Cuticular encystment in three noctuid species (Lepidoptera): induction by acid gland secretion from an ichneumonid parasite (Banchus flavescens).
In response to internal parasitism by Banchus flavescens Cress., larvae of Trichoplusia ni (Hb.) and, to somewhat lesser degrees, larvae of Anagrapha falcifera (Kby.) and Plusia californica Speyer (Autographa californica) were found to form a bubble-like cyst between the cuticle and epidermis on the dorsum of the penultimate segment. Larvae of Heliothis ononis (Schiff.) and Discestra trifolii (Hfn.) (Scotogramma trifolii) do not respond in this way; they promptly and effectively encapsulate the parasites within their haemocoel. The stimulant for cyst formation in the larvae seems to be produced by the acid (= poison) accessory gland of the female parasite; this same secretion serves to protect the parasite from haemocytic encapsulation.