Abstract
Both prey type and abiotic conditions limit performance of phytoseiid predators. The exotic predatory mite, Typhlodromalus aripo developed and reproduced when maintained on eggs and active stages of the cassava green mite (CGM) Mononychellus progresivus at three different temperatures. At the highest temperature of 33 °C and the lowest at 12 °C, mite survival was less than 15 % over a period of ten days with low fecundity. At 12 °C, immatures took longer to reach maturity, while at 33 °C high mortality (>80 %) occurred. The best performance was recorded at 27 °C and 75 % relative humidity. Typhlodromalus aripo was also able to feed, develop and reproduce on the crawlers’ stage of the whitefly, Bemisia tabaci and the nymphal stage of the mealybug, Phenacoccus manihoti, though a low survival rate (<10 %) was observed for the stages of protonymph, deutonymph and adults. Normal life stage development and egg hatchability were recorded at 27 °C and 75 % RH. The egg stage exhibited high drought tolerance (70 % hatching at 40 % RH). Typhlodromalus aripo females consumed less than 3 crawlers and produced less than one egg/day when fed with B. tabaci and P. manihoti at 75 % RH. The study indicated that for successful utilization of T. aripo in the biological control of CGM, it would be important to introduce the predator at low prey density whether in absence or presence of alternative prey on cassava. In conclusion, results revealed T. aripo to have drought resilient survival attributes which enhances this phytoseiid as an effective biological control agent.
Highlights
The predatory mite, Typhlodromalus aripo De Leon (Acari: Phytoseiidae) was first described from Trinidad and reported later from Brazil (Denmark and Muma 1973)
The present study aims to evaluate T. aripo consumption rate, immature development and reproduction on different cassava pests as preferred and alternative prey types of cassava green mite (CGM), P. manihoti and B. tabaci in different temperatures and humidity conditions
Typhlodromalus aripo consumed significantly (P < 0.05) different quantities of the four prey types of CGM, B. tabaci and P. manihoti whatever the life stage considered and the temperature applied at 75 % RH (Table 1)
Summary
The predatory mite, Typhlodromalus aripo De Leon (Acari: Phytoseiidae) was first described from Trinidad and reported later from Brazil (Denmark and Muma 1973). This predator among others was introduced to East Africa during the 1990’s to control the cassava green mite (CGM), Mononychellus progresivus Doreste, a pest that constrains production of the cassava (Gutierrez 1987; Hanna et al 1998). In Kenya T. aripo was released in 1995/6 and http://www1.montpellier.inra.fr/CBGP/acarologia/ ISSN 0044-586-X (print). ISSN 2107-7207 (electronic) its establishment and subsequent persistence led to reduction of severity of CGM on cassava (Kariuki et al 2000; Jones 2002; Yaninek and Hanna 2003). The success of T. aripo in suppressing populations of CGM has been mainly attributed to the predator’s capacity to live in the apices of cassava during the dry spells and feeding on the plant sap and other alternative food substances in absence of CGM (Magalhães and Bakker, 2002; Gnanvossou et al 2003; Onzo et al 2003, 2009)
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