Effect of the instar of the pear psyllid Cacopsylla pyri (Hemiptera: Psyllidae) on the behaviour and fitness of the parasitoid Trechnites insidiosus (Hymenoptera: Encyrtidae)

Abstract

Improved methods of integrated pest management of the pear psyllid Cacopsylla pyri (L.), the primary pest of pear in Europe and North America, are needed. Trechnites insidiosus (Crawford) is the most abundant parasitoid of C. pyri in pear orchards, where it is present early in the psyllid infestation period. However, little is known about its general biology, interaction with its host and potential as a control agent. The objective of this laboratory study was to evaluate the behaviour of a specialist parasitoid when presented with different larval instars of C. pyri, and assess the quality of the next generation of parasitoids. T. insidiosus was able to insert its ovipositor into all host instars. However, the fourth instar of the host appeared to be the most suitable in terms of behavioural acceptance, time spent walking, antennal activity and progeny development (mummy formation, development time and tibial length). In addition, we report a low frequency of host-feeding behaviour by this parasitoid. From a biological control perspective, we suggest that favouring T. insidiosus, either through mass releases or conservation of naturally present populations, when the first generation of psyllids reach the fourth instar, would maximize the chance of controlling psyllid populations in pear orchards.

Keywords

• psyllidae
• cacopsylla pyri
• encyrtidae
• trechnites insidiosus
• parasitoid
• behaviour
• host instar
• locomotor activity
• host acceptance
• host suitability
• offspring quality
• pear orchards
• biological control