Bioecology of the mango mealybug, Rastrococcus iceryoides green (Hemiptera : Pseudococcidae) and its associated natural enemies in Kenya and Tanzania

Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae), an alien invasive mealybug pest of Asian origin was first detected in Tanzania in 1989. This pest rapidly spread by the mid-1990s and was soon present in Coastal Kenya and Northern Malawi, where it has been regarded and remains a major pest of mango. Because of its novelty status, there was no information on its biology, ecology and its natural enemies that could aid development of management efforts. This study, therefore, was initiated to establish the bioecology of R. iceryoides and its natural enemies in Kenya and Tanzania, and to explore for efficient co-evolved natural enemies in the aboriginal home of the pest in India. Based on the exploratory survey data, two correlative approaches, Desktop-GARP (Genetic Algorithm for Rule-set Prediction) and Maxent ( Maximum entropy) were used to identify climatically suitable areas in Africa that are agro-meteorologically similar to the aboriginal home of the pest. The first step was to carry out a countrywide survey in Kenya and Tanzania to establish the distribution, host-plant relationship and natural enemies of this pest. The survey revealed that R. iceryoides infested twenty-nine plant species particularly Mangifera indica L. and Cajanus cajan (L.) Millspaugh, and the wild plants Parkinsonia aculeata L., Caesalpinia sepiaria Roxb, and Deinbollia borbonica Scheft. A total of six primary parasitoid species were recovered from R. iceryoides with Anagyrus pseudococci Girault (Hymenoptera: Encyrtidae) predominating. Thirty-eight species of predators belonging to 14 families were also recorded. Despite the presence of these indigenous natural enemies, their ability to regulate the population of R. iceryoides was inadequate. In laboratory host preference studies, M. indica, Cucurbita moschata Duchesne, P. aculeata and C. cajan were found to be the most preferred host plants in view of improving laboratory mass rearing of this pest and the parasitoid. The impact of O. longinoda on the biological control activities of A. pseudococci in the laboratory revealed that percentage parasitism of R. iceryoides by A. pseudococci was significantly higher on ant-excluded trials than on ant-attended trials. Worker ants were observed to remove mummified mealybugs, which resulted in significantly reduced percentage of adult parasitoid eclosion. Oecophylla longinoda showed aggressive behaviour and caused a significant mortality of A. pseudococci during the exposure period. The spatial and temporal population dynamics of this pest was also studied and revealed that populations of R. iceryoides followed an annual cycle which is synchronized with the mango fruiting season, with a peak incidence occurring during the dry season (December to February) on all plant parts. The population dynamics of R. iceryoides and its natural enemies were significantly and positively influenced by temperature, while it was significantly and negatively correlated with rainfall. The exploratory survey in India showed that R. iceryoides is widely distributed throughout the state of Tamil Nadu and infested ten cultivated and wild plant species with extremely low levels of infestation. Percentage parasitism based on the proportion of mummified R. iceryoides was high on all host plants. Out of eleven primary parasitoid species, Praleurocerus viridis Agarwal (Hymenoptera: Encyrtidae) and Anagyrus chryos Noyes&Hayat (Hymenoptera: Encyrtidae) were the most dominant and widely distributed species. In addition to the parasitoids, 10 predator species from 7 families were recorded. Based on the model established with data from India, it was determined that climatically suitable areas for introduction of promising parasitoids in Africa include the humid tropical coastlines of Kenya and Tanzania, as well as some restricted areas in West and Central Africa. Studies of the potential worldwide distribution of R. iceryoides showed that the pest might poses a serious threat on a worldwide scale as it could narrowly become established in all the mango producing countries in the continents.Thesis (PhD)--University of Pretoria, 2013.Zoology and Entomologyunrestricte

Host-plant relationships and natural enemies of the invasive mealybug, Rastrococcus iceryoides Green in Kenya and Tanzania

