any native lady beetle species. In
addition to this species, the sporadic researches have been done on functional
response of other species more or less. Similar to most H. variegata studies, it has
been reported that A. bipunctata (Linnaeus 1758) exhibited type II response, while
the fourth instar larvae had higher searching efficiency and lower handling time than
females to pomegranate aphids, A. punicae (Dehghan Dehnavi et al. 2007).
There are a few studies dealing with the functional response of lady beetles to
herbivorous mites. Most of these studies have been focused on functional response
studies with S. gilvifrons (Mulsant), a major predator of different aphid species
especially in South of Iran, mainly found in sugarcane and castor bean fields
(Hajizadeh 1995; Modarres Awal 2001; Afshari et al. 2007; Mehrkhou et al. 2008)
(Table 2.4). All such studies except Sohrabi and Shishehbor (2007), exhibited a type
II response for S. gilvifrons. This could be doubtful, mainly because they did not
specify the analysis method used for determining the type of response. The noticeable point in S. gilvifrons studies is low attack constant and long handling time to
strawberry spider mite (Sohrabi and Shishehbor 2007). Imani et al. (2009) reported
the type II functional response of S. gilvifrons Mulsant females to different life stages
of citrus brown mite, Eutetranychus orientalis Klein on leaf discs. Accordingly, they
reported that among stages, ladybeetle females had the lowest handling time for
citrus brown mite larvae. In another study, functional response of all predatory stages
of S. gilvifrons to E. orientalis (Klein) eggs assessed. Similarly, using the same prey,
the fourth instar larvae of S. gilvifrons showed the maximum predation rate relative
to females and third instar larvae. This was not unpredictable, but the striking point
in their results was that the instantaneous searching rate of S. gilvifrons female was
lower than all other tested stages, even the first instar larvae (Imani and Shishehbor
2011). Of course, they did not compare the results statistically, but 95% confidence
intervals of searching efficiency were overlapped, which might imply nonsignificant
difference in results. In terms of handling time, the fourth instar larvae and females
have the most voracious life stages of S. gilviforns similar to aphidophagous lady
beetles. Approximately all of these studies have been conducted under artificial
laboratory conditions. This might be inevitable because the size of predator and prey
mites is tiny and recording the number of killed prey is not possible easily without
examining under stereomicroscope. It should be noted that apart from S. gilvifrons
64
H. Madadi
However, this hypothesis needs to be validated.
The effect of different factors on searching efficiency and handling time of
H. variegata has been evaluated. Prey types, developmental stages of predator
(Bigdelou 2012; Farhadi et al. 2010; Madadi et al. 2011), experimental scale, host
cultivar properties (Behnazar and Madadi 2015), temperature (Asghari et al. 2012;
Ebrahimi Arfaa 2014), predator sex (Farhadi et al. 2010; Hassankhani and Allahyari
2013) and even some pesticides (Alimohammadi Davarani et al. 2012) are among
the factors that have been surveyed but still it seems that the influence of many other
traits (e.g. moisture, host plant qualities, feeding history and plant structure) on
functional response of H. variegata should be addressed.
H. variegata, as a dominant lady beetle species of most parts of Iran, attracted
most of attention to itself and it is more studied than any native lady beetle species. In
addition to this species, the sporadic researches have been done on functional
response of other species more or less. Similar to most H. variegata studies, it has
been reported that A. bipunctata (Linnaeus 1758) exhibited type II response, while
the fourth instar larvae had higher searching efficiency and lower handling time than
females to pomegranate aphids, A. punicae (Dehghan Dehnavi et al. 2007).
There are a few studies dealing with the functional response of lady beetles to
herbivorous mites. Most of these studies have been focused on functional response
studies with S. gilvifrons (Mulsant), a major predator of different aphid species
especially in South of Iran, mainly found in sugarcane and castor bean fields
(Hajizadeh 1995; Modarres Awal 2001; Afshari et al. 2007; Mehrkhou et al. 2008)
(Table 2.4). All such studies except Sohrabi and Shishehbor (2007), exhibited a type
II response for S. gilvifrons. This could be doubtful, mainly because they did not
specify the analysis method used for determining the type of response. The noticeable point in S. gilvifrons studies is low attack constant and long handling time to
strawberry spider mite (Sohrabi and Shishehbor 2007). Imani et al. (2009) reported
the type II functional response of S. gilvifrons Mulsant females to different life stages
of citrus brown mite, Eutetranychus orientalis Klein on leaf discs. Accordingly, they
reported that among stages, ladybeetle females had the lowest handling time for
citrus brown mite larvae. In another study, functional response of all predatory stages
of S. gilvifrons to E. orientalis (Klein) eggs assessed. Similarly, using the same prey,
the fourth instar larvae of S. gilvifrons showed the maximum predation rate relative
to females and third instar larvae. This was not unpredictable, but the striking point
in their results was that the instantaneous searching rate of S. gilvifrons female was
lower than all other tested stages, even the first instar larvae (Imani and Shishehbor
2011). Of course, they did not compare the results statistically, but 95% confidence
intervals of searching efficiency were overlapped, which might imply nonsignificant
difference in results. In terms of handling time, the fourth instar larvae and females
have the most voracious life stages of S. gilviforns similar to aphidophagous lady
beetles. Approximately all of these studies have been conducted under artificial
laboratory conditions. This might be inevitable because the size of predator and prey
mites is tiny and recording the number of killed prey is not possible easily without
examining under stereomicroscope. It should be noted that apart from S. gilvifrons
64
H. Madadi