PATTERNS OF HOST UTILIZATION BY CATOLACCUS GRANDIS, AN EXOTIC PARASITE OF BOLL WEEVIL: EFFECTS OF HOST MICROHABITAT

Authors: Summy, Kenneth; GREENBERG, SHOIL - TX AGRI EXPER STATION; MORALES-RAMOS, JUAN - TX AGRI EXPER STATION

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Studies were conducted under laboratory conditions to determine the effects of host microhabitat on the incidence of attack by the parasitic wasp Catolaccus grandis. The parasite readily attacked immature boll weevils occurring in cotton flower buds (squares), regardless of whether these occurred within the cotton canopy or were distributed on the soil surface (squares tend to abcise following oviposition by boll weevils). In contrast, attacks on immature weevils infesting the fruit (bolls) were restricted to those which exhibited some type of damage (e.g., separated carpel walls) that presumably provided access to the parasite's ovipositor (the egg-laying apparatus). Results of these studies demonstrated that immature boll weevils infesting squares are susceptible to attack by C. grandis, regardless of location within the cotton habitat. Attacks among immature hosts infesting bolls appear to be governed by the physical condition of the fruiting form itself: hosts infesting damaged bolls appea to be highly susceptible to attack, whereas those occurring within undamaged bolls are largely protected from attack by this parasite species.

Technical Abstract: Research was conducted to investigate the effects of host microhabitat on the incidence of oviposition by Catolaccus grandis (Burks), an exotic parasite of boll weevil, Anthonomus grandis Boheman. Third-instar boll weevil larvae and pupae infesting cotton squares were shown to be highly susceptible to attack by C. grandis, regardless of location within the cotton habitat (i.e., within the canopy or on the soil surface following abcision). In contrast, the susceptibility of immature host stages infesting cotton bolls was shown to be largely predicated on the physical condition of the individual fruiting form. Third-instar boll weevil larvae and pupae infesting bolls characterized by separated carpel segments or other types of surface damage (which presumably provide access to the parasite's ovipositor) were readily parasitized, whereas contemporaries infesting fresh (undamaged) bolls appear to have been largely protected from attack by this parasite species.