The invasive mango mealybug, Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) believed to be native to Southern Asia has rapidly invaded Kenya and Tanzania. A survey was carried out from February 2008–July 2009 to study its geographical distribution, host plant relationships and associated parasitoids in both countries. Our results infer that R. iceryoides is widely distributed across the coastal belts of both countries. Rastrococcus iceryoides was recorded from 29 cultivated and wild host plants from 16 families. Twenty-one of these host plants are new records. Among the cultivated host plants, M. indica (8153.6±19.2/20 twigs and 6054.3±29.2/80 leaves in Kibaha, and 2979.3±33.8/5 fruits in Kinondoni) and Cajanus cajan (L.) Millspaugh (1452.2±44.7/80 leaves and 4672.3±54.7/twig in Morogoro) recorded the highest levels of infestation. Parkinsonia aculeata (7892.3±25.1/20 twigs, 11.6±1.25/80 leaves and 42.2±5.1/5 fruits in Kinango), Caesalpinia sepiaria Roxb (266.3±6.3/80 leaves and 3116.1±17.5/20 twigs in Kinondoni) and Deinbollia borbonica Scheff., (215.7±10.3/80 leaves and 2253±22.9/20 twigs in Kibaha) were found to be the most heavily infested wild host plants. Six parasitoid species were recovered and are reported here for the first time to parasitize R. iceryoides. Anagyrus pseudococci Girault was the most dominant species accounting for 21% parasitism on M. indica and 20% parasitism on P. aculeata in Tanzania and Kenya, respectively. Despite this, the ability of the parasitoid to regulate the population of R. iceryoides was inadequate. Therefore, there is a need for foreign exploration and introduction of efficient coevolved natural enemies from its aboriginal home of Southern Asia to minimize its impact on horticulture in Africa.This work was supported by the European Union (SANTE 2007 147–790). The Hlabisa HIV Treatment and Care Programme has received support through the United States Agency for International Development (USAID) and the President’s Emergency Plan (PEPFAR) under the terms of Award No. 674-A-00-08-00001-00.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-04182017-11-30hb2017Zoology and Entomolog

Consumers’ perception towards eggs from laying hens fed commercial black soldier fly (Hermetia illucens) larvae meal-based feeds

This study evaluates consumer perceptions of eggs from hens that are fed black soldier fly (Hermetia illucens)/ BSFL-based diets, and the socioeconomic factors that influence consumer perceptions in Kenya. Findings demonstrate that increased awareness creation and evidence-based demonstration regarding the benefits of BSFL-based feed in poultry production would improve consumer perception and foster uptake of this rapidly growing and emerging technology. The survey was conducted through a random sample of 200 consumers responsible for their household or family purchases.Australian Centre for International Agricultural Research (ACIAR)Bill & Melinda Gates FoundationCurt Bergfors Foundation Food Planet Prize AwardNorwegian Agency for Development CooperationNetherlands Organization for Scientific Research, WOTRO Science for Global Development (NWO-WOTRO)Rockefeller FoundationCentre of Excellence in Sustainable Agriculture and Agribusiness Management (CESAAM) of Egerton University KenyaUnited Kingdom’s Foreign, Commonwealth and Development Office (FCDO)Swedish International Development Cooperation Agency (Sida)Swiss Agency for Development and Cooperation (SDC)Federal Democratic Republic of EthiopiaGovernment of the Republic of Keny

Farmers’ perceptions of commercial insect-based feed for sustainable livestock production in Kenya

This study evaluated farmer’s perceptions of commercial insect-based feed (IBF) products and assessed factors that would influence adoption. Findings show that over 90% of the farmers were willing to use IBF. The principal component analysis (PCA) identified feed performance; social acceptability of the use of insects in feed formulation; feed versatility and marketability of livestock products reared on IB as key attributes that would inform farmers’ purchase decisions. Public partnerships with resource-endowed farmers and farmer groups are recommended to improve knowledge sharing on IBF.Australian Centre for International Agricultural Research (ACIAR

Antimicrobial activity of chemically and biologically treated chitosan prepared from black soldier fly (Hermetia illucens) pupal shell waste

This study presents the first comparative analysis of chemical and biological extraction of chitin and chitosan from black soldier fly (BSF) pupal exuviae. The antibacterial activity of chitosan was also evaluated. Chemical and biological extraction gave a chitin yield of 10.18% and 11.85%, respectively. Biological extraction gives high yields as compared to chemical extraction and can be used as an alternative method since it is inexpensive and eco‐friendly. A maximum chitosan yield of 6.58% was achieved via chemical treatment. The findings demonstrate that chitosan from BSF pupal exuviae could become a novel therapeutic agent for drug development against resistant strains of bacteria.Bill & Melinda Gates FoundationCurt Bergfors Foundation Food Planet Prize AwardAustralian Centre for International Agricultural Research (ACIAR)Norwegian Agency for Development CooperationNetherlands Organization for Scientific ResearchWOTRO Science for Global Development (NWO–WOTRO)Rockefeller Foundatio

