Amaranth is an African indigenous vegetable that is gaining popularity due to its nutritional, medicinal, and economic values. In East Africa, frequent outbreaks of Lepidopteran leaf-webbers, Spoladea recurvalis F. (Lepidoptera: Crambidae) and Udea ferrugalis Hübner (1976) are reported on this crop, causing up to 100% foliage loss. The larval endoparasitoid Apanteles hemara Nixon is also frequently found associated with these pests during the outbreaks, however, its performance on both pests has never been documented. Laboratory studies were therefore carried out to assess the acceptability and suitability of S. recurvalis and U. ferrugalis to A. hemara. Both leaf-webber species were accepted by and suitable for the parasitoid. The mean host searching time and oviposition attempts were neither affected by rearing host nor test host. The total developmental time of A. hemara ranged between 10.6 ± 0.16 and 12.8 ± 0.30 days on both hosts. The sex ratio of the parasitoid was female biased when reared on S. recurvalis but male biased on U. ferrugalis. When offered 50 larvae of leaf-webbers for 24 h, a single female A. hemara achieved parasitism rates from 42.63 ± 5.80 to 44.55 ± 5.95, while a cohort of five females resulted in parasitism rates between 87.25 ± 2.70 and 94.67 ± 1.98 %. There was no significant difference between hosts in regard to progeny fitness at each parasitoid density. The parasitoid also caused significant nonreproductive larval mortalities in the hosts. The implications of these findings for mass rearing of the parasitoid as well as for conservation and augmentative biological control of amaranth lepidopteran leaf-webbers in East Africa are discussed.
-Varroa -specific hygienic behavior is a hereditary trait of honey bee (Apis mellifera ), which supports resistance to Varroa destructor . This study investigated the response of Apis mellifera scutellata to Varroa -infested worker brood cells in Kenya, East Africa. Uncapping, removal of the brood, and disappearance of the introduced mite were recorded in a total of 690 cells into which live mites were introduced. We recorded a high proportion of untouched cells in controls (median, 80%) compared to manipulated cells in which mites had been introduced (median, 12.5%) with a significant difference (GLMM, p < 0.001). Mites were removed and cells were recapped in about 26% of the artificially infested brood cells. When ten, eight, and five mites were singly introduced in closely neighboring brood cells, hygienic bees were more responsive in the high mite density regime of eight and ten mites, an indication of a possibility that chemicals play a role in identification of Varroa -infested brood cells.Apis mellifera scutellata / artificially infested brood cells / Varroa -specific hygienic behavior
The development, survival and reproductive potential of diamondback moth Plutella xylostella (Linnaeus) were studied at 25^1 8C in the laboratory in response to two cultivated Brassica oleracea cultivars (cabbage B. oleracea var. capitata and kale B. oleracea var. acephala) and four wild crucifer species Erucastrum arabicum, Raphanus raphanistrum, Rorippa nudiuscula and Rorippa micrantha. Rorippa micrantha was the most preferred species in oviposition choice tests, while cabbage and kale were least preferred. First instar larval mining period differed significantly between plant species with the longest period recorded on cabbage (3.0 days) and the shortest on R. micrantha (0.4 days). Pupal weight was significantly lower for larvae reared on R. nudiuscula, while those of the others were similar. The developmental period from first instar to adult was the shortest on R. micrantha (14.1 days) and the longest on R. raphanistrum (15.6 days). Survival to adult was not statistically affected by the host plant species. Adult longevity ranged between 18.2 days on R. raphanistrum and 24.7 days on R. nudiuscula. The females were significantly heavier than the males on all plant species. However, males lived longer than females. Moths reared on R. nudiuscula recorded the highest fecundity (326 eggs), while moths reared on cabbage had the lowest fecundity (262 eggs). Kale and R. nudiuscula recorded the longest generation time of 31.7 days, while E. arabicum had the highest net reproductive rate (126.4 eggs per day). The highest intrinsic rate of increase was calculated for R. micrantha (0.179) and the lowest for kale (0.147). This study shows the suitability of wild crucifers as hosts for P. xylostella and indicates that they may play a major role as reservoir for the pest during the absence of cultivated host plants.
Seasonal incidences ofPlutella xylostella, diamondback moth (DBM) and its associated natural enemies were investigated in two agro-ecological zones of the major crucifer growing areas of Kenya in 2005 and 2006. DBM larvae and pupae were collected from the cabbage and kale crops grown in farmers' field and maintained in the laboratory for the emergence of parasitoid or DBM. Four larval, one larval-pupal and one pupal parasitoid species were recorded from DBM. The parasitoids recovered were Diadegma semiclausum, Diadegma mollipla, Itoplectis spp., Cotesia plutellae, Apanteles spp., Oomyzus sokolowskii and Brachymeria species. D. semiclausum was the most dominant species throughout with highest parasitism rates of over 70% recorded in the highlands. C. plutellae, Apanteles and Brachymeria were recovered from mid-altitude semi-arid areas. Generally, parasitism was significantly higher on Brassica oleracea var. capitata. D. semiclausum displaced the indigenous parasitoids from B. oleracea var. capitata.
Mango (Mangifera indica L.) is the third most important fruit crop in the tropics following citrus and banana. It is consumed as a fresh fruit and different forms of preparations for its multifaceted nutritional values. Mango production in Ethiopia is constrained by infestation of white mango scale (WMS), Aulacaspis tubercularis Newstead. White mango scale was recorded from Ethiopia for the first time in 2010, in a mango orchard in Loko in the western part of the country. This study was conducted from June 2013 to May 2014 to document the population dynamics of white mango scale in Western Ethiopia. Randomized Complete Block Design was used for the sampling in two mango orchards, Arjo and Bako. Scale population peaked in April at Arjo and in May at Bako showed marked decline with decreasing precipitation. Abundances of eggs, crawlers and sessile stages of the scale showed significant differences among most of the study months (P0.05). The abundance of sessile scales was significantly higher at Bako than at Arjo (P0.05). In both study areas, white mango scales were significantly more abundant on the upper leaf surfaces than the lower (P0.05). At Bako, male scale numbers were significantly higher than those of the females (P0.05). The study found that the decline and build-up of white mango scale populations are affected by rainfall, whereas the effects of other environmental factors on scale numbers need to be investigated.
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