Effect of different photoperiods on the growth, infectivity and colonization of Trinidadian strains of Paecilomyces fumosoroseus on the greenhouse whitefly, Trialeurodes vaporariorum, using a glass slide bioassay

Growth, infectivity and colonization rates for blastospores and conidia of Trinidadian strains T, T10, and T11 of Paecilomyces fumosoroseus (Wize) Brown and Smith were assessed for activity against late fourth-instar nymphs of Trialeurodes vaporariorum (Westwood) (Homoptera:Aleyrodidae) under two different photoperiods (24 and 16 hour photophase). A glass-slide bioassay and a fungal development index, modified for both blastospores and conidia, were used to compare the development rates of the fungal strains on the insect hosts. Fewer adult whiteflies emerged from nymphs treated with blastospores and reared under a 16:8 hour light:dark photoperiod than a 24:0 hour photoperiod. Eclosion times of whitefly adults that emerged from nymphs treated with the different strains of conidia were similar over the 8 day experimental period at both light regimes. The percent eclosion of adult whiteflies seems to be directly correlated with the speed of infection of the blastospore or conidial treatment and the photoperiod regime. The longer photophase had a significant positive effect on development index for blastospores; however, a lesser effect was observed for the conidia at either light regime. Blastospore strain T11 offered the most potential of the three Trinidadian strains against T. vaporariorum fourth-instar nymphs, especially under constant light. The glass-slide bioassay was successfully used to compare both blastospores and conidia of P. fumosoroseus. It can be used to determine the pathogenicity and the efficacy of various fungal preparations against aleyrodid pests.

Screwworm eradication program in Central America

The Screwworm Eradication Program has been extremely successful in its efforts to achieve its goal of eradication of screwworms through Central America and establishement of a permanent biological barrier in the eastern half of Panama. Following eradication of screwworms from Mexico in 1991, eradication was achieved in Belize in 1992, in Guatemala in 1993, and in El Salvador in 1994. Honduras has been free of screwworms since Janaury 1995, and the number of cases in Nicaragua has dropped, as of April 1995, to about 4 percent of the average number of cases found during the period June-August 1993. (AU)

A study of the use and impact of pesticides in Saint Lucia

The use of chemical for pest vector control has lead to the reduction in the incidence of several communicable diseases and improvement in food quality and production. Nevertheless, the toxic properties of these pesticides present a separate threat to human health and the health of the environment. The potential for occupational exposure is of particular concern in the Caribbean where agriculture and vector control programs employ more than 40 percent of the labour force. Within Saint Lucia alone, 1,500,000 kilograms of pesticides (insecticides, fungicides and herbicides) were imported in 1990. A multi-phasic project was developed to assess and reduce the incidence of acute pesticide poisoning and the prevalence of chronic pesticide poisoning in Saint Lucia and in Trinidad and Tobago. Collaborators in this intersectoral undertaking include the Ministries of Agriculture/Health in Saint Lucia and in Trinidad and Tobago, Caribbean Environmental Health Institute (CEHI), and Caribbean Epidemiology Centre (CAREC). This paper will summarize the results of the first phase of the project: a survey of the knowledge, attitudes, practices and beliefs (KAPB) of vector control officers in Saint Lucia and members of the Saint Lucia Banana Growers Association (SLBGA)(AU)

Routine focal mollusciciding after chemotherapy to control Schistosoma mansoni in Cul de Sac valley, St. Lucia

Concluding results of a ten year schistosomiasis control programme in Cul de Sac valley, St. Lucia, are described. After an area wide mollusciciding campaign (1970-1975), and a surveillance/treatment programme supplemented with selective population chemotherapy in 1975 and 1976, prevelence rates of Schistosoma mansoni were reduced to low levels. To prevent a resurgence of transmission a cost effective routine focal mollusciciding programme, suitable for public health implementation was evaluated from 1977 to 1981. Streams and main collector drains in banana fields, considered to be potential S. mansoni transmission sites, were treated every four weeks with Bayluscide 6076 emulsifiable concentrate (Clonitralide). Snail populations were effectively controlled in the treated areas but large numbers were present where no treatment was given. Only 0.06 percent of sentinel snails became infected. Prevalence of infection in the human population remained low (over-all 5 percent) and intensity of infection at a level not normally associated with schistosomal disease. Since control started ten years earlier the level of potential contamination has fallen by 92 percent in high transmisssion areas. The four year programme cost US$12,909, of which 54 percent was for molluscicide, 27 percent for labour and 19 percent for transport, equipment and sundries. The average annual cost per head of population was US$0.46

Reduction in transmission of Schistosoma mansoni by a four-year focal mollusciciding programme against Biomphalaria glabrata in St. Lucia