Improving Phosphate Rock Use Efficiency In Organic Farming

Between 45 to 81% of the total phosphorus (P) fertilizer applied to soils in sub-Saharan Africa is absorbed in the soil, which among other factors reduce crop yield and contributes to high poverty in the region.  The objective of the study was to assess the effect of different phosphorus rock (PR) management on carrot yields, P recovery and use efficiency.  Different volumes (100, 200, 300, 400, and 500 mLs) of organic (lemon and pineapple) juices and water were used to dissolve 100 g of PR. The available P concentration in the solution was determined using a standard protocol. The solution with the high P concentration as well as powdered PR was each composted with manure and crop residues. Thereafter, a field experiment was set up on Humic andosols and Orthic acrisols to compare the effect of the dissolved PR applied directly with compost, to dissolved PR composted,  powder PR composted, powdered PR applied directly with compost, Triple supper phosphate applied directly with compost, compost and the soil alone (as a control). Our findings showed that lemon juice could release over 65% of the available P from PR and the combined application of the dissolved PR and compost at planting increased P recovery and use efficiency, and carrot yields on both soils as compared to the other treatments

Ecological transition from natural forest to tea plantations : effecton the dynamics of malaria vectors in the highlands of Cameroon

From October 2002 to September 2003, an entomological survey was carried out in a rural forested fringed village in the highlands of Mount Cameroon region to determine the temporal dynamics of the anopheline population and the intensity of malaria transmission. A total of 2387 Anopheles spp. were collected, with A. funestus predominating (59.9%), followed by A. hancocki (24.4%) and A. gambiae s.l. (15.7%). Considerable differences were observed in the nocturnal biting cycles of parous mosquitoes, with peak activity in the latter part of the night. PCR revealed that all specimens of the A. funestus group were A. funestus s.s. and all specimens from the A. gambiae complex were A. gambiae s.s. of the S molecular form. Plasmodium falciparum sporozoite rates of 17.3% and 8.5% were recorded for A. funestus and A. hancocki, respectively, with an anthropophilic rate of 96.3%. A strong positive correlation (r = 0.996) was found between the human-biting rate and the entomological inoculation rate (EIR). Malaria transmission was very high and perennial, with an estimated annual EIR of 460.1 infective bites per person per year. These results confirm that in high agricultural activity areas, A. funestus can be by far the major malaria vector responsible for malaria transmission

Beneficial sterols in selected edible insects and their associated antibacterial activities

Abstract Edible insects are increasingly gaining popularity as research reveals multiple benefits. However, the rediscovery of natural products from insects as medicinal agents has received limited attention. This study aimed at evaluating the diversity of sterols in extracts of nine edible insects and potential antibacterial activities. Dichloromethane extracts of these insects were analyzed using gas chromatography–mass spectrometry to identify important sterols, followed by evaluation of their anti-bacterial activities. Nineteen sterols were identified with the highest recorded in African fruit beetle [Pachnoda sinuata (47.37%)], crickets [Gryllus bimaculatus (36.84%) and Scapsipedus icipe (31.58%)]. Cholesterol was the most prevalent, except in black soldier fly (Hermetia illucens). Bioactivity revealed S. icipe as the most potent extract against Escherichia coli and Bacillus subtilis whereas G. bimaculatus was highest against Methicillin-susceptible Staphylococcus aureus 25923. These findings unravels the diversity of sterols in edible insects and their possible application in food, pharmaceutical and cosmetic industries

Effect of six host plant species on the life history and population growth parameters of Rastrococcus iceryoides (Hemiptera : Pseudococcidae)

The effect of 6 host plant species [Mangifera indica L., Cajanus cajan (L.) Millspaugh, Coffea arabica L., Cucurbita moschata Duchesne, Parkinsonia aculeata L., and Ficus benjamina Roxb.], on bionomics of the mango mealybug Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) was studied in the screenhouse. Biological and life table parameters of the mealybug differed significantly among the host plants. Developmental period (egg to adult) was shortest on M. indica (23.5 days and 25.3 days for females and males, respectively), whereas it was longest on F. benjamina (33.0 days and 37.3 days for females and males, respectively). The egg to adult female survivorship was highest on C. moschata (79.6%) and lowest on C. arabica (30.9%). Fecundity was highest on C. moschata (811.3 egg/female) followed by M. indica (716.8 egg/female). The sex ratio was female-biased on C. moschata, M. indica, C. cajan and P. aculeata. Adult mealybug longevity also varied with host plant for both mated and unmated females. Adult female body length and width were significantly higher on C. moschata, M. indica, C. cajan and P. aculeata than on F. benjamina and C. arabica. The highest intrinsic rate of natural increase (rm), finite rate of increase (λ) and the shortest mean generation time (GT) and doubling time (Td) were recorded on M. indica. The highest and lowest net reproductive rate (Ro) occurred on C. moschata and C. arabica, respectively. The implication of these findings in relation to damage, population growth and management of R. iceryoides on the target crops is discussed.German Federal Ministry for Economic Cooperation and Development (BMZ) to the icipe-African Fruit Fly Programme (AFFP) and a student fellowship to the senior author by the German Academic Exchange Service (DAAD).http://journals.fcla.edu/flaenthb2013ab201