Population dynamics and infestation of Holopothrips fulvus Morgan (Thysanoptera: Phlaeothripidae) in dwarf cashew genotypes.

The objective of this study was to evaluate the Holopothrips fulvus Morgan (Thysanoptera: Phlaeothripidae) population dynamics and to identify dwarf cashew genotypes less infested by the pest in 2015 and 2016, under field conditions. H. fulvus population evaluations were carried out by monthly observations in the plants and using a score scale varying from 0 to 4. H. fulvus infestation occurred from October to December, and in the cashew genotypes CAP 112/8, CAP 121/1, CAP 131/2, CAP 145/2, CAP 145/7, CAP 128/2, CAP 120/4, CAP 123/6, CAP 130/1, and CAP 157/2 was dependent on the flowering period of the crop in 2015. In 2016, there was dependence in all evaluated genotypes between H. fulvus infestation and the cashew flowering period. In 2015, no significant differences were observed between the evaluated genotypes regarding H. fulvus infestation. In 2016, genotypes CAP 105/5, CAP 143/7, CAP 150/3, CAP 155/2, CAP 158/8, CAP 161/7, CAP 163/8, CAP 31, CAP 71, CAP 92, CAP 113, CAP 120, CAP 155, CAP 165, CAP 106/1, CAP 111/2, CAP 127/3, CAP 157/2, and BRS 226 were less infested. H. fulvus occurs from October to December and we could identify the dwarf cashew genotypes less infested by the pest.

Risk assessment of the occurrence of aflatoxin and fungi in peanuts and cashew nuts

In the present study, the occurrence of fungi and aflatoxins (AFs) in peanut and cashew nut samples was investigated. Mycological analysis revealed the presence of fungi in 58.8% of samples, and assessment of AFs by chromatographic methods revealed that 52.9% were contaminated by AFs. AFB1 was the principal component in all AF-contaminated samples, with a mean level of 14.0, and 1.08 µg/kg in peanut and cashew nut, respectively. Eleven samples (32.4%) exceeded the total AF maximum level (4 µg/kg) and 8 samples (23.5%) exceeded the AFB1 (2 µg/kg) established by the European Commission. Our findings suggest that the incidence of AFs emphasizes the need for regular monitoring and a more stringent food safety system to control AFs at the lowest possible levels in peanuts and cashew nuts. The hypothetical dietary exposure suggests that the food products evaluated may significantly contribute to the overall human exposure

Global Potential Distribution of Bactrocera carambolae and the Risks for Fruit Production in Brazil.

The carambola fruit fly, Bactrocera carambolae, is a tephritid native to Asia that has invaded South America through small-scale trade of fruits from Indonesia. The economic losses associated with biological invasions of other fruit flies around the world and the polyphagous behaviour of B. carambolae have prompted much concern among government agencies and farmers with the potential spread of this pest. Here, ecological niche models were employed to identify suitable environments available to B. carambolae in a global scale and assess the extent of the fruit acreage that may be at risk of attack in Brazil. Overall, 30 MaxEnt models built with different combinations of environmental predictors and settings were evaluated for predicting the potential distribution of the carambola fruit fly. The best model was selected based on threshold-independent and threshold-dependent metrics. Climatically suitable areas were identified in tropical and subtropical regions of Central and South America, Sub-Saharan Africa, west and east coast of India and northern Australia. The suitability map of B. carambola was intersected against maps of fruit acreage in Brazil. The acreage under potential risk of attack varied widely among fruit species, which is expected because the production areas are concentrated in different regions of the country. The production of cashew is the one that is at higher risk, with almost 90% of its acreage within the suitable range of B. carambolae, followed by papaya (78%), tangerine (51%), guava (38%), lemon (30%), orange (29%), mango (24%) and avocado (20%). This study provides an important contribution to the knowledge of the ecology of B. carambolae, and the information generated here can be used by government agencies as a decision-making tool to prevent the carambola fruit fly spread across the world.

Modeling occupancy of hosts by mistletoe seeds after accounting for imperfect detectability.

