Pathogenesis associated with philornid myiasis (Diptera: Muscidae) on nestling pearly-eyed thrashers (Aves: Mimidae) in the Luquillo Rain Forest, Puerto Rico.

Pathogenesis of myiasis due to the muscid fly Philornis deceptivus in nestling pearly-eyed thrashers (Margarops fuscatus) in the Luquillo Rain Forest, Puerto Rico was investigated. Philornid larvae penetrated the host integument, underwent a period of development and growth, and established, as third instar larvae, between the dermis and the body musculature. Movement into this location plus growth and development of the fly larva appeared to be linked to the ingestion of host tissues including red blood cells, mononuclear cells which infiltrated from focal accumulations adjacent to the lesion, and necrotic cellular debris which accumulated in the lesion. The resultant increase in size of the larvae greatly displaced the host integument. Following the evacuation of the larvae for the purpose of pupation, repair of the cavernous lesion was initiated with the production of an intense organized fibrinous exudate. Macrophages and plasma cells predominated with vascular congestion in surrounding tissues. Over the 21-day nest period, nestlings were subject to successive infestations of large numbers of larvae and host responses to these appeared to significantly debit an energy budget responsible for nestling development and growth. Nestling mortality and post fledging survivorship appeared linked to the impact of these energy demands.

Lesions associated with Philometroides huronensis (Nematoda: Philometridae) in the white sucker (Catostomus commersoni).

Lesions associated with Philometroides huronensis in the white sucker (Catostomus commersoni) of southern Ontario occurred during the spring (April-June) and were related to the development and release of first-stage larvae from the gravid nematode. With movement of the subgravid female into the membranous region of the fin, subepidermal tissues were mechanically disrupted and compacted near the nematode. Gravid females were encapsulated by fibrous tissue. Release of first-stage larvae from the gravid nematode was facilitated by a cutaneous opening, disruption of the fibrous capsule and rupture of the nematode. An acute local inflammatory response was associated with this function. Spent nematodes were sequestered and resorbed.

Schistosoma mansoni: identification of chemicals that attract or trap its snail vector, Biomphalaria glabrata.

A new bioassay for chemical attractants of aquatic snails demonstrated that Biomphalaria glabrata could be attracted to or trapped in the vicinity of homogenates of lettuce. Fractionation of homogenates revealed the amino acids glutamate and proline and the primary attractants. Attraction was specific for the L form of glutamate. Proline appeared to stimulate reproductive activity. Glutathione, gamma-aminobutyric acid, and a number of other compounds had no effect. Extracts of lyophilized snail tissue also attracted other snails and may thus contain pheromones. These results permit formulation and testing of controlled-release attractants designed to overcome the repellant effects of slow-release molluscicides, as well as the design of stimulants to be used with no-release poisons.