Social facilitation of eclosion in the fire ant, Solenopsis invicta

Abstract

In colonies of the fire ant, Solenopsis invicta, eclosion is facilitated by adult workers which strip away and consume the pupal cuticle. This stage-specific social interaction involves chemical stimuli which are present at the onset of eclosion, concurrent with the initiation of gross movements and separation of the pupal cuticle. Fire ant workers retrieved inanimate objects treated with an extract of eclosing pupae and placed them in the colony brood chamber with the appropriate age group where they were tended by several workers. The facilitation of eclosion by adult colony members appears to be an obligatory process in the development of this species; pupae denied the aid of adult workers during eclosion are unable to remove the pupal cuticle and rapidly succumb.

Patterns of venom synthesis and use in the fire ant, Solenopsis invicta

“…Each cohort was created by placing late-stage worker pupae from a minimum of 5 different colonies into an 'eclosion tray' with a number of small, adult workers (headwidths # 0.60 mm) to help them eclose (Lamon and Topoff, 1985) (all trays had Fluon-coated sides to prevent ants from escaping; Fluon-Northern Products Inc., Woonsocket, RI). A moist, plaster-floored, darkened petri dish nest, along with fresh water and sugar water (20% v/v) in cotton-plugged test tubes, was provided for each cohort.…”

Do Ant Brood Pheromones Exist?

“…The adequacy of a bioassay to test an hypothesis becomes acute when the test objects are not live animals. A widely used bioassay consists of retrieval of inert objects treated with brood extracts (Glancey et al 1970, Robinson & Cherrett 1974, Walsh & Tschinkel1974, Bigley & Vinson 1975, Brian 1975, LaMon & Topoff 1985, Glancey & Dickens 1988. However, this bioassay can be confounded by food responses as discussed below.…”

“…However, this bioassay can be confounded by food responses as discussed below. To overcome this problem, some experimenters (Walsh & Tschinkel 1974, Brian 1975, LaMon & Topoff 1985 used a nest design that incorporated a distinct brood chamber. Retrieval of tested objects into the brood chamber was used as the criterion for a brood-specific worker response.…”

“…One of the most frustrating inadequacies in many brood pheromone papers (Watkins & Cole 1966, Glancey et al 1970, Bigley & Vinson 1975, LaMon & Topoff 1985 is the lack of information regarding the brood equivalents of the extracts and amount of the control substances used in bioassays. Without this information, it is impossible to determine if a pheromonal response is being tested.…”

“…The most obvious larval behavior is the exchange of liquids with workers (trophallaxis); this exchange is bidirectional and both individuals benefit (Wilson 1971). Although pupae lack noticeable behavior, investigators can recognize eclosing pupae by their gross uncoordinated movements (e.g., LaMon & Topoff 1985). Worker ants may respond to eclosing pupae using these cues.…”