Maconellicoccus hirsutus (pink hibiscus mealybug) Management and Control September 2010 Contents 1.0 Introduction……………………………………………………………Page 1 2.0 Monitoring……………………………………………...…...…………Page 1 3.0 Preventative Measures...………………………………………………Page 2 4.0 Chemical Control……………………………………………………...Page 4 5.0 Physical Control……………………………………………………….Page 4 6.0 Biological Control……………………………………………….…… Page 4 7.0 Integrated Management……………………………….………………Page 6 8.0 References………………………………………………………………Page 6 1. Introduction Maconellicoccus hirsutus is a polyphagous insect pest which feeds on a wide range of important species including but not restricted to; coffee, guava, citrus, grape, peanuts, rose, beans, coconuts, maize, sugar cane, soursop, soybean, cotton, and other fiber crops (Ranjan, 2006; Ujjan & Shahzad, 2007; Reddy et al., 2009). The feeding of M. hirsutus causes malformation of shoots and leaves believed to be caused by the injection of a toxic saliva (Kairo et al., 2000). In addition to lowering the aesthetics of the plant, this deformation can also result in lowered crop yields and in heavy infestations, plant mortality (Kairo et al., 2000; Chong et al. 2008). Like other sap sucking insects, M. hirsutus also excretes a sugary honeydew on which sooty mold develops, further deteriorating the quality of the agricultural or forest product (Gonzalez-Gaona et al., 2010). The presence of large quantities of wax, characteristic of M. hirsutus infestations, also reduces the aesthetic and commercial value of ornamentals (Kairo et al., 2000). The overall annual cost of control and damages to the US economy from M. hirsutus is estimated to be around US$ 700 million, with the global estimate being around US$ 5 billion (Ranjan, 2006). 2. Monitoring Previously, the monitoring methods for Maconellicoccus hirsutus in new locations involved visual inspections and the analysis of samples from potential host plants, followed by the taxonomic determination of collected individuals (Gonzalez- Gaona et al., 2010). However, this process only can be used to detect infestations which are already present (Gonzalez-Gaona et al., 2010). Furthermore, Vitullo et al. (2009) looked at feeding symptoms of different Hibiscus cultivars and found that not all cultivars exhibit signs indicating the presence of M. hirsutus, implying that feeding symptoms are not a reliable indicator of infestation. Another method described by Serrano et al. (2001; Gonzalez-Gaona et al., 2010) involves the use of captive virgin female individuals in a trap as an attractant for male individuals. This method is impractical because of the difficulty of obtaining this type of female, their short life span, the risk of accidentally increasing pest populations and because it is not applicable in pest free areas bordering on the infested zones (Gonzalez-Gaona et al., 2010). IUCN SSC Invasive Species Specialist Group Page 1 Gonzalez-Gaona et al. (2010) demonstrated that a female sex pheromone developed by Zhang et al. (2004; in Gonzalez-Gaona et al., 2010) and composed of a mixture of lavandulyl and maconellyl in a 1:5 ratio significantly attracted males of M. hirsutus into traps and was also very specific. With the use of this pheromone in traps it was also possible to map the distribution of this species on a regional scale (Gonzalez-Gaona et al., 2010). In their experiment within plantations, red delta Biolure® traps containing a sticky substance on the interior base were installed with at least 20 m between them. 1 µg of the pheromone was placed in a grey rubber septum and placed inside the traps which were hung from the trees at a height of 1.5 to 3.0 m. For regional geographic distribution mapping, the traps were hung from trees at the edges of the highways and were between 4 and 6 km away from each other (Gonzalez-Gaona et al., 2010). Delta traps created from Tetrapack® waxed cardboard (from milk cartons) with an adhesive (such as Stickem®) applied to the bottom edge can also be utilised effectively with the pheromone placed inside (Gonzalez-Gaona et al., 2010). The effectiveness of three commercially available traps were compared by Francis et al., (2007) and Vitullo et al., (2007). Francis et al., (2007) found that Delta traps and double sided sticky cards caught more adult males than Jackson traps, while the Delta and Jackson traps were more effective at minimizing the capture of non- target insects. Conversely, Vitullo et al., (2007) found that Jackson traps caught as many or more males per square centimeter of trapping surface as those with larger surfaces (including the Delta traps), and the time required to count males in Jackson traps was significantly less than in green Delta, Pherocon IIB, and Pherocon V traps (Vitullo et al.,2007). Jackson traps also had the advantage of requiring only the sticky liners to be replaced as opposed to the other traps which must be replaced entirely or inspected in the field and then redeployed (Vitullo et al., 2007). These differing results perhaps could be attributed to the different timings and localities of the field trials with both taking place in Florida but with Francis et al., (2007) conducting theirs in April / May, 2005 in horticulture research plots while Vitullo et al., (2007) conducted theirs in September / October, 2005 in residential areas, parks and golf courses in addition to horticulture research plots. Fewer males were caught in the traps as the age of the lure increased, with significantly fewer caught in traps that had been pre-aged for 2 months (Francis et al., 2007). 