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Papaya mealybug (PMB), Paracoccus marginatus , native to Mexico and Central America, invaded Kenya in 2016 causing severe yield losses of between 57% and 91% and £2224/ha household economic losses annually. A classical biological program for PMB involved the importation of Acerophagus papayae , a koinobiont endoparasitoid, from Ghana into the quarantine facility at Kenya Agricultural and Livestock Research Organization, Muguga. Laboratory bioassays were conducted to evaluate the suitability of A. papaya e to parasitize PMB. Parasitism rates, sex ratio and development time of the parasitoid were evaluated under choice and no-choice experimental conditions. High parasitism rates of 72.5 ± 5.9 and 75.0 ± 3.8% were recorded in third instar and adult female PMB, respectively, and lower parasitism rates of 43.8 ± 4.6 % were recorded in second instars, under no-choice test conditions. Significant differences in host choice were noted when A. papayae was offered several host stages, with third instars being preferred over second instars. Adult females were preferred over third instars. Adult parasitoids were released and monitored for their establishment at six papaya farms in the Coastal region of Kenya from December 2021 to November 2022. Parasitoid establishment was recovered within the first month of release. Parasitism levels varied across the sites with the highest parasitism of 72.89 % recorded in Kwale. Findings from this study highlight the potential of A. papayae as a good candidate for biological control of PMB in Kenya and Africa beyond. [Display omitted] • Acerophagus papayae parasitized all the papaya mealybug instar stages evaluated under lab conditions. • Older papaya mealybug instars produced many females Acerophagus papayae than males. • Field-released A. papayae established at all the six research sites of the coastal region of Kenya. [ABSTRACT FROM AUTHOR]

Liriomyza leafminers represent important threats to the horticulture sector in East Africa. Parasitism rates of local parasitoids are reported to be low and the endoparasitoid, Chrysocharis flacilla (Walker) (Hymenoptera: Eulophidae), was introduced in Kenya for a classical biological control program. Acceptability and suitability bioassays were conducted on the three economically important Liriomyza species in Africa (Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), Liriomyza sativae (Blanchard) (Diptera: Agromyzidae), and Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). Foraging behavior, developmental time, sex ratio, parasitism rates, host pupal mortality, and body indices of C. flacilla were assessed. Results showed that the three Liriomyza leafminer species were accepted and suitable to C. flacilla. Foraging time was significantly shorter on L. trifolii than on L. sativae and L. huidobrensis. Ninety-eight per cent of females successfully oviposited in the three-host species. Female parasitoids were significantly aggressive in attempting to oviposit on L. huidobrensis than on L. sativae and L. trifolii. High parasitism rates ranging between 73 and 78% were observed from the three Liriomyza hosts, but no significant difference among hosts. C. flacilla-induced significant nonreproductive pupal mortality ranging from 23 to 35%, an attribute rare among endoparasitoids. In all three Liriomyza hosts, the parasitoid progeny was female biased. Parasitoid development period ranged between 16 and 24 d. Female parasitoids reared on L. huidobrensis were significantly bigger than those reared on L. sativae and L. trifolii.The acceptance to local Liriomyza leafminers and high host suppression ability is potential for considerations of C. flacilla in the management of Liriomyza spp. in Africa. [ABSTRACT FROM AUTHOR]

Dolichogenidea gelechiidivoris (Marsh) (Syn. Apanteles gelechiidivoris) (Hymenoptera: Braconidae), a konoibiont larval endoparasitoid of the South American tomato pinworm Tuta absoluta (Meyrick), was imported into Kenya in 2017 for the first classical biological control of T. absoluta in Africa. We determined the thermal thresholds of D. gelechiidivoris , with T. absoluta as host, using life cycle simulation modelling. Life-table data of D. gelechiidivoris were generated at six constant temperatures (10, 15, 20, 25, 30, and 35 °C, 65 ± 5% RH, and 12L: 12D photoperiod). Multiple non-linear functions were fitted to model some aspects of the biology of the parasitoid, including its longevity, mortality, reproduction, and senescence using Insect Life Cycle Modelling (ILCYM) software. The phenology models established were used to estimate life table parameters. Except at 35 °C, D. gelechiidivoris completed its development (i.e., egg-larval-pupa-adult) at all tested temperatures. The minimum temperature threshold from egg to cocoon was 7.0 °C and 5.9 °C from cocoon to adult wasp, while the maximum temperature thresholds were 34 °C and 36 °C, respectively. The optimal temperature for immature survival was 20–25 °C, while fecundity was optimum at 22.5 °C, with 69.5 eggs per female. Simulations of the population growth parameters indicated that the intrinsic rate of increase (rm) was maximum at 20 °C with 15 daughters per female per generation. Based on our findings the release of D. gelechiidivoris for inoculative augmentation in countries with temperatures ranging between 15 and 30 °C could be considered to control the pest. • Temperature effects on Dolichogenidea gelechiidivoris were studied using life cycle simulation modelling. • The parasitoid completed its development between 10 and 30 °C. • Its intrinsic rate of increase (rm) was maximum at 20 °C. • Regions with temperatures of 15–30 °C could be considered suitable for the releases. [ABSTRACT FROM AUTHOR]

Abstract: The biological performance of the exotic solitary endoparasitoid Phaedrotoma scabriventris (Nixon) (Hymenoptera: Braconidae) was studied on three important Liriomyza hosts (Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii), found in the vegetable production system of Kenya. All Liriomyza species tested were successfully parasitized by P. scabriventris. But, L. huidobrensis was the most preferred host with 92.2% of the females tested ovipositing in L. huidobrensis vs. 58.9% in L. sativae and 60% in L. trifolii. Within 24h of oviposition, P. scabriventris laid 1.5times more eggs in L. huidobrensis than L. sativae and L. trifolii and the average parasitoids emergence was 1.5times higher in L. huidobrensis compared to L. trifolii and L. sativae. There was no difference in the developmental period of P. scabriventris reared on the three Liriomyza species, however, the parasitoid mortality was 11.6times higher in L. sativae and L. trifolii compared to L. huidobrensis. Adult parasitoids reared on L. huidobrensis, were 1.3times bigger than P. scabriventris reared on L. sativae and L. trifolii, indicating that host size affect parasitoid development and survival. But, our findings suggested that host quality will not be a limiting factor for the development and establishment of P. scabriventris in the vegetable production system of Kenya. [Copyright &y& Elsevier]

Classical biological control-the introduction of exotic species to permanently control pests-offers an applied framework to test ecological and evolutionary hypotheses derived from invasion biology. One such hypothesis is that intraspecific hybridization can facilitate invasions because hybrids express higher phenotypic mean and/or variance than their parents. We tested this hypothesis using the parasitoid wasp Psyttalia lounsburyi, a candidate biocontrol agent for the olive fly Bactrocera oleae. Under laboratory conditions, we found marked differentiations between two populations of wasps, from South Africa and Kenya, in terms of life history strategies. South African females were better reproducers than Kenyan females, but the opposite was observed for males. Reaction norms showed different effects of developmental temperature on fecundity depending on the genotype. However, neither heterosis nor hybrid breakdown were observed. Hence, in this system, sex-specific effects of hybridization and genotype-by-environment interactions jeopardize any straightforward prediction on the fitness of hybrids. Therefore, our paper contributes to tone down the hybrid advantage hypothesis in invasion biology. [ABSTRACT FROM AUTHOR]