The effect on transmission of Schistosoma mansoni of a focal snail control programme was investigatsd over four years amongst approximately 1250 people living in 5 communities in the steep-sided Soufriere river valley, St. Lucia, West Indies. Bayer 6076 was applied from constant flow drip cans to 12 stream sections at a target dose of 8mg/litre clonitralide every four weeks. Only proven and potential transmission sites were treated (AU)

Schistosoma mansoni control in Cul de Sac Valley Saint Lucia. II Chemotherapy as a supplement to a focal mollusciciding programme

After an intensive area-wide mollusciciding campaign, over four and a half years, transmission of Schistosoma mansoni was reduced. A cheaper scheme suitable for the follow-up or consolidation stage of control was evaluated and two selective population chemotherapy campaigns using hycanthone (2 mg/kg b.w.) and oxamniquine (15mg/kg b.w.) were mounted. Prevalence dropped to 6 percent and 3 percent in areas with previously high and low levels of transmission respectively. Calculations suggested that these figures were falsely low and that perhaps 20 percent of the population were still excreting S. mansoni ova in small numbers. The unco-operative groups in the population are probably more important in maintaining a reservoir of infection in the community than persons with light infections undetected by the sedimentation concentration stool examination technique used. The benefit of more sensitive but more costly examination techniques is not clear since the importance of very light infections in transmission is uncertain. Case detection absorbs an increasing proportion of the total cost of chemotherapy programmes with fewer cases being found amongst the same number screened. Using hycanthone (649 treated) the cost per person protected was $0.74 and using oxamniquine (264 treated) $0.94. The need to develop low cost consolidation or follow-up procedures for preventing a resurgence of transmission after successful control, when the infection is no longer of public health importance, is stressed. (AU)

Schistosoma mansoni control in Cul de Sac Valley, Saint Lucia. 1. A two-year focal surveillance-mollusciciding programme for the control of Biomphalaria glabrata

An area-wide mollusciciding campaign in Cul de Sac valley, St. Lucia reduced incidence of Schistosoma mansoni from 22 percent to 4.3 percent between 1970 and 1975. Following this, a two-year focal surveillance-mollusciciding programme was introduced. Sites of potential transmission of S. mansoni were identified and routinely searched for Biomphalaria glabrata. If found, the site was treated with clonitrralide 25 percent emulsifiable concentrate. Two chemotherapy campaigns supplemented the snail control programme. As a result of the combined measures, incidence of the infection dropped from 4.3 percent to 1.0 percent and from 2.2 percent to 0.6 percent in areas originally of high and low transmission respectively. The cost of protecting the 7,000 population was US $20,362: of these costs, labour absorbed 68 percent, transport 24 percent, equipment 4 percent and molluscicide 4 percent. The cost per person per year protected was US $1.45 which compares favourably with the $3.24 of the previous scheme. Although effective and relatively cheap, this programme was still dependent on a high standard of supervision for maximum benefit. (AU)

Some aspects of food hygiene in the parish of St. Michael, Barbados

From the findings of the survey it was revealed that the majority of businesses were owner operated. Both the owners and employees indicated in the majority of cases that they had had no training for their jobs nor any lectures in food hygiene, although they all thought such lectures should be given. However, in reply to such questions as "What are the food bourne diseases", "What health criteria should a worker have to satisfy, before being allowed to work in the handling of food", "How important are flies to the foodhandler and what precautions can be taken against them?", the majority of the respondents were able to give satisfactory answers although a much lower percentage did not know. (AU)

Preliminary parasitological results of a pilot mollusciciding campaign to control transmission of Schistosoma mansoni in St. Lucia

A mollusciciding campaign was begun in Cul-de-Sac Valley, St. Lucia, at the end of 1970, following several years of epidemiological studies in which transmission of Schistosoma mansoni was found to be high in settlements on the valley floor but low in hillside settlements. Postcontrol (1971-73) findings in children, when compared with precontrol data and with data from an adjacent valley having a similar transmission pattern, show significant reductions in prevalence, incidence, and intensity of infection.(AU)

Bionomics and chemical control of free-tailed house bats (Molossus) in Trinidad

Since the construction of buildings by man, house bats infesting roof spaces have presented a serious nuisance, constituting health and economic problems throughout the world, especially where there is no proper bat-proofing in the initial construction. In Trinidad this problem is acute. Previous studies on control measures are evaluated. Experiments carried out used locally available chlorinated hydrocarbon insecticides. Results indicate that where a repellent was required, B.H.C. was preferred and where a toxicant was more desirable, D.D.T. Either of these insecticides resulted in the removal of house bats from roof spaces in 3-4 weeks and D.D.T. had a residual effectiveness of at least one year. Methods of insecticide application and assessment of bat populations are discussed, also biological data are given on the 2 species of Molossus involved. These studies vear directly on the problem as found in the Southern United States and Puerto Rico, or wherever other species of house bats are involved (AU)