Oecophylla longinoda (Hymenoptera: Formicidae) Lead to Increased Cashew Kernel Size and Kernel Quality

Weaver ants, Oecophylla spp., are known to positively affect cashew, Anacardium occidentale L., raw nut yield, but their effects on the kernels have not been reported. We compared nut size and the proportion of marketable kernels between raw nuts collected from trees with and without ants. Raw nuts collected from trees with weaver ants were 2.9% larger than nuts from control trees (i.e., without weaver ants), leading to 14% higher proportion of marketable kernels. On trees with ants, the kernel: raw nut ratio from nuts damaged by formic acid was 4.8% lower compared with nondamaged nuts from the same trees. Weaver ants provided three benefits to cashew production by increasing yields, yielding larger nuts, and by producing greater proportions of marketable kernel mass.

Occurrence of sexuals of African weaver ant (Oecophylla longinoda Latreille) (Hymenoptera: Formicidae) under a bimodal rainfall pattern in eastern Tanzania

The African weaver ant, Oecophylla longinoda, is being utilized as a biocontrol agent and may also be targeted for future protein production. Rearing of mated queens in nurseries for colony production is needed to cater for such demands. Thus, newly mated queens must be collected for use as seed stocks in the nurseries. To collect mated queens efficiently it is important to identify when sexuals occur in mature colonies. We studied the occurrence of sexuals in O. longinoda colonies for 2 years in Tanga, Tanzania, a region characterized by a bimodal rainfall pattern. We found that O. longinoda sexuals occurred almost throughout the year with abundance peaks from January to April. Production of sexuals appeared to be triggered by rainfall, suggesting that populations in areas with long rainy periods may show prolonged mating periods compared to populations experiencing extended dry periods. The bimodal rain pattern may thus cause a low production over a long period. The average yearly production of queens per tree and per colony was estimated to be 449 and 2753, respectively. The average number of queens per nest was 17. Worker abundance declined from January to March with minimum by the end of this period, being inversely proportional to the production of sexuals. In conclusion, mated queens may be collected almost throughout the year, but most efficiently by the onset of the long rainy season when the majority disperse.

Organosulfates as tracers for secondary organic aerosol (SOA) formation from 2-methyl-3-buten-2-ol (MBO) in the atmosphere

2-Methyl-3-buten-2-ol (MBO) is an important biogenic volatile organic compound (BVOC) emitted by pine trees and a potential precursor of atmospheric secondary organic aerosol (SOA) in forested regions. In the present study, hydroxyl radical (OH)-initiated oxidation of MBO was examined in smog chambers under varied initial nitric oxide (NO) and aerosol acidity levels. Results indicate measurable SOA from MBO under low-NO conditions. Moreover, increasing aerosol acidity was found to enhance MBO SOA. Chemical characterization of laboratory-generated MBO SOA reveals that an organosulfate species (C(5)H(12)O(6)S, MW 200) formed and was substantially enhanced with elevated aerosol acidity. Ambient fine aerosol (PM(2.5)) samples collected from the BEARPEX campaign during 2007 and 2009, as well as from the BEACHON-RoMBAS campaign during 2011, were also analyzed. The MBO-derived organosulfate characterized from laboratory-generated aerosol was observed in PM(2.5) collected from these campaigns, demonstrating that it is a molecular tracer for MBO-initiated SOA in the atmosphere. Furthermore, mass concentrations of the MBO-derived organosulfate are well correlated with MBO mixing ratio, temperature, and acidity in the field campaigns. Importantly, this compound accounted for an average of 0.25% and as high as 1% of the total organic aerosol mass during BEARPEX 2009. An epoxide intermediate generated under low-NO conditions is tentatively proposed to produce MBO SOA.