The detection of an organism in a given site is widely used as a state variable in many metapopulation and epidemiological studies. However, failure to detect the species does not necessarily mean that it is absent. Assessing detectability is important for occupancy (presence-absence) surveys; and identifying the factors reducing detectability may help improve survey precision and efficiency. A method was used to estimate the occupancy status of host trees colonized by mistletoe seeds of Psittacanthus plagiophyllus as a function of host covariates: host size and presence of mistletoe infections on the same or on the nearest neighboring host (the cashew tree Anacardium occidentale). The technique also evaluated the effect of taking detectability into account for estimating host occupancy by mistletoe seeds. Individual host trees were surveyed for presence of mistletoe seeds with the aid of two or three observers to estimate detectability and occupancy. Detectability was, on average, 17% higher in focal-host trees with infected neighbors, while decreased about 23 to 50% from smallest to largest hosts. The presence of mistletoe plants in the sample tree had negligible effect on detectability. Failure to detect hosts as occupied decreased occupancy by 2.5% on average, with maximum of 10% for large and isolated hosts. The method presented in this study has potential for use with metapopulation studies of mistletoes, especially those focusing on the seed stage, but also as improvement of accuracy in occupancy models estimates often used for metapopulation dynamics of tree-dwelling plants in general.

Efficacy of the African weaver ant Oecophylla longinoda (Hymenoptera: Formicidae) in the control of Helopeltis spp. (Hemiptera: Miridae) and Pseudotheraptus wayi (Hemiptera: Coreidae) in cashew crop in Tanzania.

BACKGROUND: Cashew, Anacardium occidentale, is an economically important cash crop for more than 300 000 rural households in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects such as Helopeltis anacardii, H. schoutedeni and Pseudotheraptus wayi. The African weaver ant, Oecophylla longinoda, is an effective biocontrol agent of hemipteran pests in coconuts in Tanzania, but its efficacy in the control of Helopeltis spp. and P. wayi in Tanzanian cashew has not been investigated so far. The aim of this study was therefore to evaluate the efficacy of O. longinoda in the management of these insect pests in the cashew crop at different sites of the Coast region of Tanzania. RESULTS: Colonisation levels of O. longinoda, expressed as weaver ant trails, varied from 57.1 to 60.6% and from 58.3 to 67.5% in 2010 and 2011 respectively. The mean number of leaf nests per tree varied from five to eight nests in 2010 and from five to nine nests in 2011. There was a negative correlation between numbers of nests and pest damage. Oecophylla longinoda-colonised cashew trees had the lowest shoot damage by Helopeltis spp. of 4.8 and 7.5% in 2010 and 2011, respectively, as opposed to uncolonised cashew trees with 36 and 30% in 2010 and 2011 respectively. Similarly, nut damage by P. wayi was lowest in O. longinoda-colonised trees, with only 2.4 and 6.2% in 2010 and 2011 as opposed to uncolonised trees with 26 and 21%. CONCLUSION: Oecophylla longinoda is an effective biocontrol agent of the sap-sucking pests of cashew in the Coast region of Tanzania and should be considered as an important component of IPM.

Investigations on Oecophylla longinoda (Latreille) (Hymenoptera: Formicidae) as a biocontrol agent in the protection of cashew plantations.

BACKGROUND: Cashew (Anacardium occidentale L.) has become a very important non-traditional tree crop in Ghana. The crop is, however, attacked by sap-sucking insects, particularly the mosquito bug, Helopeltis schoutedeni Reuter, the leaf-footed bug, Pseudotheraptus devastans (Dist.), and the coreid bug, Anoplocnemis curvipes (F.), which feed on shoots, panicles and fruits. Their damage is characterised by withering of the latter. In Ghana, Oecophylla longinoda Latr. occurs in large numbers on cashew and other native plants, but little is known about its relationship with insect pests. The relationship between O. longinoda and shoot and panicle damage by sap-sucking bugs and the effectiveness of O. longinoda as a biocontrol agent in the protection of cashew as compared with two chemical insecticides, lambda-cyhalothrin (Karate) and cypermethrin + dimethoate (Cyperdim), were therefore investigated at Bole in the northern region of Ghana. RESULTS: There was a negative correlation between numbers of O. longinoda nests and pest damage. Trees treated with cypermethrin + dimethoate (969 mg AI mL(-1) tree(-1)) and lambda-cyhalothrin (100 mg AI mL(-1) tree(-1)) recorded the smallest bug numbers, followed by O. longinoda. Trees infested by Oecophylla longinoda and trees treated with cypermethrin + dimethoate and with lambda-cyhalothrin had less than 6% pest damage to shoots, panicles and fruits, while water-sprayed trees recorded damage as high as 36.8% (shoots) in February, 32.9% (panicles) in February and 37.8% (fruits) in March. Cypermethrin + dimethoate again recorded the highest (485.0 kg ha(-1)) nut yield, followed by O. longinoda (431.0 kg ha(-1)), with water recording the lowest (93.0 kg ha(-1)) nut yield. CONCLUSION: The results indicate that O. longinoda can be used to control some sucking bugs as effectively as some insecticides.