Biological Control Agent Of Water Hyacinth Research Articles

Utilization of an Introduced Weed Biological Control Agent,Megamelus scutellaris(Hemiptera: Delphacidae), by a Native Parasitoid

Summary A native parasitoid, Kalopolynema ema (Schauff and Grissell) (Hymenoptera: Mymaridae), has begun utilizing a new host, Megamelus scutellaris Berg (Hemiptera: Delphacidae), the introduced biological control agent for waterhyacinth, Eichhornia crassipes (Mart.) Solms (Commelinales: Pontederiaceae). Parasitism rates varied between outdoor M. scutellaris rearing tanks and sentinel plants placed in the field, with parasitism rates in the tanks being higher.

Differences in Seasonal Variation between Two Biotypes ofMegamelus scutellaris(Hemiptera: Delphacidae), a Biological Control Agent forEichhornia crassipes(Pontederiaceae) in Florida

Summary Two biotypes (Paraguay and Argentine) of Megamelus scutellaris (Berg) (Hemiptera: Delphacidae), a biological control agent for waterhyacinth, were tested for differences in number of progeny, development time, and weight across average south Florida seasonal temperatures. Significant differences between the biotypes were found at summer temperatures. In general, progeny of the Paraguay biotype weighed more than those of the Argentine biotype during the summer.

Failure of Eccritotarsus catarinensis, a biological control agent of waterhyacinth, to persist on pickerelweed, a non-target host in South Africa, after forced establishment

Abstract Waterhyacinth (Eichhornia crassipes) is the most damaging aquatic weed in South Africa, where five arthropod biological control agents have been released to date. The most recent introduction, a South American mirid, Eccritotarsus catarinensis, was shown to utilize Pontederia cordata (pickerelweed) during laboratory host-specificity trials. This did not influence the decision to release the mirid in South Africa, where the exotic pickerelweed is a declared invader. However, in the United States of America where waterhyacinth is also a problem, the possibility of spillover damage on indigenous pickerelweed may preclude the release of the mirid. In this study, E. catarinensis did not establish on pickerelweed in the field in South Africa, following either confined releases, where the mirids were initially released into sleeve cages, or unconfined releases where mirid-infested pickerelweed plants were placed amongst pickerelweed stands. We thus recommend that E. catarinensis be considered as an additional control agent of waterhyacinth in North America.

Infectivity of Insect Pathogens against Neochetina eichhorniae, a Biological Control Agent of Waterhyacinth

Several insect pathogens were tested for infectivity against Neochetina eichhorniae Warner (Coleoptera:Curculionidae), a biological control agent for waterhyacinth, Eichhornia crassipes (Mart.) Solms. No mortality resulted from exposure to 21 strains of Bacillus thuringiensis. No significant mortality resulted from exposure to 2 strains of Metarhizium anisopliae. Although treatment of adult weevils with 6 strains of Beauvaria bassiana produced no significant mortality, 2 strains (BbAFA - 35%, Bb 5647 - 65%) did result in statistically significant mortality. Exposure to 2 strains of Steinernema carpocapsae resulted in 60-70% mortality. Our results indicate limited potential for these insect pathogens to control N. eichhorniae in resource recovery or wastewater treatment facilities.

Acigona infusella, 1 a Potential Biological Control Agent for Waterhyacinth: Observations in Argentina (with Descriptions of Two New Species of Apanteles1a by L. De Santis)2

Larvae of the pyralid moth, Acigona infusella (Walker) (Lepidoptera: Pyralidae), sporadically cause heavy damage to waterhyacinth, Eichhornia crassipes (Mart.) Solms, in Argentina, by tunneling in the petioles and crown. Larvae are heavily attacked by parasites and pathogens. In the field larvae attack only E. crassipes, E. azurea (Sw.) Kunth (anchored waterhyacinth), Pontederia cordata L. (pickerelweed), and P. rotundifolia L., all in the Pontederiaceae. At times, it is abundant on all these species. Handfed larvae also completed development and produced adults on sliced ears of corn and cut culms of rice, but they did not feed on any of the other 11 plant species tested. When larvae were placed on growing plants, 6 larvae survived 45 days on rice and 8 survived 13 days on corn, but none completed their development and pupated. In the laboratory females did not exhibit strong ovipositional specificity, and in the field they often oviposited on plant species taller than waterhyacinth. Acigona infusella has never been reported to feed on rice, corn, or any other beneficial plant in Argentina, even in areas where waterhyacinth grows nearby. Two new species of parasitoids of Acigona infusella, Apanteles fluitantis and Apanteles cordoi (Hymenoptera: Braconidae), are described by Luis De Santis.