Mermithidae Research Articles

Release of Romanomermis culicivorax for the control of Anopheles albimanus in El Salvador II. Application of the nematode.

The mosquito breeding area of Lake Apastepeque, El Salvador, was treated 11 times over a 7-week period with Romanomermis culicivorax to control Anopheles albimanus and An. p. pseudopunctipennis. Parasitism averaged 58% but varied greatly from treatment to treatment and from site to site. However, three applications made during evening hours to avoid wind and wave action on the lake produced an average 86% parasitism. No significant differences in susceptibility to R. culicivorax were found between instars or between species. Also, no correlation was found between nematode dosage rates and levels of parasitism. Though the parasitism averaged about 60% of the desired level, Anopheles populations dropped from more than 10 per dip at the beginning of the release program to 0.6 per dip at the end of the release period (a 94% reduction). This is the first successful attempt to control mosquitoes on a large scale by using a parasite or pathogen.

Development of Resistance by the Southern House Mosquito to the Parasitic Nematode Romanomermis culicivorax

The mosquito Culex pipiens quinquefasciatus Say was found to have developed resistance to the mermithid nematode Romanomermis culicivorax Ross and Smith after some 300 generations. Parasitism was 32–42% higher in a native strain than in the laboratory strain of the host under similar conditions. Differences were even greater when the number of successful penetrations (multiple parasitism) was measured. No evidence of humoral defense mechanisms were found, and the mode of resistance has not been determined.

Romanomermis culicivorax: Morphological evidence of transcuticular uptake

The body surface of the parasitic stages of Romanomermis culicivorax (Mermithidae: Nematoda) is composed of three membranes overlying a layer of hypodermal cells. In all three membranes, there are pores ranging from 70–110 Å in diameter. The pores are large enough for the passage of ferritin particles and thus would allow passage of all nutrients required for growth. The gradient for this passage is probably established by the underlying hypodermal cells, whose microvilli also take up ferritin particles. These morphological features indicate a possible transport system for the uptake of nutrients by R. culicivorax. It is probable that other mermithid nematodes have similar systems.

Susceptibility of the Mosquito Nematode Romanomermis culicivorax (Mermithidae) to Pesticides and Growth Regulators 1

Pesticide susceptibility tests against preparasitic (infective stage) Romanomermis culicivorax Ross and Smith (= Reesimermis nielseni Tsai and Grundmann, auct., partim.) indicated that 24-h exposure to abate (0.001 ppm), malathion (0.100 ppm), baytex (0.003 ppm), dursban (0.001 ppm), Dimilin® (0.005 ppm), and Altosid® (0.005 ppm) produced no apparent detrimental effects to the viability and infectivity of R. culicivorax preparasites, or to the viability of the resulting postparasites. However, concn of 0.0035 and 0.004 ppm baytex, and 0.004 ppm dursban resulted in significantly lower preparasite infectivity when compared to controls, even though acute mortality of preparasites was not evident at these concentrations.

Virus-like particles in the nematode Romanomermis culicivorax (Mermithidae).

EARLY reports of virus infections of nematodes remain unconfirmed1,2, although more recently virus-like particles were reported occurring in the intestinal cells of a plant-parasitic nematode3. The only confirmed reports of viruses found inside nematodes are plant viruses which occur in the digestive tracts of their nematode vectors4. We report here the presence of virus-like particles in cells of the infective stages of the mosquito parasitic nematode, Romanomermis culicivorax.

Evidence of four molts in the Mermithidae

Evidence of four molts in the Mermithidae

Some observations on sex in the Mermithidae

Some observations on sex in the Mermithidae