Background
Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) is an illustrious predator that performs cannibalism upon facing small and defenseless conspecifics. Eating preference of C. carnea larvae was investigated between conspecific and host (Sitotroga cerealella) eggs. Early instars of C. carnea express significant preference toward conspecific eggs over host eggs. Experiments were carried out to examine the role of conspecific neighbors in execution of cannibalistic decision. These cannibalistic behaviors of larvae were also investigated through locomotion bioassays using the video tracking software ANY-maze®.
Results
Larvae commit low egg cannibalism when alone but express higher cannibalism in the presence of conspecific larvae in the neighborhood. The role of relatedness in egg cannibalism was investigated when larvae were offered a choice between conspecific eggs from related and unrelated parents. Larvae did a discrimination between eggs of their own parents and those of other parents.
Conclusion
Behavioral bioassays showed attraction toward conspecific eggs and the eggs of unrelated parents. This study emphasizes the significance of informational and descriptive cues that modulate the cannibalistic expression in C. carnea.
Background
Attraction and oviposition preference of the green lacewing, Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae), in response to prey availability in an ovipositional site was studied. The study aimed to investigate whether an adult attraction of C. carnea to oviposition on the substrate was affected by aphid juice (AJ) of fresh brassica aphid, Brevicoryne brassica.
Result
In laboratory bioassay, the number of eggs laid by female was significantly higher on AJ-treated area of substrate than control, indicating that oviposition was influenced by the AJ application. Attraction period of AJ lasted for 4 days. In Y-maze olfactometer studies, video tracking software ANY-maze® indicated that C. carnea spent significant more time in the novel arm provided with AJ, showing an attraction. In the greenhouse study, AJ spray attracted a significantly higher number of male and female and considerably increased the number of eggs laid on brassica plant.
Conclusion
Fresh AJ may be a potential attractant for raising population of this predatory species at a particular location without being involved in rearing and augmentation process. This finding is of special interest and may be of benefit in biological control. As it is likely that the AJ spray could be used to enhance C. carnea population attraction to the desire field.
The reported high loss mortality rate of green lacewing, (Chrysoperla carnea) have been attributed to diverse factors including unattended use of insecticides. Since chemical control is one of a significant practice to manage insect pest in cotton. However, this kind of practice may impair the natural control provided by generalist predator C. carnea. Although, natural control adoption is limited in crops, area and season due to wide-spread use of insecticides but presence of resistance potential in C. carnea may improve the design of solid IPM strategies. Herein, we aimed to assess the toxicity of four insecticides to two strains of C. carnea (viz. laboratory reared and field collected adults) and to evaluate their resistance potential by calculating their resistance ratio. LC 50 was calculated at 24 h following topical application administered when the adults were 3 days old. Control adult mortalities were less than 10% at 24 h. The LC 50 values (µl mL -1 ) for laboratory reared strains of each tested insecticide were: acetamiprid, 0.0064; bifenthrin, 3.75; chlorpyrifos, 0.067; and profenofos, 0.052. The LC 50 values for field collected strains were 0.096 (acetamiprid), 34.8 (bifenthrin), 0.21 (chlorpyrifos) and 0.44 (profenofos). The toxicity of the test insecticide to C. carnea from more to least toxic was acetamiprid > profenofos > chlorpyrifos > bifenthrin. Field collected strain possessed 15 (acetamiprid)-, 9.28 (bifenthrin)-, 3.13 (chlorpyrifos)-, and 8.5 (profenofos)-fold more resistance than the susceptible population. These results are pretty worthwhile for integration of C. carnea in IPM programs, impairing with insecticides.
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