False codling moth (FCM), Thaumatotibia leucotreta is a key pest of citrus orange and other plants causing fruit loss through larval feeding. Although this pest is native to sub-Saharan Africa little is known on its performance on orange and vegetables in Kenya and Tanzania. Our objective was to assess the incidence, oviposition preference and offspring performance of FCM on orange and vegetables, namely, okra, African eggplant, chili and sweet peppers. A higher percentage of orange with FCM damage symptoms was recorded from the ground than from the tree sampled fruit. However, FCM larval incidence was higher for the latter (tree sampled fruit). The highest FCM larval incidence amongst the vegetables was recorded on African eggplant (12%) while the lowest was on okra (3%). Orange was the most while African eggplant was the least preferred for oviposition by FCM. Among the vegetables tested, strong oviposition preference was found for sweet pepper; however, larval survival was lowest (62%) on this crop. Highest larval survival (77%) was recorded on orange. Most demographic parameters (i.e., intrinsic rate of increase, doubling time) were comparable among the studied host plants. The results are discussed in line of FCM management.

The polyphagous moth, Thaumatotibia leucotreta (Meyrick) is among the major constraints to the horticultural industry in East Africa. In a search of sustainable control methods, the pathogenicity of the dry conidia of 17 Metarhizium anisopliae (Metschn.) and five Beauveria bassiana (Bals.) (Vuill.) isolates were tested against T. leucotreta moths. The conidial uptake by a single moth, horizontal transmission, and effect of fungal inoculant on egg-laying and hatchability for the pest were also assessed. The findings from this study showed that tested fungi were virulent to the moths, with 12 isolates causing mortality that ranged between 58.8 and 94.2% for M. anisopliae and three isolates between 57.6 and 84.6% for B. bassiana. The entomopathogenic fungi isolates, M. anisopliae ICIPE 69 and B. bassiana ICIPE 279 were highly virulent with low lethal times to 50% mortality (LT50) of 3.81 and 5.13 d, respectively. The isolate, ICIPE 69 conidia acquisition by a single moth were approximately 4.58 × 106 and 3.51 × 106 for males and females, respectively. The lowest survival rate (3.33 %) caused by inoculum transmission was recorded in donor males compared to 16.67% in recipient males. Fecundity was reduced by 33.6 and 25.9% for donor and recipient females, respectively. The pest can acquire conidia from the treated substrate and transmission is then possible between adults. ICIPE 69 is virulent and reduces the reproduction potential of the pest after transmission. The findings are discussed in the prospects of microbial control of this pest using an autodissemination technique.

Introduction. Host preference of Zeugodacus cucurbitae in three vegetables was determined under choice and no-choice experiments. Materials and methods. The experiments were conducted in both semi-natural (under cage) and natural (no cage) field conditions. The trials were run for three seasons between March 2013 and July 2014 in Morogoro Region, Tanzania. In each season, two sets of plots of watermelon Citrullus lanatus, cucumber Cucumis sativus and pumpkin Cucurbita sp., were established in mono and mixed cropping systems. A set of plots was placed under individual cages and another set of plots was left open. Colonies of Z. cucurbitae were regularly established from wild cucurbits and the emerging adults were maintained on artificial diets. The adults were released into cages once in a cropping season, at a sex ratio ratio of 1:1. A total of 60 and 180 adults were released into choice (4×4 m) and no choice (4 × 12 m) plots respectively. Open fields were infested naturally. Released adults were between 21 and 30 days old post emergence. Flies were released between six and eight weeks after sowing the vegetables. Fruits were harvested a week after release of flies into cages. Trials were also conducted to determine the dominant cucurbit infester in cucumber. Infestation rates and incidences were determined and used to indicate preference of Z. cucurbitae among the three vegetables. Results and discussion. Highest infestation rate of Z. cucurbitae was recorded in watermelon while lowest in pumpkin. Infestation rates were significantly high in fruits grown under no choice compared to choice plots. More flies emerged from fruits grown in no choice plots. However, infestation rates were not significantly different among fruits from natural and semi-natural conditions. Other cucurbit infesters, Dacus bivittatus, D. frontalis, D. vertebratus and D. ciliatus emerged from fruits grown in open (no cage) field plots. Further results show that Z. cucurbitae dominated Dacus bivittatus and D. frontalis in cucumber. Conclusion. Watermelon is the most preferred host of the dominant cucurbit infester Z. cucurbitae.