Abstract
BackgroundCompared to chemical control, the use of naturally occurring biological agents to control invasive pests is less threatening to the environment and human health.ObjectivesHere, we assessed the ability of immature stages of the lacewing Ceraeochrysa caligata (Neuroptera: Chrysopidae) to prey upon different developmental stages of the red palm mite Raoiella indica (Acari: Tenuipalpidae), one of the most destructive invasive pests of palm trees in Neotropical regions.MethodsIncreasing densities of three stages of R. indica (eggs, immature stages, and adult females) were offered to C. caligata in coconut leaf arenas. The immature stages of C. caligata were less than 24 h old and were starved before being transferring to the arenas. The amount of prey consumed was recorded 6 h after releasing the C. caligata.ResultsOur results indicated that the ability of C. caligata to feed upon R. indica increased with the larval development of the predator. Higher feeding levels and shorter handling times were recorded for the first and second instars of C. caligata when preying upon the eggs and immature stages of R. indica. Furthermore, C. caligata individuals of different stages exhibited differential functional responses according to prey type (i.e., eggs, immatures, or adult females of R. indica). Ceraeochrysa caligata second instar individuals exhibited a sigmoid increase in consumption rate with increasing prey availability (i.e., a type III functional response) when preying upon immature stages of R. indica. However, when preying upon R. indica adult females, C. caligata second instar individuals exhibited a type II functional response (i.e., an increase in consumption rate with increasing prey availability, before reaching a plateau). Predator individuals of the first and third instar stages exhibited a type II functional response for all prey types.ConclusionsCollectively, our findings demonstrate that C. caligata, especially at the second instar stage, has potential as a tool for ecological management of the red palm mite.
Highlights
The red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), is a severe pest of a myriad of ecologically and agriculturally important crops (Carrillo et al, 2012a), especially palm trees (De Assis, De Morais & Gondim, 2013)
The functional response curves for the C. caligata individuals of three larval instars indicated that the number of R. indica eggs, immatures, or adult females consumed by C. caligata rapidly increased with increasing prey density (Fig. 1)
Whereas logistic regression yielded a significant (P < 0.001) negative linear coefficient for the first and third instars of C. caligata feeding upon all prey stages (Table 1), the second instar individuals of C. caligata exhibited a type III functional response when feeding upon eggs and immatures of R. indica but a type II functional response when preying upon adult females of R. indica (Table 1)
Summary
The red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), is a severe pest of a myriad of ecologically and agriculturally important crops (Carrillo et al, 2012a), especially palm trees (De Assis, De Morais & Gondim, 2013). The use of synthetic compounds remains the most prevalent strategy to control R. indica in coconut plantations (Jayaraj, Natarajan & Ramasubramanian, 1991; Rodrigues & Peña, 2012), despite the need for frequent applications and the risks associated with these control tools (e.g., threats to human health, contamination of the environment, and selection of resistant individuals). C. caligata individuals of different stages exhibited differential functional responses according to prey type (i.e., eggs, immatures, or adult females of R. indica). Ceraeochrysa caligata second instar individuals exhibited a sigmoid increase in consumption rate with increasing prey availability (i.e., a type III functional response) when preying upon immature stages of R. indica. Our findings demonstrate that C. caligata, especially at the second instar stage, has potential as a tool for ecological management of the red palm mite
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