Molecular analysis of the gut contents of Harmonia axyridis (Coleoptera: Coccinellidae) as a method for detecting intra-guild predation by this species on aphidophagous predators other than coccinellids

Abstract

Abstract. Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field.

Intraguild predation by Harmonia axyridis (Coleoptera: Coccinellidae) on native insects in Europe: molecular detection from field samples

“…); DNA of E. balteatus could be detected in 80 to 100% of cases 8 h after ingestion by H. axyridis 4th instar larvae, and ingested C. carnea DNA in 80 to 100% of cases after 24 h (Ingels et al . ). The detectability half‐life for 4th instars of H. axyridis feeding on E. balteatus was 25.1 h, while for 4th instars fed with C. carnea the detectability half‐life varied between 32.2 and 52.4 h, depending on the amount of prey eaten (Ingels et al .…”

“…The detectability half‐life for 4th instars of H. axyridis feeding on E. balteatus was 25.1 h, while for 4th instars fed with C. carnea the detectability half‐life varied between 32.2 and 52.4 h, depending on the amount of prey eaten (Ingels et al . ). The feeding trials with A. bipunctata suggest that this half‐life is at least as long as the ones found for C. carnea .…”

“…() (coccinellid detection) and to Ingels et al . () ( E. balteatus and C. carnea detection). Three controls were included on each agarose gel analyzing PCR products: (i) 100% prey DNA; (ii) DNA from a laboratory H. axyridis reared on an aphid only diet; and (iii) distilled water instead of DNA.…”

Development and application of molecular gut‐content analysis to detect aphid and coccinellid predation by Harmonia axyridis (Coleoptera: Coccinellidae) in Italy

“…Intraguild predation (IGP), whereby a predator consumes another species that shares common prey item, has been reported as a common occurrence among coccinellids (Agarwala & Dixon, ; Obrycki et al ., ; Dixon, ; Michaud, ; Lucas, ; Kajita et al ., ). Laboratory and semifield (e.g., cage) experiments suggest that H. axyridis is frequently involved in IGP, acting as a strong and asymmetric predator of other aphidophagous coccinellids (Burgio et al ., ; Michaud, ; Yasuda et al ., ; Gardiner & Landis, ; Pell et al ., ; Ware & Majerus, ; Moser & Obrycki, ; Raak‐van den Berg et al ., ; Rondoni et al ., ; Ingels et al ., ).…”

“…The utilization of molecular gut‐content analysis has become common in assessing food web structure and biological control potential by small and cryptic predators and parasitoids (reviewed by Symondson et al ., ; Harwood & Obrycki, ; Sheppard & Harwood, ; Gariepy et al ., ; Weber & Lundgren, ; Aebi et al ., ), and is a valuable technique for assessing the occurrence of IGP in the field (Schoeller et al ., ; Traugott et al ., ; Davey et al ., ). Molecular (Gagnon et al ., , b; Ingels et al ., ; Thomas et al ., ) and alkaloid‐based (Hautier et al ., , ; Sloggett et al ., ) techniques have been developed and used to document evidence of IGP occurrence by H. axyridis in the field.…”