Effects of Water Immersion and Soil Moisture Content on Larval and Pupal Survival of Bactrocera minax (Diptera: Tephritidae)

Abstract

Bactrocera minax, one of the most devastating citrus pests in Asia, has two developmental stages (mature larva and pupa) that complete their life cycle in the soil. Currently, southern China has a climate with abundant autumn rains, and soil moisture can be a major factor affecting the survival of larvae and pupae of B. minax. In the present study, we evaluated the effects of water immersion and high soil moisture content on the development of mature larvae and pupae of B. minax. When immersed in water for 1 d, 100% of mature larvae of B. minax were knocked out. When larvae were immersed for less than 6 d, however, more than 92% of knocked-out larvae recovered within 24 h. The days of water immersion with 50% and 90% recovery ratios (indicated as RD50 and RD90) were 10.3 d and 6.4 d, respectively. When larvae were immersed less than 6 d, the mortality ratios of larvae were not significantly different from those that were not immersed at all. The days of immersion causing 50% and 90% mortality of larvae (MD50 and MD90, respectively) were 7.6 d and 11.1 d, respectively. The pupation ratios of larvae were also observed to be not significantly different compared to non-immersion, and the days of immersion causing 50% and 90% pupation (PD50 and PD90, respectively) were 6.6 d and 0.8 d, respectively. Larval respiration rates were reduced after water immersion as a strategy for larval survival. High water content was not detrimental to pupae of B. minax. Adult emergence did not significantly decrease in soil with high water content, even though pupae were under those conditions for 161–175 d. The respiration rates of pupae were lower in soil with different moisture levels and were not significantly different, which ensured the survival of pupae in high water content. Reduced respiration rate is a strategy for survival of larvae and pupae, and remarkable tolerance to high moisture conditions could explain the high rate of spread and geographical distribution of B. minax. The results of this study provide a reference for the occurrence and control of B. minax.

Arthropod Communities in Urban Agricultural Production Systems under Different Irrigation Sources in the Northern Region of Ghana

“…Such water sources often run through cities and carry a mixture of natural dilutes and human waste, laden with chemicals and pathogens. Irrigation water may also be a medium for the pupation of insect pests [ 9 ] and disease vectors, such as mosquitoes of the genus Anopheles and Culex [ 10 ]. As such, the usage of inadequately processed wastewater for irrigation that, in turn, can pose major threats to soil properties [ 11 ], as well as below and above-ground biodiversity [ 12 ], may negatively affect farmers’ and consumers’ livelihoods in West Africa.…”

An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination with waterlogging

“…Under exposure to severely hypoxic water, the pupae of semi-terrestrial caddisfly were most sensitive relative to aquatic larvae and terrestrial larvae ( Cavallaro and Hoback, 2014 ). Increasing the duration of the larval immersion of Bactrocera minax in water also led to the increased mortality ( Li et al, 2019 ). This study is the first report on the effects of the waterlogging approach on the genus Bradysia .…”

“…It was documented that short-term flooding has been shown to successfully control soil insect pests such as the cranberry girdler, Chrysoteuchia topiaria and wireworm, Agriotes obscurus , several grasshopper species, the root weevil Diaprepes abbreviates ( Martin et al, 2010 ) and citrus fly, Bactrocera minax ( Brust et al, 2007 ; Fitzpatrick, 2007 ; Li et al, 2019 ; van Herk and Vernon, 2006 ; Woodman, 2015 ). For instance, Diabrotica larvae are susceptible to flood-induced mortality ( Hoback et al, 2002 ).…”

Life cycle and eco-friendly management of Chinese fruit fly (Bactrocera minax) in sweet orange (Citrus sinesis Osbeck) in Nepal

“…The pupa overwinters in the soil at the depth of 3-7 cm (Wu et al, 2008), they can remain in the soil for 5 to 7 months (Van Schoubro, 1999). Because of the remarkable ability to lower their respiration rate, pupa of Chinese fruit fly can survive even in high moisture content (Li et al, 2019). The adult emerges from the soil in April/May; their number reached a peak in June/ July and starts to decline in august (Van Schoubro, 1999, Dori et al, 2006and Wu et al, 2008.…”