3. Preventative Measures Following the introduction of M. hirsutus from Grenada to Trinidad in 1994, quarantine systems were strengthened and upgraded in all the neighbouring countries to prevent or delay introduction (Sagarra & Peterkin, 1999). Legislation was enacted in several countries. For example, in Trinidad and Tobago, M. hirsutus was proclaimed to be a "Notifiable Pest" in October 1995. This was followed by the revision of the plant protection regulations and the increased surveillance at ports of entry. Regional plant protection officers were trained in Trinidad to identify mealybug species and a regional public awareness campaign for the West Indies was conducted to increase public knowledge and to consequently decrease illegal trading and contraband by exporters, importers and passengers (Sagarra & Peterkin, 1999). The impact of these measures was limited, as M. hirsutus went on to spread to over 25 islands between 1994 and 2001 (Kairo et al., 2000). IUCN SSC Invasive Species Specialist Group Page 2 The prophylactic or pre-emptive release of the generalist biological control agent Cryptolaemus montrouzieri was used on Barbados and Dominica in an attempt to prevent the spread of M. hirsutus (Kairo et al., 2000). However there has been no evidence that such releases have been successful, with M. hirsutus eventually invading both islands (Kairo et al., 2000). Two hour laboratory fumigation of M. hirsutus using 48 mg/liter of methyl bromide was found to result in 100 % mortality of all life stages and has been suggested to provide quarantine security for infested commodities for export or import (Zettler et al., 2002). Methyl bromide, though, may adversely affect the quality of the treated crop and as a result should be used selectively on certain crops (Ranjan, 2006). It is also an ozone-depleting substance planned to be phased out by the Montreal Protocol (United Nations Environment Programme, 1992; in Follett, 2004) and as demand for it has subsequently gone down, prices have risen, creating a need for alternative methods of quarantine security (Follett, 2004). The irradiation of M. hirsutus for the phytosanitation of agricultural commodities was investigated by Jacobsen & Hara (2003). Tolerance of M. hirsutus to irradiation was observed to increase with maturity with eggs, crawlers and nymphs sufficiently controlled by doses of 100 Gy and over but with adults still capable of producing viable progeny at 100 Gy (Jacobsen & Hara, 2003). At 250 Gy, complete sterility was achieved in 13824 eggs oviposited by 3093 adults (Jacobsen & Hara, 2003). It is therefore suggested by Jacobson & Hara (2003) that the minimum effective dose for quarantine security is between 100 and 250 Gy. Follett (2004) investigated the use of heat vapour treatments to kill populations of M. hirsutus on agricultural commodities. On Chinese pea (Pisum sativum), treatments at 47 ºC required 45 min to kill all life stages whereas treatment at 49 ºC required only 10 min to kill all life stages with adults and nymphs being most tolerant to treatment at 47 ºC and the eggs being the most tolerant at 49 ºC (Follett, 2004). It is important to note that heat vapour treatment temperatures and times may vary across different hosts and that depending on the host, M. hirsutus may be able to remain protected and hidden, for example underneath the calyx in fruits like lime and persimmon (Follett, 2004). The susceptibility of different M. hirsutus life stages when immersed into hot water was studied by Hara & Jacobsen (2005) for the development of a postharvest disinfestation treatment. Different life stages were immersed in water at 47, 48, and 49 ºC in 2 minute and 4 minute increments. The results suggest that all life stages of M. hirsutus should be controlled by the 20-min 49 ºC hot water immersion treatment approved for control of fruit flies in longan and lychee, with the immature crawler stage being most susceptible and the egg stage being the most tolerant to hot water immersion (Hara & Jacobsen, 2005). 4. Chemical Control IUCN SSC Invasive Species Specialist Group Page 3 In India, granular insecticides have been shown to be ineffective while systemic insecticides are only used in heavy infestations (Mani, 1989; in EPPO, 2005). Additionally, inorganic oil emulsion sprays gave good control of M. hirsutus on guava (EPPO, 2005). However, in general, the use of pesticides is ineffective against M. hirsutus, partly because of its habit of hiding in crevices (EPPO, 2005) and because pesticides cannot penetrate the heavy layers of wax that shield the body (Kairo et al., 2000).